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SYNTHESIS AND CHARACTERISATION OF TRANSITION AND INNER-TRANSITION METAL COMPLEXES USING BIOLOGICALLY ACTIVE TRIAZOLE INTRODUCTION The compounds containing thione (>C=S) and thiol (>C-SH) groups occupy prominant role in organic reagents. They possess , . . applications many m . , 41-43 industry , analytical48 50 chemistry. study, ie. . m „. . 44-47 medicine and in The compounds used in the present 3-substituted-4-amino-5-mercapto-l,2,4-triazoles belong to the above class of organic compounds. In recent years, a number of transition metal complexes of heterocyclic thiones have been studied are capable of undergoing thiol-thione 51-53 . Such ligands (-N=C-SH -NH-C=S) tautomerism and can act as mono as well as polydentate ligands. The Chemistry of 1,2,4-triazoles have been reviewed by Kroger et al 54 Triazoles have a wide range of applications. , reported to . . ,55 anti-viral , possess anti-tumor and analgesic activities. used as literature analytical reveals reagents that a 57 lot . of . , 56 anti-inflammatory , The An triazoles exhaustive work has tridentate Schiff bases with are survey also of been done on the complexes of 1,2,4-triazole with various metals The They are 58-66 heterocyclic amines containing ONS sequence have been tried for complexation with transition metals such as 32 copper(II), nickel(II), cobalt(II), zinc(II) and cadmium(II). The copper(II) shows bivalent tridentate behaviour and forms dimeric complexes. This has been substantiated by sub normal magnetic moments and electronic have synthesised eobalt(II), copper(II) . 67 spectra Garg et and nickel(II) have al nickel(II) , complexes of 5-mercapto-l,2,4-triazoles and they assigned complexes. 68 distorted octahedral geometry Recently, Gadag and Gajendragad and copper(II) 69 for these have prepared the complexes with 3-methyl and 3-ethyl derivatives of 4-amino-5-mercapto-l,2,4-triazole and they have assigned the high spin octahedral type configuration as shown below. H2Q H20 M = Ni(II), Co(II) Literature also records the complexing ability of 3-aryloxy-4-aryl-5-mercapto-l,2,4-triazoles with bivalent metal 33 ions 70 . In this case, X-ray studies reveal that the complexes possess cubic structure. The fungi toxicity of the complexes and the free ligands has been evaluated against H. Oryzae. Pannu et nickel(II), complexes al 71 , have reported manganese(II), cobalt(II), copper(II), of zinc(II), cadmium(II) 4n-Butyl-4H-l,2,4-triazole in and mercury(II) which the ligand shows bidentate behaviour in all the complexes except those of cadmium(II) and mercury(II). Recently, Garag et cobalt (II), al nickel(II) 72 , have reported tne complexes of and hydrazino-1,2,4-triazole copper (II) hydrochloride and with have 4-amino-3assigned the high spin distorted octahedral geometry for all the complexes on the basis of magnetic and spectral data. H2N H2° H2 n-n -N„ N= X 3—N-N^'^N w H2 I N Nv H20 M Recently, cobalt(II), bases nh2 physico-chemical nickel(II) have :N Co (II), Ni(II) and Cu(II) and have been reported coworkers 74 H in copper(II) the synthesised 34 studies chromium(III), complexes literature and of 73 . with Schiff Hiremath and characterised the metal complexes of aromatic heterocyclic Schiff bases on the basis of analytical and spectral data. Mxshra et nickel (II), al 75 , have copper(II) and 3- amino-5-(a/b)pyridylrecords 76 the reported the zinc(II) complexes 1,2,4-triazoles. complexes of some cobalt(II), Literature bivalent metal ions with also with 4- salicylaldiamino-3-mercapto- 5-phenyl-1,2,4 - triazole. Chromium(III), iron(III) and ruthenium(III) complexes of 3-methyl-4-benzylidineimino-5-mercapto-1,2,4-triazole have been reported m complexes the have literature been 77 . These characterised by bivalent magnetic metal and ion spectral studies and were assigned the low spin octahedral geometries. Kaushik et al 78 , have used triazoles as ligands for the complexation of bivalent metal ions. on the data. basis of analytical, Transition metal(II) These were characterised magnetic, thermal and spectral complexes of triazole derivatives have been synthesized by Satpathy and coworkers 79-82 and they have assigned octahedral geometry around the metal ions chosen, except cobalt(II) proposed. for which a tetrahedral geometry was The ligand as well as the complexes were tested for their toxicity against two fungi such as Fusarium oxysporium and Helminthosporium Oryzae by Horsfall method. 35 The copper(II) complex exhibited more fungi toxicity. Electrochemical with al 83 triazole . properties derivatives Literature 84 of have Ruthenium(III) been studied by complexes Fennena et also records the X-ray studies of zinc(II) chloride complexes with 4-amino-3,5-dimethyl-1,2,4- triazole. Vos et of al 85 , have studied the photo physical properties Ruthenium(III) 1,2,4-triazole complexes ligands. Reaction triazole with palladium(II) and co-workers containing of 3 -(Pyrazine-2-yl) 3,5-diamino-1,2,4 - compounds has been studied by Grap 86 Coordination compounds of 4-amino-1,2,4-triazole with metal chelates, bromates and nitrates have been appeared in the literature have 87 been Rhenium(V) studied cobalt (II), 88 complexes with triazole derivatives Mishra rhodium(III), et al nickel (II), 89 have zinc(II) studied the and cadmium(II) complexes with 4-amino-3-mercapto-l,2,4-triazole. Ruthenium(II) been reported and complexes their of Bis-(Pyridyl)triazoles absorption spectra, luminescence properties and electro chemical behaviour have been studied Copper(II) complexes 1,2,4-triazole-5-thione have , . 91 literature 36 of have 90 4 -amino-1,4-dihydro-3-methylbeen documented in the Ginzburg complexes been of et al the have by ESR copper(II) have Verma of copper (II) and they et al 93 , have have The complexes were characterised by the cobalt(II), with the 4-amino-3-hydrazino-5- magnetic and spectral data. studied complexes spectra. complexes mercapto-1,2,4-triazole. analytical, synthesised 3-amino-5-carboxy-1,2,4-triazole characterised reported , Revankar and Mahale nickel(II) and 94 copper(II) 3-methylsulfhydryl-4-amino-5-mercapto-1,2,4 - triazole and they have assigned octahedral configuration on the basis of magnetic and spectral data. They have also been evaluated for their antibacterial and antifungal activities. Patil and coworkers complexes triazole. with 95 synthesised the transition metal 3-substituted-4-salcylidene-5-mercapto-1,2,4 - The copper(II) complexes of these ligands are stable and show no reduction from copper (II) Zaydoun iron(II), et al cobalt(II), 96 , have nickel(II) to copper (I) . reported the manganese(II) , and copper(II) complexes with 1,2,4-triazole and they have characterised the complexes on the basis of analytical, magnetic and spectral data. Recently Mustafa Kamil Said et al iron(III) complexes triazole and they with 97 , have reported the 4-amino-3-mercapto-5-phenyl-1,2,4 - have assigned the high spin octahedral type 37 configuration. their The complexes antibacterial, have antifungal and Antitumour activity of iron(III) lympocytic leukemia test also been evaluated antitumour for activities. complex was tested with P388 system in the mice. P388 cells were maintained in RPMI-1640 medium supplemented with 5% fetal calf serum and kanamycin (100 ng/ml). Sinha nickel(II) and and coworkers 98 copper (II) have reported complexes dimercapto-5-phenyl-1,2,4-triazole with and octahedral geometry for cobalt(II), the they cobalt(II), 4-amino~3,5- have nickel(II) assigned and copper(II) complexes on the basis magnetic and spectral data. Very recently nickel(II), Yadawe and cobalt(II), Patil 99 copper(II), have studied the oxovanadium(IV), dioxouranium(VI), zirconium(IV), thorium(IV) and lanthanum(III) complexes of Schiff bases derived from 3-substituted-4-amino5-mercapto-l,2,4-triazole thiophene-2-aldehyde. characterised on the with All basis glyoxal/biacetyl/benzil/ the of complexes analytical, have spectral been and thermogravimetric data and they have also been evaluated for their antibacterial, antifungal and antiinflammetry activities. 