Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Persistent carbene wikipedia , lookup
Jahn–Teller effect wikipedia , lookup
Metalloprotein wikipedia , lookup
Hydroformylation wikipedia , lookup
Metal carbonyl wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Spin crossover wikipedia , lookup
Indian Journal of Chemistry Vol. 47A, April 2008, pp. 560-564 Synthesis, structural characterization of new macrocyclic Schiff base derived from 1,6-bis(2-formylphenyl)hexane and 2,6-diaminopyridine and its metal complexes Salih İlhana,*, Hamdi Temelb, Murat Sunkurc & İbrahim Teğina a Siirt University, Faculty of Art and Sciences, Chemistry Department, Siirt, Turkey b Dicle University, Faculty of Education, Chemistry Department, 21280 Diyarbakır, Turkey c Batman University, Faculty of Technical Education, Batman, Turkey Email: [email protected]; [email protected] Received 25 January 2008; revised 17 March 2008 A macrocyclic ligand has been synthesized by reaction of 2,6-diaminopyridine and 1,6-bis(2-formylphenyl)hexane. Its complexes with Cu(II), Ni(II), Pb(II), Zn(II), Cd(II) and La(III) have been synthesized by the reaction of ligand and Cu(ClO4)2.6H2O, Ni(ClO4)2.6H2O, Pb(ClO4)2.6H2O, Zn(ClO4)2.6H2O, Cd(ClO4)2.6H2O and La(ClO4)3.6H2O, respectively. The ligand and its metal complexes have been characterized. All complexes are diamagnetic while the Cu(II) complex is binuclear. IPC Code: Int. Cl.8 C07F1/08; C07F3/06; C07F3/08; C07F5/00; C07F7/00; C07F15/04 The coordination chemistry of macrocyclic ligands is a fascinating area in inorganic chemistry1. Transition metal macrocyclic complexes have received much attention as active part of metalloenzymes as biomimic model compounds due to their resemblance with natural proteins like hemerythrin and enzymes2,3. Schiff base macrocycles have been of great importance in macrocyclic chemistry4. There is a continued interest to synthesize macrocyclic complexes5-7 because of their potential applications in fundamental and applied sciences7-9 and importance in the area of coordination chemistry10,11. The development of the field of bioinorganic chemistry has been another important factor in spurring the growth in interest in macrocyclic compounds12. We report herein the synthesis of a new dialdehyde 1,6-bis(2-formylphenyl)hexane derived from 1,6-dibromohexane with salicylaldehyde and K2CO3. The new macrocyclic Schiff base has been synthesized by reaction of 2,6-diaminopyridine and 1,6-bis- (2-formylphenyl)hexane. Its Cu(II), Ni(II), Pb(II), Zn(II), Cd(II) and La(III) complexes have been synthesized by template effect by reaction of the ligand and Cu(ClO4)2.6H2O, Ni(ClO4)2.6H2O, . . Pb(ClO4)2 6H2O, Zn(ClO4)2 6H2O, Cd(ClO4)2.6H2O and La(ClO4)3.6H2O, respectively. Spectral and magnetic properties of the new compounds have also been studied in detail. Experimental Elemental analysis was carried out on a LECO CHNS (model 932) elemental analyzer. 1H NMR and 13 C NMR spectra were recorded using a Bruker Avance DPX-400 NMR spectrometer. IR spectra were recorded on a Midac 1700 FTIR spectrometer on KBr discs in the range 4000-400 cm-1. Electronic spectral studies were conducted on a Shimadzu (model 160) UV-vis spectrophotometer in the range 200-800 nm, using 10-3 M solution of the complex in DMSO. Molar conductivity was measured with a WTW LF (model 330) conductivitymeter, using 10-3 M solution of the complex in DMSO. Electrospray ionization mass spectrometric analyses (ESI–MS) were obtained on the Agilent 1100 MSD spectrometer. 1,6-Bis(2-formylphenyl)hexane was prepared derived from 1,6-dibromohexane with salicyaldehyde and K2CO3 as reported in literature13. All the other chemicals and solvents were of analytical grade and used as received. Synthesis of 1,6-bis(2-formylphenyl)hexane To a stirred solution of salicylaldehyde (24.4 g, 0 .2 mol) and K2CO3 (13.8 g, 0, 1 mol) in DMF(100 mL), was added dropwise 1,6-dibromohexane (24.4 g 0.1 mol) in DMF (40 mL). The reaction was continued for 4 h at 150-155 °C and then for 4 h at room temperature (Scheme 1). Then, 200 mL distilled water was added and the mixture kept in a refrigerator. After 1 h, the precipitate was filtered and washed with 500 mL water. It was dried in air and recrystalized from EtOH and filtered under vacuum. Yield: 49 g (75%), M. pt: 75-77 °C, Color: white. Anal.: Calcd for C20H22O4: C, 73.60, H, 6.79. Found: C, 73.75, H, 6.73. 13 C NMR (DMSO-d6, δ ppm): CH2CH2CH2: 25.64, CH2CH2O: 28.87, CH2CH2O: 68.71, HC=O: 189.59, Aromatic: 113.99, 120.99, 124.71, 128.03, 136.89, 161.55. 1H NMR (DMSO-d6, δ ppm): 1.54 (t, 4H, J = 7.4 Hz, CH2CH2CH2:), 1.81 (p, 4H, J = 6.2 Hz, CH2CH2O), 4.14 (t, 4H, J = 6.4 Hz, CH2CH2O), NOTES 7.04-7.69 (m, 8H, Ar-H), 10.39 (s, 2H, HC=N). Selected IR data (KBr, ν cm-1): 3070, 3035 ν(Ar-CH), 2951, 2854 ν(Alf.-CH), 1681 ν(C=O), 1489, 1458 ν(Ar-C=C), 1284, 1246 ν(Ar-O), 1192, 1046 ν(R-O), 760 ν(substituted benzene). Synthesis of the macrocyclic Schiff base (L) The macrocyclic ligand (L) was prepared by the dropwise addition of a solution of the 2,6-diaminopyridine (0.22 g, 2 mmol) in methanol (40 mL) to a stirred solution of 1,6-bis(2formylphenyl)hexane (0.65 g, 2 mmol) in methanol (60 mL). After the addition was completed, stirring was continued for 2 h. A yellow colored precipitate (Scheme 2) was filtered and washed with methanol. Yield: 0.44 g (55.14%). Color: yellow. Anal.: Calc. for C25H25N3O2.H2O: C, 75.16, H, 6.31, N, 10.52. Found: C, 75.38, H, 6.41, N, 10.44. 13C NMR (DMSO-d6, δ ppm): CH2CH2CH2: 22.59, CH2CH2O: 28.66, CH2CH2O: 68.65, HC=N: 189.60, Aromatic: 112.70, 113.95, 120.99, 124.69, 128.06, 136.90, 157.55, 159.71, 161.53. 1H NMR (DMSO-d6, δ ppm): 1.52 (4H, CH2CH2CH2), 1.81 (4H, CH2CH2O), 4.16 (4H, CH2CH2O), 6.99-7.69 (m, 11H, Ar-H), 10.41 (s, 2H, HC=N). Selected IR data (KBr, ν cm-1): 3379 (H2O), 3062, 3035 ν(Ar-CH), 2935, 2862 ν(Alf.-CH), 1689 ν(C=N), 1598 (C=N(pyridine)), 1489, 1454 ν(Ar-C=C), 1288, 1238 ν(Ar-O), 1161, 1045 ν(R-O), 752 ν(substituted benzene). UV-vis (λmax, nm) (DMSO)): 267, 323, 378. Mass spectra (m/z): 399 [L]+. Synthesis of the complexes To a stirred solution of ligand in chloroform (60 mL), was added dropwise M(ClO4)n.6H2O (2 mmol, if M = Cu, 4 mmol) in methanol (40 mL). After the addition was completed, the stirring was continued for 2 h. 561 Then, the precipitate was filtered and washed with CHCl3, and then methanol, and dried in air (Fig. 1). Characterization of [Cu2(L)(ClO4)2][ClO4]2.H2O Color: brown. Yield: 0.43 g (22.8%). Anal.: Calc. for Cu2C25H25N3Cl4O18.H2O: C, 31.85, H, 2.87, N, 4.46. Found: C, 32.04, H, 3.01, N, 4.37. 