3-substituted-4-amino-5-mercapto-l,2,4-triazoles synthesised and characterised by Hosur et al^^ 38 were They studied the antibacterial, antifungal, anticonvulsant activities. antiinflammetry and Results showed that their compounds were much potent towards herbicidal activities. Literature survey revealed that there is no report on the synthesis and characterisation of metal complexes using the compounds prepared by Hosur et al. importance of the above compounds, synthesise them. and Hence, synthesis, characterise the the present characterisation and investigation characterisation of also Schiff metal ions. bases 4-amino-5-mercapto-l,2,4-triazole biological it is worth to complexes biological deals the we thought, investigation ligands with transition metal present Keeping formed deals studies with of the above In addition to this, with formed with the preparation from the and 3 -substituted- salicylaldehyde their transition and inner-transition metal complexes. 39 from and EXPERIMENTAL SYNTHESIS OF LIGANDS The following ligands are used in the present investigation. 1. 3-N-methylmorpholino-4-amino-5-mercapto-l;2,4-triazole (MMAMT) 2. 3-N-methylpiperidino-4-amino-5-mercapto-l, 2,4-triazole (MPAMT) N \l-CH2 N SH 3. 3-N-methylmorpholino-4- salicylideneatrtino-5-mercapto-1,2,4triazole (MMSMT) 40 4. 3-N-methylpiperidino-4-salicylideneamino-5-mercapto-l,2,4triazole (MPSMT) 1. Synthesis of MMAMT It involves the following stages. i) Preparation of ethyl-morpholino-N-acetate To the ice cold solution of morpholine (0.4 mol) in dry benzene (200 ml), ethyl chloro acetate (0.2 mol) was added with vigorous shaking. The resultant steam bath for 8-10 hrs. washed with dry mixture was refluxed on a The resulting solid was filtered and benzene. The filtrate reduced pressure to remove dry benzene. was distilled under The ethyl morpholinoe N-acetate collected in the flask (B.P. 88-89 C) was used in the next stage. ii) Preparation Ethyl hydrate of morpholino-N-acethydrazide morpholino-N-acetate (0.1 mol) under mol) and were taken in absolute alcohol refluxed on a steam bath for 10-12 removed (0.1 reduced pressure. 41 hrs. The Excess hydrazine (50 ml) and solvent was resulting viscous hydrazide was cooled and kept under vacuum overnight to get in solid form. The solid hydrazide obtained was recrystallised in alcohol to get colourless needles. iii) Preparation of potassium-3 -(N-acetyl-morpholino) dithio- carbazinate Morpholino-N-acetahydrazide (0.1 mol), (0.15 mol) absolute and potassium hydroxide alcohol 12-14 hrs. voluminous (200 ml) and (0.15 carbon disulphide mol) were stirred continously It was then treated with dry ether potassium dithiocarbazinate. taken for about \200 ml) This was in to get filtered, washed with dry ether for several times and finally dried under vaccum. The potassium salt thus formed was employed for the preparation of triazole without further purification. iv) Preparation of 3-N-methylmorpholino-4-amino-5-mercapto- 1,2,4-triazole Hydrazine hydrate (0.2 potassium-3 -(N-acetylmorpholino) suspended in water hrs. ml) was acidified in white by solid and refluxed with adding form. water and further dried. 42 added dithiocarbazinate The resulting homogenous mixture was carefully MMAMT (10 ml) acetic This was acid to the (0.1 mol) stirring for 2 cooled in ice and drop filtered, wise to get washed with Finally it was recrystallised from alcohol. M.P. 187-188 C. 2. Synthesis of MPAMT Synthesis of MPAMT is similar to that of MMAMT. However instead of MPAMT morpholine used in MMAMT, piperidine was used in 100 3. Synthesis of MMSMT MMAMT (0.1 mol) in absolute alcohol and salicyaldehyde (100 ml) (0.1 mol) were taken containing two drops of Cone. HCl and refluxed on water bath for 4-5 hrs. The MMSMT separated after the evaporation of recrystallised from the alcohol was alcohol. M.P. 204-205°C. 4. Synthesis of MPSMT MPAMT (0.1-mol) in absolute alcohol and salicyaldehyde (100 ml) alcohol. M.P. 193-194 C. 43 were taken containing two drops of Cone. HCl and refluxed on water bath for 4-5 hrs. after the evaporation of (0.1 mol) The MPSMT separated the alcohol was recrystallised from SYNTHESIS OF COMPLEXES a) Synthesis of cobalt (II), nickel(II) and copper(II) complexes with MMAMT, MPAMT, MMSMT and MPSMT Metal(II) appropriate ligand chloride (0.01 (0.01 mol) mol) was treated with an in 1:1 ratio in alcoholic medium and refluxed for about one hr. 2g of sodium acetate was added to the reaction mixture and further continued refluxation for a period of washed 3 with hrs. The alcohol complex thus and finelly separated was dried in filtered, vaccum over fused calcium chloride. b) Synthesis of lanthanide(III) complexes with MPSMT Lanthanide(III) MPSMT (0.004 mol) for about 4 hours. nitrate (0.002 mol) was treated with in 1:2 ratio in absolute alcohol and refluxed Alcoholic ammonia was added to the reaction mixture to raise the pH to 6.5 and further refluxed for 2 hrs. The complex alcohol and thus separated finally dreid chloride. 44 was in filtered, vaccum washed over fused with dry- calcium RESULTS AND DISCUSSION All the cobalt(II), of the under yellow to taken dark nickel(II) ligands green in are and copper(II) brown, colour yellowish respectively. complexes green and They are insoluble in common organic solvents such as ethanol, methanol, benzene, chloroform etc, however solvents like DMF and DMSO. they are soluble The analytical, in polar molar conductance and magnetic moment data are given in Table I. Analytical data reveals lanthanide(III) that metal:ligand ratio is 1:1. The complexes of MPSMT are pale yellow in colour. They are soluble in DMF and DMSO. The analytical and molar conductance data are given in Table II. Analytical data reveals that metal:ligand ratio is 1:2. Molar conductivity measurements The copper (II) molar conductivity of cobalt(II), complexes measured in DMF at range 2.15 to 9.78 ohm -1 2 cm mol -1 10 -3 nickel(II) M. fall and in the . These values are much less than expected for 1:1 electrolytes1^1. Hence all complexes are treated as non-electrolytes. In lanthanide(III) complexes molar conductance values lie between 19.20-25.30 ohm -1 cm indicating that all the complexes are non-electrolytes. 45 2 mol -1 Table I Analytical, magnetic and conductivity data of Co(II) Ni(II) and Cu(II) complexes with MAMT, MPAMT, MMSMT and MPSHT Complex Compound ELEMENTAL ANALYSIS % Molar conductance Magnetic XM -1 code C C [Co(WAMT)Cl.(H 0) ] <• 24.46 H N 3.62 S 20.28 Cl M 9.18 10.25 ohm 16.94 2 cm moment -1 mol (B.M) 2.54 4.30 7.74 3.10 2.17 1.32 8.76 4.27 6.41 2.93 9.78 0.86 2 (24.38)(3.48)(20.33 (9.28)(10.39)(17.12) C [Ni(mAMT)Cl.(H^0)2] 24.70 3.84 20.42 9.25 10.64 17.24 (24.42)(3.48)(20.34)(9.39)(10.36)(17.05) C [Cu(MMAMT)Cl.H20] 25.46 3.42 20.42 9.60 10.55 19.12 (25.36)(3.65)(21.19)(9.66)(10.72)09.30) C [Co(MPAMT)Cl.(H20)2] 28.12 3.90 27.98 9.38 10.24 17.16 (28.09)(4.08)(28.02)(9.34)(10.36)(17.22) C [Ni(MPAMT)Cl.(H20)2] 28.36 4.18 20.82 9.30 9.78 18.02 (28.07)(4.09)(20.46)(9.40)(10.37)(18.12) C [Cu(MPAMT)C1.H20] 28.92 4.12 20.65 9.65 10.56 20.24 6 (29.19)(4.00)(21.27)(9.72)(10.79)(19.46) C [Co(MMSMT)(H20)2] 40.57 4.58 13.75 7.75 — 14.25 (40.55)(4.65)(13.55)(7.73) C [Ni(MMSMT)(H 0) ] 8 40.62 4.59 13.54 7.65 (14.14) — - 14.25 2.77 22 (42.14)(3.85)(16.37)(9.35) C 4.90 [Cu(hWSMT)] 43.58 3.88 14.50 8.15 (20.52) — 16.55 1.50 9 (43.92)(3.95)(14.65)(8.44) C [Co(MPSMT)(H^0)2] 40.45 4.64 13.75 7.85 (16.63) — (40.78)(4.53)(13.53)(7.76) C [Ni(MPSMT)(H20)2] 40.75 4.60 13.76 7.84 [Cu(MPSMT)] 44.00 4.05 14.50 8.35 14.35 — 14.10 The results given in parenthesis are theoretical values 46 2.65 (14.21) — 16.15 12 (44.22)(3.98)(14.75)(8.46) 4.92 (15.67) (40.82)(4.32)(13.65)(7.77) C ' (16.64) 1.55 Table II Analytical, Conductance and Magnetic data of lanthanide (111! nitrate complexes with ligand MPSMT Complex Elemental. Analysis Complex code C: H N (%) £ M Molar conductance ^•M ohm 1 cm 2 B! [La(MPSMT)^NO ] H 0 3 2 42 . 96 4 . 32 (43 . id (4 . 55! 18 . 57 16 . 3 8 7 . 48 (18..42! (7 . 66) (16 . 64) 22 . 2 B2 [Ce(MPSMT)zN0 3,H2° 4 1 . 82 4 . 72 (42 . 15) (4 . 44 ) 17 ..86 7 . 66 16 . 15 (18 ,.03) (7 . 49) (16 . 39) 20 . 4 B3 [Pr(MPSMT)2N0 312H2° 41 ..48 4 .. 82 (41 . 23 ) (4 . 84) 17 ..78 7 . 43 16 . 74 (17 ..64) (7 . 33) (16 . 15) 21 . 6 B [Nd(MPSMT)2N0 3)2H2° 4 ..73 40 ..95 (40 ..26) (4 ..69) (17 ..27) (7 . 15) (16 . 10 ) 40 ..22 4 .,30 (40 ,. 00) (4 . 66! 17 ..30 6 . 92 (17 .11) (7 . id 3 9 .. 99 4 .. 58 (39 . 91! (4 .. 65! (17 .07} (7 ..09) (16 .85! [Sm(MPSMT)2N0 313H2° B B6 [Eu(MPSMT)2N0 313H2° 17 ,. 55 16 . 84 7 . 24 6 . 85 16 . 68 16 .68 21 . 5 25 ,. 3 (16 .66! 16 - 75 20 .. 7 B7 [Gd(MPSMT)2N03 12H2° 40 . 36 4 .. 65 (40 .49) (4 . 72 ) 17 .55 7 ..23 (17 .32) (7 .19) 17 .28 (17 . 66 ) 19 . 2 B8 [Tb(MPSMT)2N03 ] 2H20 40 . 27 4 . 65 (40 . 40 ) (4 .71) 17 . 18 7 ..00 (17 .28) (7 .18) 17 . 66 (17 . 84 ) 20 .. 1 B9 [Dy(MPSMT)2NC>3 ]2H20 40 .12 4 . 42 (40 . 23 ) (4 .69) 17 .46 7 .26 (17 . 27 ) (7 . 32) 18 .65 22 . 9 (18 . 16) 40 . 74 4 .42 (40 . 04 ) (4 . 67) 17 .27 7 .. 32 (17 .13) (7 .11) (18 . 57) 40 .22 4 . 55 (39 . 77} (4 . 63) 17 .48 6 . 98 <17 .03) (7 . 07) (19 .11) 43 .46 4 .86 (43 . 84) (5 .id 18 .48 7 .34 (18 .75) (7 .79) 10 .75 (10 .84) B10 B11 B12 [Er(MPSMT)2N03 )2H20 [Yb(MPSMT)2N03 ] 2H20 [Y(MPSMT)2N031 2H 0 The results given in parenthesis are theoritical values 47 18 . 86 19 .35 22 . 5 24 .. 9 24 . 7 , -1 mo 1 Magnetic moment measurements Cobalt(II) complexes Cobalt(II), form a d paramagnetic tetrahedral or 7 ion, having two unpaired electons can complexes six having coordinated either four octahedral coordinated geometry. The magnetic susceptibility which decides a particular geometry is controlled by many factors like strength of and degree of the spin orbit coupling. the ligand field Cobalt (II) complexes in tetrahedral geometry show magnetic moment in the- range 4.2-4.7 B.M. However in octahedral geometry the values fall in the and C 14 are range 4.7-5.2 B.M. The u __ values of eff cobalt (II) complexes C 4.30 and 4.27 B.M. respectively, which are much below the range expected for octahedral cobalt(II) magnetic values polymeric suggests form. The complexes are 4.90 are in good that magnetic the with that These subnormal complexes moment and 4.92 B.M. agreement complexes. values may of respectively. of complexes exist C7 and in C These values of octahedral geometry. Nickel(II) complexes Q Nickel(II), form paramagnetic a d ion, having two unpaired electrons can complexes 48 having either four coordinated tetrahedral or six coordinated octahedral geometry. The magnetic susceptibility which decides a particular geometry is controlled by many factors like strength of the ligand field and degree of the spin orbit coupling. Nickel(II) complexes in tetrahedral geometry show magnetic moment in the range 3.6 to 4.1 B.M., where as in octahedral geometry a value of 2.9 to 3.3 B.M. is observed. In the present nickel (II) investigations complexes C , 2 C , 5 C 8 the magnetic moments and C 11 of lie in the range 2.93 to 3.15 B.M. expected for octahedral geometry around nickel(II) ion. Copper(II) complexes The assignments of geometry around copper (II) magnetic property is not straight forward. magnetic moment at room temperature, ion from On the basis copper(II) compounds of 9 (d ) can be classified into two main groups. 1) Majority of these compounds show normal magnetic moments corresponding to one unpaired electron Sometimes higher values upto 2.20 to orbital streochemical contribution. significance, 49 B.M. These but they (1.73 B.M.). are observed due values do have no indicate the absence of any appreciable spin-pairing between the unpaired electrons of the metal atoms. 2) Some of the copper(II) compounds, display magnetic moment values lower than the spin-only value unpaired electron tricoordinated Example, copper(II) (1.73 B.M.) copper(II) carboxylates complexes. These magnetic moments are due to some kind of between copper centres, either of a for one and subnormal spin interaction direct nature or of super-exchange type. The fall in These magnetic the values range are corresponding magnetic 0.86 lower to moments moments of to 1.55 than the one unpaired can be present B.M., copper(II) at room spin only value electron. interpreted in complexes temperature. (1.73 These terms copper-copper interaction or complexes may exist B.M.) subnormal of direct in polymeric form. Lanthanide(III) complexes Magnetic moments of lanthanide(III) in Table III. the and The observed magnetic moments are compared with theoretical the complexes are shown values spin-orbit calculated 50 coupling values from Van Vleck (the Hund values) formula of the respective lanthanide ions. These values agree with each other except for those of the Sm(III) and Eu(III) complexes. However it is found that the experimental values of all the complexes including those of Sm and Eu agree with the theoretical values calculated from Van Vleck formula. Electronic spectra Cobalt(II) complexes Cobalt(II) ion belongs to d 7 electonic configuration and can form both tetrahedral and octahedral complexes. number of six coordinate octahedral cobalt(II) In a large complexes, three spin allowed d-d transitions in the order of increasing energy are given as follows. 41 (F) 4 4---- Tn lg 2g — 4t (F) 4— 2g 4. ' ig 1 (F) (V_ 2 ig -5---- (p) (V (F) 4t (F) ig (v 3 A band in the range of 7000-10000 cm to v admixture (F) lg can be assigned transition while a multiple band observed in the visible region near 4T -1 18000 with cm spin -1 may be forbidden assigned to transition. transition The 4v A^tF) 2g m 4 (v ) transition is not normally observed as it is a two 2 51 Table III Magnetic moment of lanthanide(III) nitrate complexes with MPSMT Complex code Complex Exptl. value (B.M) Hund's value (B.M. ) Van Vleck and Frank's value (B.M.) ------B1 [La(MPSMT)2N031.HO 0.00 0.00 0.00 B2 [Ce(MPSMT)NO ].HO 2.46 2.54 2.55 B3 [Pr (MPSMT) 2N03] .2^0 3.66 3.58 3.62 B4 [Nd(MPSMT)2N03].3H 0 3.66 3.62 3.68 B5 [Sm(MPSMT) NO ].3H 0 1.25 0.84 1.65 B6 [EU(MPSMT)2N03].2H20 3.25 0.00 3.40-3.51 B7 [Gd(MPSMT)2N03].2H 0 7.69 7.94 7.94 B8 [Tb(MPSMT)2N03].2H 0 9.64 9.53 9.52 B9 [Dy (MPSMT) 2NC>3] .2H 0 10.04 10.63 10.62 bio [Er(MPSMT) NO.].2H 0 2 3 2 [Yb(MPSMT) NO ].2H O 2 3 2 [Y(MPSMT)2N03].2H 0 9.60 9.57 9.60 4.89 4.50 4.54 0.00 0.00 0.00 B11 B12 52 electron transition in the strong field. energy of different transitions in The equations for the the weak ligand field coupling are given below. v = 1/2(10 Dq - 15 B') + 1/2 [10 Dq + 15B') 2 - 12B'.10 Dq] 1/2 ' v2= 1/2(30 Dq - 15 B') + 1/2 [ (10 Dq + 15B') 2 - 12B'.10 Dq] 1/2 ' v3= [(10 Dq + 15 B')2 - 12 B',10 Dq]1^2 The values of the ligand field parameters such as Dq, B' and b can be evaluated using three d-d transitions employing any one of the following methods. a) by fitting v and transitions 10 Dq = v2 . V;l B' = (vx2 - vx v2) / (12 v2 - 27 vi) b) by fitting v and -v 10 Dq M = 2v, 1 B' = 1/30 transitions - v.3 + 15 B' [ — 2iv - v ) + (-v 2 + v3 2 + v v ) 1/2 ] The reddish-brown coloured cobalt(II) complexes C? and C ) 7849-8130 cm (C , C . 14 showed two d-d bands in the range 19,600-20,830 and -1 4 which are assinged to T lg 4 (P)<—— T lg (F) (v ) and 3 4T (F)<--- 4 T (F) (v ) transitions of octahedral cobalt (II) 2g lg 1 ion 102 . The vband which involves two electron transition was not observed using Konig's (Fig. 1) . However, equation. its The various 53 position was calculated ligand field parameters Fi«. 1 . Electronic spectrum of lCo(lfliAIIT)Cl (H O) 03 L o o aOmfHHOSSV ro like Dq, B' , p and LFSE have been calculated and are given in Table IV. The v /v ratio agrees well with reported values for octahedral cobalt(II) complexes. Nickel(II) complexes Nickel(II) nickel (II) large ion complexes number of has are d 8 of electronic particular stereochemical octahedral nickel(II) forms. configuration. interest The The because of spectra of complexes exhibit three spin allowed d-d transitions. ■tm 3Tlg 3T2g *29 Three spin allowed transitions in increasing order of energy are designated as 3A2g(F) 2g(p,^- 3Vf) 3Vf> (v^ (v3) The present paramagnetic nickel(II) complexes C , C^, Cg 54 Table IV Electronic spectral data of octahedral cobalt(II) and nickel(II) complexes (in DMF) Complex V2 V1 Complex code cm -1 V2 calc . -1 cm cm -1 Dq cm -1 B1 cm 3 Vi -1 LFSE k cal mol 1 [Co(MMAMT)Cl. (H2°)j ^ 8130 17433 20830 930.5 925.0 0.952 2 . 14 21.2 [CO(MPAMT)Cl. (H O) ] 7843 16801 19646 895 . 8 861.0 0.887 2 . 14 20.5 S [Co(MMSMT)Cl.(H^O)j) 7547 16193 19608 864.6 877.6 0.904 2.15 19.8 cio [Co(MPSMT)Cl.(H20) ) 8130 17434 20833 930.4 925.1 0.953 2 . 14 2 1.3 C2 [Ni(MMAMT)Cl.(H20) ] 8969 14368 24096 896.9 770.5 0.740 1.68 30.75 S [Ni(MPAMT)Cl.(HO) 8696 15267 23529 896.6 847.2 0.814 1 . 76 29.81 C8 [Ni(MMSMT)(HO) 10695 17637 24691 1089.5 682 . 9 0.65 1 . 