1H NMR (DMSO-d6, δ ppm): 1.55 (CH2CH2CH2), 1.83 (CH2CH2O), 4.15 (CH2CH2O), 7.06-7.67 (Ar-H), 10.39 (HC=N). Selected IR data (KBr, ν cm-1): 3348 (H2O), 3066 ν(Ar-CH), 2931, 2862 ν(Alf.-CH), 1651 ν(C=N), 1598 (C=N(pyridine)), 1489, 1454 ν(Ar-C=C), 1242 ν(Ar-O), 1103 ν(R-O), 756 ν(substituted benzene), 1103, 621 ν(ClO4-). ΛM = 197 Ω-1.mol-1.cm2. UV-vis (λmax, nm) (DMSO): 271, 325, 377. Mass spectra (m/z): 824 [[Cu2(L)(ClO4)2][ClO4]2-H]+. Characterization of [Ni(L)(ClO4)2].2H2O Color: yellow. Yield: 0.16 g (11.6%). Anal.: Calc. for NiC25H25N3Cl2O10.2H2O: C, 43.35, H, 4.19, N, 6.07. Found: C, 43.46, H, 4.31, N, 5.96. 1H NMR (DMSO-d6, δ ppm): 1.56 (CH2CH2CH2), 1.92 (CH2CH2O), 4.17 (CH2CH2O), 6.93-7.70 (Ar-H), 10.40 (HC=N). Selected IR data (KBr, ν cm-1): 3383 (H2O), 3069 ν(Ar-CH), 2935, 2866 ν(Alf.-CH), 1646 ν(C=N), 1598 (C=N(pyridine)), 1489, 1454 ν(Ar-C=C), 1292, 1242 ν(Ar-O), 1091, 1046 ν(R-O), 752 ν(Substituted benzene), 1113, 629 ν(ClO4-). ΛM = 25 Ω-1.mol-1.cm2. UV-vis (λmax, nm) (in DMSO): 274, 326, 375. Mass spectra (m/z): 658 [Ni(L)(ClO4)2+2H]+. Characterization of [Pb(L)(ClO4)][ClO4].2H2O Color: yellow. Yield: 0.48 g (28.5%). Anal.: Calc. for PbC25H25N3Cl2O10.2H2O: C, 35.67, H, 3.45, N, 4.94. Found: C, 35.82, H, 3.79, N, 4.99. 1H NMR INDIAN J CHEM, SEC A, APRIL 2008 562 Fig. 1 – Proposed structure of the complexes (X=ClO4). could not be taken because of the low solubility Selected IR data (KBr, ν cm-1): 3348 (H2O), 3070 ν(Ar-CH), 2931, 2858 ν(Alf.-CH), 1651 ν(C=N), 1598 (C=N(pyridine)), 1489, 1454 ν(Ar-C=C), 1288, 1238 ν(Ar-O), 1161, 1099 ν(R-O), 751 ν(Substituted benzene), 1108, 621 ν(ClO4-). ΛM = 88 Ω-1.mol-1.cm2. UV-vis (λmax, nm) (in DMSO): 274, 326, 377. Mass spectra (m/z): 594 [Pb(L)(ClO4)]-H]+. Characterization of [Cd(L)][ClO4]2.3H2O Color: yellow. Yield: 0.63 g (44.7%). Anal.: Calc. for CdC25H25N3Cl2O10.3H2O: C, 42.61, H, 4.40, N, 5.97. Found: C, 42.77, H, 4.67, N, 6.03. 1H NMR (DMSO-d6, δ ppm): 1.68 (CH2CH2CH2), 1.92 (CH2CH2O), 4.18 (CH2CH2O), 7.06-7.69 (Ar-H), 10.39 (HC=N). Selected IR data (KBr, ν cm-1): 3371 (H2O), 3070 ν(Ar-CH), 2931, 2858 ν(Alf.-CH), 1647 ν(C=N), 1598 (C=N(pyridine)), 1489, 1454 ν(Ar-C=C), 1288 1238 ν(Ar-O), 1161, 1099 ν(R-O), 756 ν(Substituted benzene), 1106, 621 ν(ClO4-). ΛM = 169 Ω-1.mol-1.cm2. UV-vis (λmax, nm) (DMSO (1:1)): 273, 376. Mass spectra: 668 [[Cd(L)](ClO4)2]+. Characterization of [La(L)(ClO4)3(H2O)].H2O Color: yellow. Yield: 0.55 g (31.6%). Anal.: Calc. for LaC25H27N3Cl3O15.H2O: C, 34.44, H, 3.33, N, 4.82. Found: C, 34.56, H, 3.61, N, 4.89. 1H NMR (DMSOd6, δ ppm): 1.55 (CH2CH2CH2), 1.91 (CH2CH2O), 4.18 (CH2CH2O), 7.07-7.67 (Ar-H), 10.39 (HC=N). Selected IR data (KBr, ν cm-1): 3363 (H2O), 3070 ν(Ar-CH), 2931, 2862 ν(Alf.-CH), 1651 ν(C=N), 1598 (C=N(pyridine)), 1489, 1454 ν(Ar-C=C), 1292, 1242 ν(Ar-O), 1103, 1049 ν(R-O), 756 ν(Substituted benzene), 1106, 625 ν(ClO4-). ΛM = 34 Ω-1.mol-1.cm2. UV-vis (λmax, nm) (in DMSO): 273, 323, 377. Mass spectra (m/z): 752 [La(L)(ClO4)2(H2O)-H]+. NOTES Characterization of [Zn(L)(ClO4)2].2H2O Color: yellow. Yield: 0.18 g (12.9%). Anal.: Calc. for ZnC25H25N3Cl2O10.2H2O: C, 42.92 H, 4.15, N, 6. 10. Found: C, 43.09, H, 4.21, N, 6.04. 1H NMR (DMSO-d6, δ ppm): 1.56 (CH2CH2CH2), 1.90 (CH2CH2O), 4.16 (CH2CH2O), 6.06-7.71 (Ar-H), 10.40 (HC=N). Selected IR data (KBr, ν cm-1): 3363 (H2O), 3074 ν(Ar-CH), 2935, 2862 ν(Alf.-CH), 1647 ν(C=N), 1598 (C=N(pyridine)), 1489, 1454 ν(Ar-C=C), 1292, 1242 ν(Ar-O), 1049 ν(R-O), 756 ν(Substituted benzene), 1107, 625 ν(ClO4-). ΛM = 24 Ω-1.mol-1.cm2. UV-vis (λmax, nm) (in DMSO): 276, 323, 374. Mass spectra: 664 [Zn(L)(ClO4)2+H]+. Result and discussion The ligand and complexes (Schemes 1 and 2) have been synthesized and characterized by elemental analysis, IR, 1H and 13C-NMR data, electronic spectra, magnetic susceptibility measurements, molar conductivity measurements and mass spectra. The IR spectra of the ligand (L) show a ν(C=N) peak at 1689 cm-1 and the absence of a ν(C=O) peak at around 1700 cm-1 is indicative of Schiff’s base condensation. The IR spectra of all complexes shows ν(C=N) bands at 1646-1651 cm-1 and it is found that the ν(C=N) bands in the complexes are shifted by about 43-38 cm-1 to lower energy regions compared to that in the free ligand (L). This phenomenon appears to be due to the coordination of azomethine nitrogen to the metal ion14. Also, a weak ν(H2O) band of free ligand at about 3380 cm-1 is observed because of hydrated water molecule. The IR spectra of the complexes are characterized by the appearance of a broad band in the region at 3328- 3383 cm-1 due to H2O groups21. Also, infrared spectra of the metal complexes exhibit an intense band at approximately 1110 cm-1 along with a weak band at ca. 620 cm-1 which is assigned to ν(Cl-O) of perchlorate anions16. The IR spectra of the complexes clearly demonstrate that the COC and CCO stretching vibrations are altered compared to ligands due to conformational changes. The fact that the C-O-C absorptions of the complexes are shifted to lower wave numbers compared to that of the ligand also confirms the complex formation17. The spectra of all the complexes are dominated by bands between 2955-2828 cm-1 due to ν(Alph.-CH) groups and a strong band appearing in the 1598cm-1 region is assigned to ν(C=N)pyridine mode. The ν(C=N)pyridine did not change in the complexes, indicating that azomethine group in the pyridine does not bind the metal ions18. 563 1 H NMR and 13C NMR of the 1,6-bis(2formylphenyl)hexane, ligand and 1H NMR of the complexes in DMSO-d6 solution show that they are NMR active. The 1H NMR spectrum of the 1,6-bis(2formylphenyl)hexane showed a singlet at 10.39 ppm due to the aldehyde protons, multiplet in the range approximately 7.03-7.70 ppm due to the aromatic protons, at 1.66 ppm due to CH2CH2CH2 protons, at 1.87 ppm due to CH2CH2O protons and at 4.16 ppm due to CH2CH2O protons (Scheme 1). 13C NMR spectrum of the aldehyde showed at 189.55 ppm due to the imine carbon, at 22.57 ppm due to CH2CH2CH2 carbon, 28.66 ppm due to CH2CH2O carbon, at 68.67 ppm due to CH2CH2O carbon, and at 133.98-161.53 ppm due to aromatic carbon. The 1H NMR spectrum of the ligand showed a singlet at 10.40 ppm due to the imine protons, multiplet in the range approximately 7.05-7.68 ppm due to the aromatic protons, at 1.66 ppm due to CH2CH2CH2 protons, at 1.86 ppm due to CH2CH2O protons and at 4.16 ppm due to CH2CH2O protons. 