65 35.5 C11 [Ni (MPSMT) (H20)2 3 10753 17762 25126 1075.3 708.6 0.68 1.65 36.9 C C 1 4 ] Free ion value for cobalt(II) Free ion value for nickel(II) 55 = 971 cm -1 , * 1041 cm 1, LFSE « 6 Dq; 350 cm , LFSE - 12 Dq -1 ■ 1 K cal mol and C and 3m T exhibit three bands at 8696-8969 cm 23529-24096 2g 3 (F) *--- A 2g respectively, nickel(II) 0. by attributed cm 3 (F) , which T lg 3 (F)<--- A indicates 2g the -1 , to . and (F) 1 14368-15267 cm the 3 T octahedral transitions lg r 3 (P,i4--- A 2g (F) geometry around ion. The various ligand field parameters like Dq, B' v2/v1 and LFSE have been computed using the method described Drago 103 . The values are tabulated in copper(II), a Table IV. The spectrum is reproduced in Fig 2. Copper(II) complexes The orgel diagram for inverted diagram of d1 as shown below. (t- 5e ) 2g g (t 2g 6e ) g may be with D symmetry symmetry the E * g or and T 2g rhombic levels of 9 ion is an The electron transition considered All six coordinated copper(II) d as positive hole complexes are tetragonal with symmetry In D 4h D free ion term will further 56 V. . FiR. 2 Electronic spectrum of [Ni(MMAllT)Cl (H 0) split into Blg, Alg and B2g, Eg levels respectively. The energy level sequence will depend on the amount of distortion due to ligand field and Jahn-Teller effect. Hence three spin-allowed transitions are expected in visible and near IR regions for a copper (II) complex in D or C symmetry. complexes C_ and C show (Table V) a very broad band of low 3 6 intensity in the region, 17200-17391 cm ^ which can be assigned 2 104 4-—- E transition . In addition to this another band 2g g in the region 23529-24691 cm 1 is also seen. This band may be to 2 t due to symmetry forbidden ligand ---- vmetal charge transfer The band observed above band. 2700 cm 1 may be assigned as 105 ligand Distorted octahedral structure has been proposed on the basis of electronic spectra. The electronic and C spectra of the copper(II) complexes Cg exhibit a broad asymmetric band in the region 16130- 57 Table V Electronic spectral data of copper(II) cmplexes in DMF solution. Complex Complex X max (nm) code C3 C6 [Cu(MMAMT)Cl.HO] [Cu(MPAMT)Cl.HO] 58 X max (cm X) Assignments 2_ T , 2_ <--- E 580 17241 405 24691 C T 330 30303 Ligand 575 17391 425 23529 C T 340 29411 Ligand 2g 2t g ^____2e 2g g 16080 cm 1 which could be attributed to the d-d transitions. In addition region to this, 25000-24560 a cm charge transfer band. high -1 intensity band observed could be considered as in the ligand-metal On the basis of electronic spectra, a distorted octahedral geometry may be proposed. complexes Lanthanide(III) The important electronic MPSMT and lanthanide(III) assignments are ligand exhibits cm _ spectral bands in Table VI. * and n—> n * one being more intense than the former. complexes. No lanthanide(III) The two UV absorption maxima suffer a slight blue the ligand complexes along with their tentative presented assignable to n—> n of shift at due to 30156 transitions. However, in the spectra of absorption band spectrum f-f of and the 37147 The latter these bands lanthanide(III) transition of the ions could be identified in the visible region in the spectra of all these complexes. This is probably due to the fact that the f-f bands are weak and are obscured by the intense charge transfer bands 59 106 Table VI Electronic spectral data of lanthanide(III) complexes with liaand MPSMT SI.NO. Complex 1 MPSMT X max cm Assignments 3 * 30156 37147 2 3 ■k [La(MPSMT)2N03] •H2° [Ce(MPSMT)2N03] •H2° 30242 n'------V 77 37272 71 77 30185 n n * ★ * 37345 71 * 4 [Pr(MPSMT)2N03) •2H2° 30864 TV 35161 71 * 71 ■k n k 5 [Nd(MPSMT)2N03] . 3H 0 2 30382 77 37148 71 30487 71 k * 6 [Sm(MPSMT)2N03] . 3H 0 2 * 37037 71 77 k 7 [Gd(MPSMT)2N03] • 2H 0 2 30317 77 37548 77-------^77 30244 n- k k 8 [Tb(MPSMT)2N03] . 2H 0 2 ■*77 * 37375 77 k S [Dy(MPSMT)2N03] . 2H 0 2 30198 n- * 77 37215 77- *77 * * 10 [Er(MPSMT) NO ] . 2H 0 2 3 2 30164 * 77 O * to [Yb(MPSMT)2N03] to 37350 11 77 30275 77 * 37285 77 '77 k 12 [Y(MPSMT)2N031 • 2H 0 2 60 30284 ■77 37265 77 * Infrared spectral studies i) IR studies of MMAMT and MPAMT and their cohalt (II), nickel(II) and copper(II) complexes: The infrared frequencies of selected spectra of MMAMT and MPAMT as well as groups in the in their corresponding complexes are tabulated in Table VII. The spectra are presented in Fig. 3 to 7. The bands at 3271 and 3141 cm 1 and the band at 2570 v(SH) cm "'’in MMAMT and MPAMT have been assigned to modes 103 respectively. Y(NH) and The high intensity bands in the region 1622-1604 and 1579-1567 cm 1 could be assigned to vC=N frequency of triazole moiety. The three strong bands at 1510, 1307 and 1030 cm 1 have been respectively assigned to thioamide bands 107 cm _ i is band (IV) (I) , (II) assigned and (III) . to N-N A medium intensity band at 900 stretching vibration. The thioamide which is mainly due to >C=S stretching vibration is observed at 750 cm 1. The IR spectra of cobalt(II), complexes with MMAMT and 3430 cm"1 due to v(OH) MPAMT nickel(II) and copper(II) showed a broad band around of coordinated water. The NH stretching frequency observed at 3271 cm 1 in the ligands have shifted to 3221 cm"1 in the complexes suggesting the coordination of amino group to metal(II) ion. The 61 v(C=N) frequency of triazole Table VII Infrared frequencies . Complex (in cm 1i of Coin! Ni(II) and Cu(II) complexes with MMAMT, MPAMT . and MPSMT along with their assignments Ligand/Complex V(OH) of V(NH) code V (SH) V(C=N) Thiamide V(C=S) 1604 1307 750m 1300 750m V(M-O) V(M-N) water B1 MMAMT B2 MPAMT 3271 2570m 1567 3141 3252 2 5 7 Ow 1622 1910 3141 S [Co(MMAMT!Cl.2H^01 3425br 3200 --- 161Obr 1400 680m 4 70m 520m C2 [Ni(MMAMT)Cl.2H^0] 3 4 0 Obr 3200 --- 1617br 1401 675m 4 8 5m 510m C3 [Cu(MMAMT)Cl.H2OJ 3 4 3 Obr 3200 --- 162 Obr 1405 675m 4 80m 485m c [Co(MPAMT)Cl.2H 0] 3 4 0 Obr 3150 --- 16 2 9br 1400 670m 460m 480m cs [Ni(MPAMT)Cl.2H20] 3 4 0 Obr 3221 --- 163 Obr 1405 665 4 8 5w 5 0 0m C6 [Cu(MPAMTC1.HO] 3 4 2 5br 3147 --- 163 Obr 1407m 6 8 0m 485m 54 3w 4 V (OH) of water B3 MMSMT B MPSMT 4 --... V {OH} of V(NH) V(SH! V(C-N) phenolic V(C-O) V(C-S) V(M-O) phenolic 2750 3105 2300 1612s 12 50 755 2765 3105 2360 1610s 1250 755 --- 1600s 1285 6 8 0m 4 8 0m S [Co(MMSMT)(H20) ] 3400 --- 2935 C8 [Ni(MMSMT)(HO) 3425 --- 2930 ... 1605s 1285 685m 485m S [Cu(MMSMT] --- 293 5 ... 1600s 1270 685m 4 8 5w cio [Co(MPSMT)(HO) ] 3400 --- 2931 1603s 1280 6 75w 480m C11 [Ni(MPSMT)(H20) ] 3410 --- 2924 ... 1600s 1285 675w 480m C12 [Cu(MPSMT)] --- --- 2931 ... 1600s 1282 6 8 0m 4 85w ] ... 62 --- CM CM Wavenumbers (cm-1) *c M n be **■4 »I j i» t! Ui I cd \ co T i [Til i | i i i i | i i i i | i i i i j IO o o in 8 CO in in rr in o xr in co aOUBU!UJSUBJl% o co in CM rrr “ o in F ig . 4 IR s p e c tr u m o f rC o(10IA IIT )C l . (H O) moiety observed in the region 1622-1604 and 1579- 1567 cm 1 in the spectra of the ligands have shifted to around 1630 cm 1 in the complexes. This observation indicates the coordination of one of the azomethine nitrogen of triazole moiety to the metal atom. The shifting of IR band of v(c=N) towards higher wave number is due to the delocalisation of the charge between N, C and S of triazole moiety in the ligands to only N and C in the complexes. The band due to v(c=S) observed at around 750 cm 1 _i in the ligands undergoes red shift by 70-80 cm ~ in complexes. This indicates the coordination of sulphur atom via , . 108 deprotonation ii) IR studies of MMSMT and MPSMT nickel(II) and copper(II) complexes: and The MPSMT exist both in thiol and thione form. 3105 cm 1 due to V(NH) their ligands cobalt (II), MMSMT and A broad band around indicates the thione form where as a medium intensity broad band in the 2360-2300 cm 1 region due to v(SH) region represents 2765-2750 bonding. the cm -1 is form. due to A broad weak band the intramolecular in the hydrogen The high intensity band in the region 1612-1610 cm 1 is assigned to V(C=N) assigned thiol to v(c=N) group and a strong band at 1575 cm 1 is of triazole ring . A band m the _i region 1530-1510cm is 63 due to v(C-0) of phenolic group. 500 1000 _______ \ 3500 3000 \ 52 ji \ 1»'11 jTT. JrrriTTT^TTTJTTT^ t i * i i f jTTTjTM 'iTtT"J"7TT”|T'."i'j"iTTITTTT; ? i * > f i’^mTTTTTTH^T i > j <; ijT77y77TJ7,!T|T77ijT7?^^ O00<D^rC'IOG0<D^<NOC0CDrfr4O00C0^(NOC0<D^fCNOC4 lD-’«l‘^^r ^r^J-<0<0<OCOCOC'4<NC4<NCNT-T- aouewiuiSUBJi% r- r~ r~ ' Wavenumbers (cm-1) 1500 2000 2500 \ Another band of high intensity around 1250 cm the same phenolic C-0 vibration. the region 755 cm -1 and 3425 cm 1 due to v(OH) bonded phenolic C-0 OH MPSMT in the show a ligands appears corresponding complexes. In copper(II) oxygen bridge complexes the positive observations oxygen atom of whereas in of . band around The band due to 1285 cm and -1 the new all the in complexes the band due shows a positive shift of cobalt(II) is of that in and the order of the nickel(II) 10-15 copper(II) cm 1. complexes the ligand shows bridging bidentare behaviour cm 1 and The nickel(II) V(C=N) indicating complexes exhibits for these complexes appears coordination of azomethine The strong band at 1575 cm 1 due to VC=N vibrations triazole ring in the complexes. In shift cobalt (II) 1600 nitrogen. 