13C NMR spectrum of the ligand showed at 189.60 ppm due to the imine carbon, at 22.59 ppm due to CH2CH2CH2 carbon, at 28.66 ppm due to CH2CH2O carbon, at 68.65 ppm due to CH2CH2O carbon and at 112.68-161.53 ppm due to aromatic carbon. The 1H NMR spectra of the complexes exhibited almost the same values as that of the ligand. Although we expected a shift on the position of CH=N signal for the NMR spectra of the complexes, no significant shift could not be observed. But the CH=N signal is observed in low intensity compared to the ligand19. The electronic spectra of the ligand (L) in DMSO showed absorption bands at ca. 280, 320 and 370 nm. The bands are indicative of benzene and other chromophore moieties present in the ligand. The absorption bands of the complexes were shifted to longer wave numbers compared to that of ligand as expected. No d-d transitions for the complexes were observed probably due to low solubility of complexes. A moderately intensive band observed in the range of 320380 nm is due to π-π* transition, and the strong band observed in the range of 270-280 nm is due to n-π* for these complexes20. The observed room-temperature magnetic moment values for the binuclear Cu(II) and the other mononuclear complexes were found to be diamagnetic. The diamagnetic behaviour of the binuclear complex may be explained by a very strong anti-ferromagnetic interaction in the Cu-Cu pair18-20. The conductivity data in DMSO are reported in the range for 1:2 and 1:1 electrolytes. The complexes, 564 INDIAN J CHEM, SEC A, APRIL 2008 [Cu2(L)(ClO4)2][ClO4]2.2H2O, [Cd(L)][ClO4]2.3H2O and [Pb(L)(NO3)][NO3].2H2O have values of 197, 169 and 88 ohm-1 cm2 mol-1 indicating 1:2 and 1:1 electrolytes, respectively. The other complexes are nonelectrolytes18-20. The mass spectra of complexes with ligand play an important role in confirming the monomeric [1+1] (dicarbonyl and diamine) nature of the complexes. The MS peaks are attributable to the molecular ions: 399 [L]+, 824 [[Cu2(L)(ClO4)2][ClO4]2-H]+, 658 [Ni(L)(ClO4)2+2H]+, 594 [Pb(L)(ClO4)]-H]+, 668 [[Cd(L)](ClO4)2]+, 752 [La(L)(ClO4)2(H2O)-H]+, 664 [Zn(L)(ClO4)2+H]+ (refs 21-23) . The complexes have no clearly defined melting point and begin to decompose in the temperature range 250350 °C. The ligand is soluble in DMSO, DMF, CHCl3, CH2Cl2 and CH3CN but insoluble in H2O, EtOH and MeOH. The complexes are air stable, partly soluble in DMF, DMSO and insoluble CHCl3, CH2Cl2 and CH3CN and the crystals were unsuitable for singlecrystal X-ray structure determination. It is seen that the complex formation reaction between ligand and relatively large Cd(II) and Pb(II) metal ions result in the Cd(II) and Pb(II) complexes. The binding mode of the ligand for the Pb(II), Cd(II) and Cu(II) complexes are different than that of the other complexes. In the first case, the ligand behaves as a tetradentate ligand with the lone electron pairs of azomethine nitrogen atoms and the lone electron pairs of two oxygen in ether groups. In the second case, the ligand behaves as a bidentate ligand with the lone electron pairs of azomethine nitrogen atoms. The long distance binding process can be favored for very large Cd(II), Pb(II) metal ions but not other metal ions due to having smaller ion size than Pb(II) and Cd(II) metal ion. So, its coordination is satisfied with two or three ClO4- and one H2O for La(III) complex in the second case. Similar binding mode is known for Pb(II) and Cd(II) metal