99 suggest monodentate behaviour. around broad , thus offering an unambigous proof for the phenolic These -1 and copper(II) disappears around to the phenolic OH at 1530-1510 cm -1 nickel(II) of coordinated water. vibration the order 25-35 cm 99 has been assigned to the V(C=S) MMSMT hydrogen is assigned to The medium intensity band in The IR spectra of cobalt(II), complexes with -1 This ligands undergoes blue indicates triazole with metal ion . 64 the bonding of ring shift in the nitrogen of In all the complexes the band m the region 2360-2300 cm 1 due to V(SH) disappears and the other due to iv(C=S) becomes 685-675 cm 1. weak and shifts to lower This confirms the participation of wave number -SH group in coordination. iii) IR studies of MPSMT and its lanthanide(III) complexes: The assignment of IR spectral bands of the ligand MPSMT is described in the previous paragraph. of MPSMT and its lanthanide(III) VIII. In lanthanide (III) The IR spectral data complexes are given in Table complexes, the v (NH) and v(sh) bands appear at the same region as in the ligand. The position of the band at 751 cm 1 due to v(c=S) the This indicates complexes. taken part in the of the ligand is unaffected in that coordination the sulphur to the atom has not metal disappearance of the broad weak band around 2765 intramolecular shifting frequency H-bonding to the azomethine band due to phenolic v(c-O) from 1250 cm 1 1286 cm 1 cm -1 nitrogen of the to ion. The due to and to the the higher indicates the coordination of phenolic oxygen of the ligand to the metal via deprotonation. v(c=N) of The shifting of the ligand from 1610 cm 1 to 1628-1647 cm 1 in the complexes accounts for the participation of coordination111. theazomethine nitrogen in The broad absorption peak at 3438 cm 1 in the lanthanide (III) 65 90UBU!LUSUBJ1% I 1 ' . ..... ......I 2500 2000 Wavenumbers (cm-1) Fig. 6 IR spectrum of [Ni (MIIAMT)Cl 3000 (HO) . 1500 1000 65 H -i -\ 0 - 5- 10 15 20 25 30 35 40 i—Sfr l-o$ 55 09 aoue}}!iusuejj_% Fij?. 7 IH sp e c tr u m o f IP r(llP S lIT ) NO 1H O Table VIII Important IR frequencies Compound Compound V(OH) v(OH)of (cm 1) V(NH) of the ligand V (SH) V(C=N) (MPSMT) V(C = S) and lanthanide(111) V(C- 0)phenolic V4 code vi N03 V2 of water phenolic 2765 MPSMT 3105 2306 1610 756 1250 complexes V6 V3 V_ 3 1 [La(MPSMT) NO ]H 0 2 3 2 3431 - 3036 2371 1647 751 1260 1530 1315 1025 840 725 678 B2 [Ce (MPSMT) 2NC>3 ] H20 343 1 - 3 03 6 2370 1634 751 12 82 153 0 1320 1030 899 725 680 B [Pr(MPSMT)2N03]2H20 3431 - 2 913 2370 1647 751 12 82 1530 1315 1030 842 72 5 680 [Nd(MPSMT)2N03)2H20 3388 - 3060 2 3 80 1621 751 1282 1526 1320 1035 899 725 689 [Sm(MPSMT) NO ]3H 0 3406 2 3 2 - 2931 2370 1628 763 1282 1520 1320 1035 899 725 677 B6 [Eu(MPSMT) NO )3H 0 3425 3 2 - 2 944 2360 1628 764 1282 1530 1320 1030 850 725 677 B (Gd(MPSMT)2N0312H20 3438 - 2 944 2370 1634 751 1276 1520 1301 1054 825 725 678 [Tb(MPSMT)2N03]2H20 3431 - 3 036 2 3 86 1629 752 1270 1536 1320 1030 901 72 5 684 [Dy(MPSMT)2N03]2H20 33 94 - 303 6 2356 162 8 751 1270 1536 1314 1030 894 730 677 [Er(MPSMT)2N03]2 H2 0 3431 - 2930 2 3 80 1634 751 1282 1530 1320 1035 906 72 5 680 [Yb(MPSMT)2N03]2H20 3413 - 2930 2370 1634 758 1276 1530 1320 103 5 906 725 680 [Y(MPSMT)2N0312H20 - 2930 2380 1634 758 1275 153 6 1326 1030 906 725 689 B B B B B B B B 3 4 5 7 8 9 10 11 12 2 343 8 66 t-54Q3 complexes indicates the presence of water molecule(s). This was further confirmed by TG studies. The nitrate in metal complexes is present either as an ionic species or coordinated one. Further, if it is coordinated, it may act as monodentate or bidentate ligand. The infrared spectra contributed sufficient information regarding the behaviour of the NO^ group. Nitrate ion can be bonded to a metal ion in three different ways as shown below. When nitrate ion acts as a coordinating agent, a) the symmetry of the ion is lowered to C b) all six normal modes of vibration become IR active c) shifts in band position occur and d) the degenaracy of and is lifted. For uni and bidentate coordination of the nitrate ion, the made symmetry remains a detailed study the 112 same of (C the ) ' anc* Curtis IR spectra of with uni and bidentate nitrate ions. splitting of the degenerate Curt:*-S the have complexes They have found that the vibration of the free nitrate ion is of the order of 100-150 cm 1 for unidentate coordination and 190-220 cm 1 lanthanide(III) for bidentate coordination. The present complexes show six absorption bands near 1486, 67 1290, 1030, 860, 758 Y coordinated v -v (C,^) and V2' nitrate 700 v 6 group. cm 1, v_ 3 and The i v magnitude of v. -v and are in the range of 196-209 and 58-65 cm \ respectively. This confirms the coordination of nitrate group in bidentate _ . . 113,114 fashion Electron spin resonance spectra The (ESR) fundamental principle of electron is essentially the same as that of NMR. spin resonance The practical difference arises from the fact that the magnetic moment of an electron is substantially larger than that of a proton. The energy of resonance absorption is hE = hv = gpH, where v = Frequency of radiation h = Plank's constant g = Spectroscopic Splitting Factor p = Bohr magneton H = Magnetic field. The ESR instruments are operated in the region of 9200 MHz with the corresponding field intensity - 3000 gauss. to the orbital moment contribution, 68 Owing the value of g will differ from 2.0027. The value of g in any arbitrary direction can be expressed as the resultant of the tensor components q , q and x y g corresponding to the direction of the x, y and z axes. The z average value (g g = 1/3 (g av ) is given by the relation. + g x + g y ) z measurements on homogeneous powder sample give g and g values only as observed in the case of complexes under study. The position of g^ and g diphenyl ethylene radical values picryl (TCNE). are hydrazyl The g Blumberg to the procedure with (DPPH) and g « according compared or resonance tetracyano values are calculated 1 indicated by peisach and recorded both room 115 9„ °r 9TCNE X H (TCNE) H (9tcne = 2'0027) 9 ESR spectra of the a, - complexes 1/3 <9« + 29' were temperature and liquid nitrogen temperature. ESR spectra of the polycrystalline Cu(II) complexes are shown in Fig. 8 to 11. The g values obtained from the spectra are represented in Table IX. From the observed g values g(j > g > gg 69 (2.0027), it is Fig. 8 ESR spectrum of [Cu<miAMT)Cl.H_0] SCAN RANGE Fig. ESR spectrum of [Cu(llllAMT)Cl.Il201 in polycrystalline state at LNT 9 SCAN RANGE FiR. . in polycrystalline state at RT lo ESR spectrum of [Cu(MPSllT)Cl H^Ol SCAN RANGE FiR. in polycrysta 11 ESR spectrum of SCAN RANGE [cudiPsimei.H oi evident that the unpaired electron lies predominantly in the d^2_^2 orbital with the possibility of some dz2 character being mixed with it because of low symmetry In axial symmetry the g 11.6 values are related by the , 117,118 expression (9|j- 2) G = ----------------- (g - 2) -L which measures the exchange interaction between copper centers in the polycrystalline solid. According value of G is greater than four, negligible, where considerably complex. as In the interaction present Hathway if the the exchange interaction is when the value exchange to is of G is less indicated investigation, all in than the four solid copper(II) complexes have G values in the range 2.72 to 3.9 indicating the interaction of copper centers which is also supported by subnormal magnetic moment. Metal-ligand covalency For a planar D4h copper(II) complex Kivelson and Neiman showed that for ground state vy = a . _ + ligand terms a 2 2 x -y where a is the coefficient of the ground state ^x2_y2 orbital an estimate of a 2 could be obtained using the expression: 70 Table IX ESR spectral data of copper(II) Complex Complex code RT ..... .... ....... .......... 91| S C6 [Cu(MMAMT)Cl.HO] (Cu(MPAMT)Cl.HO] 9 C12 [Cu(MMSMT)] [Cu(MPSMT)J gj_ gav . -a x 10 , in cm * a2 2.257 (2.289) 2.110 (2 . 103) 2.159 (2.165) 2.040 2.015 {2.015) 2.023 102.8 0.385 2.7 (2.025) (119.4) (0 .331) (3.1) 52 . 1 (53.6) 0 . 145 3-2 (0.164) (3-3) 0.544 (0.480) (3.9) (2.047) c complexes in solid state 189.7 0 . 527 2 .7 (192.4) (0.534) (2.8) 2.216 2.073 2.134 (2.223) (2.075) (2.134! 2.254 2 . 065 (2 . 065) 2.123 195.9 (2.136) (173 .0) (2.277) The values in parenthesis are at LNT. 71 3 .8 “2 = o 03i~+ (9« " 2'0027) + 3/? (9 - 2.0027} + 0.04 -L This relation has metal-ligand covalency, D4h Here a been widely employed as measure of even for the complexes not possessing 2 is the residence time of unpaired electron on ‘copper (II) ion. The a range of 2 values 0.145 to for the 0.544 present complexes indicating fall covalent in the nature of copper(II) and ligand bonds. Kivelson and Nieman 118 have shown that the g() moderately sensitive function of metal ligand covalency. ionic environments gMis covalent environments it normally 2.3 is or larger and less than 2.3. is For for more So the g^ values 2.04 to 2.28 for the complexes under investigation also impute that the complexes are covalent in nature. Proton magnetic resonance studies The proton magnetic MPSMT and its lanthanum(III) resonance spectra of the ligand complex were recorded in DMSO-d O solvent . The chemical shift values 8 (in ppm) are given in the Table X and spectra are presented in Fig. 12 and 13. The protons of piperidine ring appeared as multiplet in 72 the region 8 1.98-2.40 ppm (5, 1.98, 6H, d, CH -CH -CH ; 2.40, 2 2 2 4H, d, H^C-N-CH^). A singlet observed at 5 3.27 ppm is methylene protons. The presence of NH and SH peaks indicate thiol-thione tautomerism in the protons. spectrum 8 6.70-7.66 ppm The singlet due to lanthanum(III) phenolic peak phenolic complex. oxygen deprotonation. to Two singlets at § 11.16 and § 2.50 ppm are due to NH and SH protons respectively. multiplet at due in The (m, at -OH This 4H, 8 Ar-H) 12.06 group coordination singlet at 8 the ligand observed the with observed in not confirms The is due to aromatic ppm is ligand. in the involvement the of metal 8.43 ppm via due to azomethine proton of the ligand has undergone down field shift to 8 9.00 ppm in the spectrum of lanthanum(III) confirms deshielding as nitrogen of the a result of azomethine group complex. This coordination through the to the metal ion. The resonance due to the NH proton of the ligand at 5 11.16 ppm is unaffected in the spectra of lanthanum(III) complex. This suggests -SH group of the tautomeric form of the ligand has not taken part in coordination. 73 'ftfc91JNI u .c u .s FiR . 12 H NMR spectru in o f MPSIIT 0.03 14 13 12 Fiff. 11 13 10 0.05 a ~T~ 0.05 -0.00 0.10 H NMR spectrum of 1 PULSE SEQUENCE Relax, delay 1.000 sec Pulse 54.0 degrees Acq. time 1.500 sec Width 4000.0 Hz 64 repetitions OBSERVE HI, 199.9760221 KHz DATA PROCESSING Line broadening 0.1 Hz FT size 16384 Total time 2 minutes ------ flC ASP1 23/6/98 Solvent: dmso Ambient temperature GEMINI-200 M c1ba" [La(lIPSllT) 0.16 NO 1H_0 0.08 0.19 0.00 v * . 0.24 A £ f CL Q. Table X 1HNMR spectral data of ligand MPSMT and its Lanthanum(III) complex 5 in ppm Ligand Complex Assignements 1.98-2.40m 1.98-2.40m -6H piperidine ring protons 6.70-7.66m 6.70-7.66m -4H aromatic protons 3.27s 3.27s -CH - proton 2.50s 2.50s -SH- proton 8.43s 9.00s -N=CH- azomethine proton 11.16s 11.16s -NH (hydrazine-NH) proton phenolic -OH 12.06s s=singlet m=multiplet 74 proton Thermal studies There are various thermal analysis techniques currently employed, which thermal include analysis differential analysis (DTA), scanning (EGA). thermogravimetry derivative calorimetry (TG), differential thermogravimetry (DSC) and (DTG), evolved These techniques provide valuable gas information about a given substance. Of the various thermal analysis techniques, the most widely used techniques are TG and DTA. Thermogravimetry (TG) is the technique, in which the change in mass of a substance in an environment heated or cooled at a controlled rate is recorded as a function of time or temperature. Such a record is called a thermogravimetric or TG curve. One of the most important applications of TG technique is to know the thermal stability of a given substance with a view to ascertain its weighable form in conventional gravimetric method. factors that affect The most the pattern of TG curve are important the heating rate and the sample size. In the present investigations, TG measurements of cobalt(II), nickel(II), copper(II) complexes of MMAMT and MPAMT and lanthanide(III) complexes of MPSMT have been carried out in static air, using limiting 75 temperature of a 900 C and heating rate of 10 C/min. weight loss as The TG curves were analysed as percentage a function of temperature. The number of decomposition steps were identified using a derivative of TG curves. Typical thermogravimetric curves are shown in the Fig. 14 to 17. The steps. of MMAMT and The first step at 35-310°C, between water complexes 16.20-20.10%, and chloride decomposition the MPAMT to molecule. In is lost loss of one stable two the between coordinated second the step of temperature ° of O 211-850 C. plateau in with a weight loss ranging corresponds ligand decomposes is There is no further weight loss beyond 850 C and a obtained metal calculated oxide form TG which corresponds (Table studies to the formation XI). The percentage agrees well with the of of metal theoretical results within the experimental errors. In temperature case of of lanthanide(III) decomposition, the complexes of MPSMT the pyrolysed products, the percentage weight loss of the ligands, and the percent residue are given in Table XII. The lanthanum(III) e weight loss of 2.03% at 80-120 C complex which indicates of one uncoordinated water molecule in the lattice the second stage, the weight loss of 81.48% 76 shows a the presence (2.11%). In (calcd.81.59%) in Table XI Thermogravimetric data of Co(XX),Ni(XX) and Cu {11) complexes of MMAMT and MPAMT Complex Temperature Process Product o range/ C (CoIMMAMT)Cl.2H^0] Dehydration & Decomposition Weight % Calc. Expt. No. of moles H2 0 & 40 - 280 Cl 20.74 20.04 1 62.11 61.74 1 20.78 21.28 62.74 62 . 83 16.16 16.70 65.25 65.84 20.87 19.74 62.18 61.41 19.95 20.10 61.74 62.41 16.76 16.04 64.75 63.84 of coordination sphere (L, Cl) (NilMMAMT)Cl.2H^O} 281 - 640 Dehydration & Decomposition H 0 & 2 2 35 - 250 Cl 1 of coordination sphere (L, Cl) (CuIMMAMT)Cl.H20J 251 - 580 HO & Dehydration & Decomposition 1 2 40 - 262 Cl 1 of coordination sphere (L, Cl) (CoIMPAMT)Cl.H20) 263 - 688 H 0 & Dehydration & Decomposition 2 40 - 230 Cl of coordination sphere (L, Cl) (Ni< MPAMT)Cl.HO] 231 - 850 H20 & Dehydration & Decomposition 50 - 220 Cl of coordination sphere (L, Cl) [CuiMPAMT)Cl.HO] 221 - 550 H 0 & Dehydration & Decomposition 1 2 70 - 310 Cl of coordination sphere (L, Cl) 77 311 - 720 1 Table XII Thermogravimetric data of lanthanum!111) , neodymium(111) and dysprosiumi111) complexes Complex Process Decomposition Temperature range (°C) [La(PSMT)2no3]h2° Dehydration Decomposition 80 - 120 121 - 540 of coordination Decomposition Product H2° 2 PSMT Sc Weight loss No.of Obs. Calc. moles 2.11 2.03 1 01.59 81.48 2 N°3 1 sphere {2 PSMT,NO ) [Nd(PSMT)2N0312H20 Dehydration & 55 - 196 H2 0 Sc 10.86 10.78 2 Decomposition of coordination NO 1 3 sphere {NO ) of Decomposition 197 - 300 PSMT 35.57 35-38 1 PSMT 35.57 34-64 1 9 .02 9.23 coordination sphere EPSMT) Decomposition of coordination sphere (PSMT) [Dy (PSMT) 2N031 21^0 Dehydration & 40 - 210 H2° Decomposition of no3 coordination 1 sphere (NO ) Decomposition of 211 - 295 PSMT 3 5.55 3 5.18 1 PSMT 35.55 3 5.43 1 coordination sphere (PSMT) Decomposition of coordination sphere {PSMT) 78 *TM F i* . 1 4 T .G . c u r v e o f [M iO M A M D C l. O t^ l pf m N* Tem p. 06 C O O 880J F i« . 1 5 T .G . c u r v e o f C C u O U IA M D C l.^ O l Tem p. Temp. F i r . 16 T.G . c u rv e o f [La(lIPS»IT> 2 N03 lH 20 PlbAKU CAT. NO 9004CG ssoi F iR . 17 T .G . c u rv e o f IH d d lP S lfD ^ U ^ O Temp. o the temperature range 121-540 C indicates nitrate and two ligand molecules. The the loss of one plateau obtained beyond O 540 C indicates the formation complexes of neodymium(III) of stable La O . 