ions18-20, 24,25. Also, infrared spectra of the metal complexes exhibit an intense band at approximately 1110 cm-1 along with a weak band at ca. 620 cm-1 which have been assigned to the perchlorate complexes are due to ν(Cl-O) of perchlorate anions18-20. Also, the conductivity measurements of the Pb(II) and Cd(II) complexes in DMSO resulted in ΛM value 88 Ω-1mol-1cm2 and 169 Ω1 mol-1cm2, which indicate that they are 1:1 and 1:2 electrolyte type, respectively. These results clearly verify different binding mode of ligand in the case of the Cd(II) and Pb(II) metal ions. As expected, in the case of the relatively smaller (Ni(II) and Zn(II)) metal ions, the ligand behaves as a bidentate ligand with the lone electron pairs of azomethine nitrogen atoms and the inner coordination sphere is donated with ClO4ligands. The conductivity measurements showed that these complexes are nonelectrolyte. On the other hand, the diamagnetic behaviour of the binuclear complex can be explained by a very strong anti-ferromagnetic interaction in the Cu-Cu pair18-20,22. Structure of the binuclear complex is given in Scheme 2. Some Co(II), Ni(II), Ag(II), Zn(II) or Pb(II) complexes prepared with similar ligands are already known21. Suggested structure for Cu(II) complex is bipyramidal, for La(III) complex it is octahedral, for Pb(II) complex it is square pyramid, for Zn(II) and Cd(II) complexes it is tetrahedral and that for Ni(II) complex is square planar18-20,22. References 1 Khandar A A, Hosseini-Yazdi S A, Khatamian M, McArdle P & Zarei S A, Polyhedron, 26 (2007) 33. 2 Chandra S & Gupta L K, Spectrochim Acta Part A, 62 (2005) 307. 3 Radecka-Paryzek W, Patroniak V & Lisowski J, Coord Chem Rev, 249 (2005) 2156. 4 Temel H & İlhan, S, Spectrochim Acta Part A, 69 (2008) 896. 5 İlhan S, Temel H, Sünkür M & Teğin İ, Indian J Chem, 47A (2008) (in press). 6 İlhan S & Temel H, Indian J Chem, (submitted). 7 İlhan S, Indian J Chem, (submitted). 8 Tamburini S, Vigato V, Gatos M, Bertolo L & Casellato U, Inorg Chim Acta, 359 (2006) 183. 9 M E S Khalıl & Bashır K A, J Coord Chem, 55 (2002) 681. 10 İlhan S & Temel H, J Mol Struc, (2008) (in press). 11 İlhan S, Temel H & Kılıc A, J Coord Chem, 25 (2008) 1547. 12 Chandra S & Gupta L K, Spectrochim Acta Part A, 62 (2005) 307. 13 İlhan S, Temel H & Kılıc A, Chinese J Chem, 61 (2008) 277. 14 İlhan S, Temel H, Kılıç A & İ Yılmaz, Trans Met Chem, 32 (2007) 344. 15 Temel H, Ziyadanoğulları B, Alp H, Aydın I, Aydın F & İlhan S, Russ J Coord Chem, 32 (2006) 282. 16 İlhan S, Temel H, Kılıç A & Tas E, Trans Met Chem, 32 (2007) 1012. 17 Temel H, Hoşgören H & Boybay M, Spectroscopy Lett, 34 (2001) 1. 18 İlhan S, Temel H, Yılmaz İ & Şekerci M, Polyhedron, 26 (2007) 2795. 19 İlhan S, Temel H, Yılmaz İ & Şekerci M, J Org Met Chem, 692 (2007) 3855. 20 İlhan S, Temel H, Ziyadanoğulları R & Şekerci M, Trans Metal Chem, 32 (2007) 584. 21 Lodeiro C, Bastıda R, Bertolo E & Rodriguez A, Can J Chem, 82 (2004) 437. 22 İlhan S & Temel H, Trans Met Chem, 32 (2007) 1039. 23 Temel H, Alp H, İlhan S, Ziyadanoğulları B & Yilmaz İ, Mon Chem, 138 (2007) 1199. 24 Lodeiro C, Bastıda R, Bertolo E, Macias A & Rodriguez Trans Metal Chem, 23 (2003) 388. 25 Gao J, Xu X-Y, Ma W-X, Wang M-Y, Song H-B, Yang X-J, Lu L-D & Wang X, J Coord Chem, 57 (2004) 1553.