2 3 and dysprosium(III) In the the first step O of decomposition occurs between 55-196 and 40-210 C with weight loss of 10.78 and 9.23%, respectively. This corresponds to the loss of two uncoordinated water and nitrate molecule. In second O O step, decomposition occurs between 197-300 C and 211-295 C, and this decomposition accounts for the loss of one ligand O molecule. In third step, decomposition occurs between 301-626 C O and 296-690 C, another and this decomposition accounts for the loss of ligand (Table XII) molecule. The percentage of metal obtained by this method is in good agreement with that of the EDTA titration method followed. kinetic studies of cobalt(II), nickel(II) and copper(II) complexes with MMAMT and MPAMT The thermograms obtained during TG scans were analysed to give the temperature. (temperature c percentage weight Tq (temperature of for 10% weight loss as a function of onset of decomposition), T^Q loss) and T max (temperature of maximum weight loss) are the main criteria to indicate the heat 79 stability of the complexes. and T The higher the values of Tq, T , the higher the heat stability, max Broido's method was used to evaluate the kinetic parameters from the TG curve. Using Broido's method, plots of In (In 1/y) vs l/T (where y is the fraction not yet decomposed) for different stages of the thermal degradation process of the complexes were made 19. Fig. (Table XIII) and are shown in Figs. 18 and 18 is first step of the degradation and Fig. 19 the second step of degradation. In order to determine the thermal parameters T , T1Q/ Tmax' stability trend, activati°n energy (Ea) the and frequency factor (In A), were evaluated and are given in Table XIV . The thermodynamic parameters, # (AG ) , enthalpy entropy # (As ) and free energy (AG ) of activation, were calculated using standard equations and the values are given in Table XV. 11 The indicates possible ASff a values more through have ordered the found to activated chemisorption decomposition products 119 ' 120 . be state of negative, which oxygen than that for the first stage which 80 might and be other The energy of activation values for the second stage of decomposition were found to decomposition of second stage which is be higher indicates that the rate of lower than that of first lr<lnl/^ to o a to — t H n Indnl/Y) M aw* to O to O H — <N a > Fig. 19 Plots of ln(ln 1/y) vs. 1/T for the second degradation process of (A) [CoCMMAMDCl. (H20>21; (B) [Ni(10IAMT)Cl. <H20)21 (C) [Cu(I0IAMT)C1.H201; (D) [Co(MPAMT)C1 . (H20>21; (E) [Ni(10IAMT)Cl.(H20)2l; (F) lCu«OiAliT)Cl.H Ol Table XIII Kinetics of decomposition studies on cobalt(II), nickel(II) and copper(II) complexes of 3-substituted4-amino-5-mercpto-l,2,4-triazole Complex code C1 C2 Stage Complex [Co(MMAMT)Cl.2H20] [Ni(MMAMT)Cl.2H0] 81 In(In 1/y) 1/TxlO3 -0.7320 3.1948 -0.7260 -0.7229 -0.7135 -0.7038 -0.7005 -0.6972 -0.6729 3.0487 3.0030 2.9154 2.6809 2.5839 2.4813 2.0202 -0.6185 1.7636 -0.6100 -0.6013 -0.5923 -0.5831 -0.5737 -0.5640 -0.5541 1.7513 1.7331 1.7211 1.7094 1.6891 1.6778 1.6638 -0.7198 2.9154 -0.7136 -0.7071 -0.7005 -0.6620 -0.6583 -0.6507 -0.6429 2.8328 2.7548 2.6954 2.2573 2.1978 2.1141 2.0618 -0.5541 1.7574 -0.5462 -0.5225 -0.5200 -0.4999 -0.4881 -0.4366 1.7391 1.7094 1.6920 1.6722 1.6583 1.6051 c3 [Cu{MMAMT)Cl.H O] I II C 4 [Co(MPAMT)C1.2H Oj I II C [Ni(MPAMT)Cl.2H 0] I -0.7198 3.0487 -0.7135 -0.7071 -0.7005 -0.6940 2.9154 2.8328 2.7548 2.2809 -0.6269 1.7921 -0.5923 -0.5541 -0.5334 -0.4501 -0.4336 1.7513 1.7035 1.6778 1.5797 1.5552 -0.7320 3.1545 -0.7260 -0.7198 -0.7071 -0.7005 -0.6964 -0.6870 3.0581 3.003 2.8818 2.8328 2.7855 2.5773 -0.4632 1.6583 -0.4366 -0.4081 -0.3774 -0.3442 -0.2889 -0.2475 1.6240 1.6103 1.5898 1.5673 1.5313 1.5037 -0.7769 3.2467 -0.7608 -0.7552 -0.7496 -0.7380 -0.7320 2.9498 2.8673 2.7855 2.5773 2.4691 -0.6507 1.7452 -0.6350 -0.6185 -0.6013 -0.5831 -0.4226 -0.3612 1.7301 1.7211 1.7152 1.7094 1.6051 1.5600 5 82 C [Cu(MPAMT)Cl.HO] b I -0.7608 3.0030 -0.7580 -0.7562 -0.7512 -0.7496 2.8328 2.6109 2.2321 2.1052 -0.7440 1.9685 -0.6801 -0.6657 -0.6507 -0.6350 -0.6185 -0.6013 -0.5831 -0.5640 1.7094 1.6977 1.6863 1.6806 1.6750 1.6694 1.6638 1.6482 2 II 83 Table XIV Data characteristics, obtained TG analysis :temperature activation energies and frequency factors of decomposition process. O Complex [Co(MMAMT)Cl.2H 0] T / c 40 T / °C 10' 210 T /°C max 640 Process I II [Ni(MMAMT)Cl.2H20] 35 125 580 I II [Cu(MMAMT)Cl.H 0] 40 220 688 I II [Co(MPAMT)Cl,2H20] 98 40 850 I II [Ni(MPAMT)Cl.2H20] 50 220 580 I II [Cu(MPAMT)Cl.HO] 70 285 720 I II 84 Ea/ In A/ •1 . -1 kJ mol mm 0.95 4.34 12.44 9.17 1.66 5.14 12.12 9.25 1.53 5.02 14.67 9.90 2.17 5.60 27.52 13.02 1.14 4.56 30.63 5.91 0.22 2.60 44.67 16.94 Table XV Thermogravimetric parameters for the thermaldegradation of the complexes Complex [Co(MMAMT)Cl.2H 0] [Ni(MMAMT)Cl.2H 0] [Cu(MMAMT)Cl.HO] [Co(MPAMT)Cl.2H20] [Ni(MPAMT)Cl.2H20] [Cu(MPAMT)Cl.HO] Process # aG kJ mol ^ # AH J K ^ mol ^ # AS kJ mol 1 I -2.26 -150.90 56.13 II 7.18 -126.82 87.46 I -1.35 -149.41 50.67 II 7.26 -126.77 81.42 I -1.48 -149.69 52.85 II 9.72 -122.89 82.96 I -0.76 -147.99 51.47 II 22.36 -100.63 84.85 I -1.75 -151.57 51.47 II 25.45 -87.73 80.11 I -3.50 -152.25 64.70 II 39.67 -73.85 84.06 85 stage. This may be attributed to the structural rigidity of the ligand, MMAMT/MPAMT, requires more as energy for compared its any compositional change. with H^O and rearrangement before Further, it Cl, which undergoing is generally observed that step wise formation constants decrease with an increase in the number of ligands attached to the metal ion 121 . During the decomposition reactions a reverse effect may occur. Hence the rate of removal of the remaining ligands will be smaller after the expulsion of one or two ligands 122 The values of the entropy for all degradation steps of all the complexes are negative. are negative for the first The enthalpies step and positive of activation for the second. However, the negative values of the entropies of activation are compensated by the values of the enthalpies of activation leading to almost the same values (50.67-87.46 k J mol ) 123 for the free energies of activation. kinetic studies of lanthanide(III) complexes of MPSMT For different stages of the thermal degradation process of the lanthanide(III) complexes were made (Table XVI) and are shown in Figs. 20, 21 and 22. Fig. 20 is for first step of the degradation, Fig. 21 is for second step of the degradation and Fig. 22 for the third step. 86 In order to determine the thermal 248 244 250 .1 256 U2 2.98 -3 -1 TX10 K Fig. 20 Plots of ln(ln 1/y) vs. 1/T for the first degradation process of (A) [Nd(MPSMT) NO 12H O; (B) [Dy(MPSMT) NO 12H O 2 o 2 2 O 2 (C) [La(MPSMT) NO 1H O / J Z Fig. 21 Plots of ln(ln 1/y) vs. 1/T for the second degradation process of (A) [Dy(MPSMT) NO ]2H O; (B) [La(MPSMT) NO ]H O; 2 3 2 2 3 2 (C) [Nd<MPSMT> NO 12H O 2 O Z 0.06 o 9 ft M* a P Q . t o to 1 p c t n 2 O CO a a rt M. 9* C D D * ft * 1 t o a t o 0 < a £ o H a CO cu a 2 wT> « CM CM H a w 0 . wa>1 A O m m < o o 0 u a CO v N— 9 a o o ft w Uh to to tnflnSY) - stability such as trend T , o T of 10 , lanthanide(III) T max , complexes activation energy the (Ea) parameters and frequency ^ J factor (In A), were evaluated and are given in Table XVII. The thermodynamic parameters, (AH a ) , enthalpy entropy # (ASff) and free energy (AG ) of activation, were calculated and the values are given in Table XVIII. The As indicates possible a # values have been found ordered more through the activated chemisorption to be negative, which state of oxygen which might and be other decomposition products. The energy of activation values for the second stage of decomposition were found to be higher than that for the first decomposition of stage second stage. But finally, This may ligand. NO^ be indicates stage is lower that the than that rate of of first third stage decomposition becoming faster. attributed to In the first stage, might XVII. be which the structural rigidity of the the simple molecules like H20 and eliminated which require minimum energy (Table In the second stage, the structure of the ligand (MPSMT) is complicated which requires more energy for its rearrangement before undergoing any compositional change. However, energy of activation of last stage is much lower than expected because in this another molecule of MPSMT is removed. This may be 87 due to Table XVI complexes Kinetics of decomposition studies on lanthanide(III) of 3-N-Methylpipiridino-4-salicylideneamino-5- mercpto-1,2,4-triazole Complex code Complex Stage [La(MPSMT) NO ]H 0 I II B 4 [Nd(MPSMT) 2NC>3] 2H20 I II III 88 In(In l/y) 1/TxlO3 -0.7380 2.8380 -0.7356 -0.7320 -0.7005 -0.6938 -0.6972 -0.6729 -0.2475 -0.2253 -0.1511 2.6953 2.4813 1.9305 1.9120 1.9013 1.8902 1.7331 1.7182 1.6891 -0.6185 2.9154 -0.6143 -0.6100 -0.5968 -0.5923 -0.5878 -0.5785 2.8735 2.7932 2.5510 2.4875 2.3696 2.1643 -0.5541 2.0080 -0.5439 -0.4081 -0.3931 -0.3774 1.9685 1.8348 1.8248 1.8083 -0.1772 1.6528 -0.1511 -0.1234 -0.0940 -0.0627 1.6313 1.6051 1.5797 1.5455 -0.0462 1.5267 Table XVII Data obtained TG analysis : temperature characteristics, activation energies and frequency factors of decomposition process. Complex T / C [La(MPSMT)2N03]H20 80 T /°C T /°C 10 max 235 540 Ea/ In A/ , -1 . -1 kJ mol mm Process 0.33 3.06 39.88 16.54 1.32 4.86 20.29 11.86 III 1.91 5.68 I 0.76 4.19 35.72 15.72 3.75 23.13 I II [Nd(MPSMT) NO ]2H 0 55 185 630 I II [Dy(MPSMT)2N03]2H20 40 130 690 II III 89 Table XVIII Thermogravimetric parameters for the thermal degradation of the complexes Complex Process 4a*-i kJ mol [La(MPSMT)2n°3]H2° [Nd(MPSMT)2N03]2H20 mol I -2.67 .-153.86 27.52 II 35.62 -71.35 107.74 I -1.83 -151.72 45.43 II 31.47 -78.85 52.67 3.38 -157.81 105.17 I -2.18 -148.00 60.29 II 15.75 -108.81 43.54 III -3.26 -131.90 78.90 III [Dy (MPSMT) 2NC>3] 2H20 < J K AG# kJ mol ^ 90 catalytic activity of metal complexes in the oxidation of the ligand and other decomposition products in the third stage. The catalytic activity of lanthanum(III) complex (Table XVI) is more pronouced because the decomposition completes only in two stages. X-ray (powder) diffraction studies The X-ray [Cu(MPAMT).Cl(H^O)] Phillips (powder) were diffraction recorded diffractometer pattern (in for cellulose using CuKa radiation complex phase) on (A. = 1.5418 A°) O with angular range of 10-70 to know the internal structure of the complexes. The diffractogram is reproduced in Fig. 23. The 20 values for prominent peaks have been indexed and their Q values have been compared with the Q values calculated XIX) . The tetragonal observed values system with a = are in ° 27.735A , c good = (Table agreement 11.658A 3 and with cell volume = 8967.68A . The diffractogram of [Dy(MPSMT) NO ].2H 0 is recorded M 4W o with CuKa X-ray tube in the range of 10-70 . The 20 and 'd' spacings for the prominent peaks are listed in Table XX and are indexed by trial and presented in Fig. 24. error method. The diffractogram is The observed values for the complex are 91 T O Lf> 30 D if f r a c tio n a n g le ( 2 © ) ^^ 20 F iR . 2 3 D if f r a c to R r a m o f lC u(liP A M T )C l(H 2 0 ) 40 — iU_ ] 10 F ig . 24 D if f r a c to g r a m o f ID y(M PSllT) D if f r a c t io n a n g le ( 2 6 ) « «5 4 NO 12H O Table XIX Peak X-ray (powder) 20 d K obs . diffraction data of d , cal . [Cu(MPAMT)Cl.H^O] 0 K obs . Qcal. r(Q) Relative h k 1 Intensity No . in % 1 15.2 5.8288 5.829 0.0294 0.0294 0.0002 70 002 , 141 2 15.5 5.7170 5.704 0.0306 0.0307 0.0002 60 102 , 331 3 16.0 5.539 5.547 0.0326 0 .0325 0.0002 50 112 , 500 , 34 4 18.55 4.783 4.757 0 . 0437 0 .0442 0.0002 100 350 5 22.05 4.031 4.018 0 .0615 0.0619 0 . 0003 75 502 6 2 3.75 3.746 3 .742 0 . 0713 0.0714 0 . 0003 85 2 0 3, 4 4 2, 70 7 26.35 3.382 3.390 0.0874 0.0870 0.0003 55 403 , 4 13, 36 8 26.75 3.332 3.340 0 . 0900 0 . 0896 0 .0003 70 3 3 3. 801 9 31.35 2.853 2.852 0 . 122 8 0 . 1229 0.0004 50 224 , 6 6 2, E8 10 31.60 2.831 2.832 0.1247 0 . 1247 0-0004 75 2 14, 363 , 38 11 32 . 60 2 . 746 2.746 0.1326 0.1326 0 .0004 65 482 , 491, 10 12 38.90 2.315 2.315 0.1866 0 . 1866 0 . 0005 55 105 , 115, 46 13 43.85 2.065 2.064 0.2346 0 . 2347 0.0005 48 2 65 , 5 84, 39 14 49.75 1 .8327 1.834 0 .2977 0 . 2974 0 . 0006 45 506 , 346 , 51 For Tetragonal system a = 2 7.7 3 5 A ’ C * 11.658A' Cell volume = 8967.68A' 92 Table XX Peak X-ray 20 (powder) d . obs . diffraction data of dcal . [DytMPSMT)^ NO^] 311^0 Qcal . Q . obs . c Tq ) No . Relative h k 1 Intensity in % 1 15.25 5.810 5.813 0.0296 0.0296 0.0002 75 005 , 2 16.05 5 . 522 5 .573 0 .0328 0.0322 0 . 0002 21 113 3 17.80 4 . 982 8 4 . 982 0.0403 0 . 0403 0.0002 25 105 , 114 4 20.60 4.3115 4.325 0 . 0538 0 . 053 5 0.0003 15 106 , 203, 5 2 1.40 4.152 4.152 0.0580 0.0580 0.0003 40 007 , 212 6 22.60 3.934 3.948 0 . 0646 0 . 0642 0.0003 29 116 , 213 7 2 6.80 3.3265 3.327 0 . 0904 0 . 0 903 0.0003 100 8 30.45 2.9355 2.946 0 . 1160 0.1152 0.0004 20 22 5 , 9 41.85 2.1585 2.158 0 . 2146 0 .2147 0.0005 19 3 0 10 , 10 46.00 1.973 1 . 974 0.2569 0 . 2 566 0.0005 18 246 , Fcr Tetragonal system a = 9.667A c = 29.064A Cell volume = 2716.05A* 93 104 21 222 304 238 , 4 18 o in good agreement with a tetragonal system with a = 9.667A , c = 29.064A o ° and cell volume = 2716.05A . Based on the above studies, the following structures could be proposed for the complexes under study, i) Structures of cobalt(II), nickel(II) and copper(II) complexes of MMAMT and MPAMT N---N -N NN AA As i , /C' H2N—►M fcXOH2 H2O/tN'0H2 N---N N---N f1 h2n sA J I s t Cw*— H2N M N---N r H2n—►Cu M = Co, Ni ii) Structures of cobalt(II), nickel(II) and copper(II) complexes of MMSMT and MPSMT N-N M = Co, Ni 94 iii) Structures of Lanthanide(III) complexes of MPSMT Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, Y n = 1-3 SUMMARY AND CONCLUSION Twelve copper(II) new with synthesised complexes MMAMT, and MPAMT, characterised analysis, molar conductance, ESR, thermal and stoichiometry complexes with of studies. for the cobalt(II), MMSMT on and the MPSMT basis magnetic moment, The cobalt(II), magnetic analytical suggest that cobalt(II), nickel(II) and have of and suggest been IR, 1:1 copper(II) electronic and copper(II) and elemental electronic, data nickel(II) moment nickel(II) spectra with MMAMT, MPAMT complexes are polymeric with octahedral geometry. The IR spectral studies suggest that MMAMT and MPAMT act as monobasic bidentate ligand utilising the amino nitrogen atom and mercapto sulphur atom for bonding. 95 The triazole ring nitrogen acts as a coordinating site product. The [Cu(MPAMT).Cl leading X-ray (H^O) ] to the formation (powder) complex of a diffraction is in good polymeric pattern agreement of with ° tetragonal system with a = 27.735A , c = 11.658A and cell O volume = 8967.68A . Based cobalt(II), MPSMT, on magnetic nickel(II) and electronic and copper(II) spectral complexes studies of MMSMT and octahedral geometry is suggested for the cobalt(II) nickel(II) complexes complexes. The MPSMT as act IR and spectral dibasic oxygen atom for bonding. oxobridge studies tridentate azomethine nitrogen atom, of the copper(II) tetrahedral mercapto geometry for suggest that ligands sulphur of and copper(II) MMSMT utilising and the atom and phenolic The low magnetic moments and IR data complexes suggest that these complexes have structure; the electronic spectra imply that the copper(II) has coordination number four in these complexes. Fourteen new complexes of lanthanide(III) nitrates with MPSMT have been synthesised and characterised on the basis of elemental analysis, electronic, IR, Analytical, thermal general formula NMR, molar conductance, thermal and [Ln(MPSMT) 96 molar and X-ray magnetic moment, diffraction studies. conductance data suggest the NO ],nH 0 for these complexes. The observed slight magnetic of lanthanide(III) deviation from the Hunds values values. as complexes well show as Van Vleck This indicates little participation of 4f electrons in bond formation. MPSMT moments acts a The IR and NMR spectral studies suggest that as monobasic bidentate ligand utilising the azomethine nitrogen atom and phenolic oxygen atom for bonding. Sulphur atom has lanthanide (III) not taken part ion. The IR in the spectral coordination and molar to the conductance data suggest that nitrate ion is coordinated bidentately to the lanthanide ion. [Dy (MPSMT) The X-ray N03].2H20 (powder) complex is diffraction in good pattern agreement ® tetragonal system with a = 9.667A , of with 0 c = 29.064A and cell O volume = 2716.05A . PUBLICATIONS 1) The part of this chapter has been published under the title "Thermal and spectral studies of 3-N-methylmorpholino-4amino-5-mercapto-l,2,4-triazole and 3-N-methylpiperidino-4amino-5-mercapto-l,2,4-triazole complexes of cobalt(II), nickel(II) and copper(II)" in the journal Thermochimica Acta 4545, 1-7 1998. 97 2) The part of this chapter has been sent for publication under the title "Synthetic, spectral, thermal and biological studies of 3-N-methylmorpholino-4-salicylideneamino-5mercapto-1,2,4-triazole and 3-N-methylpiperidino-4salicylideneamino-5-mercapto-l,2,4-triazole complexes of cobalt(II), nickel(II) and copper(II)" in the journal "Transition metal Chemistry" 1998. 3) The part of this chapter has been published under the title "synthetic, spectral, thermal and biological studies of lanthanide(III) complexes with a Schiff base derived from 3-N-methylpiperidino-4-salicylideneamino-5-mercapto-l,2,4triazole" in the journal "Synthesis Reactivity Inorganic and Metal-Organic Chemistry" 29, 98 (3) 1999.