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Russian Academy of Sciences A.N.Nesmeyanov Institute of Organoelement Compounds Laboratory of molecular spectroscopy 1 IR SPECTROSCOPIC AND THEORETICAL STUDY OF NEW PHOTOCHROMIC SYSTEMS BASED ON CYMANTRENE DERIVATIVES. B. V. LOKSHIN, M. G. EZERNITSKAYA, Yu. A. BORISOV, E. S. KELBYSHEVA. N. M. LOIM 2 hL M CO CO CO M L CO CO L = PR3, P(OR)3, SR2, olefins, acetylenes and other n- and pdonors 3 1 2 R1 R CHN-C-OtBu 2 R R CHN-C-OtBu crimson coloration O M CO CO CO M PPh3 CO CO hPPh3 colourless R1 = H R1 = CH3 R1 = CH3 yellow coloration R2 = H (1) R2 = H (2) R2 = CH3 (3) (4) (5) (6) R1 R2 CHN-C-OtBu M O h CO CO CO +CO in closed system Reverse dark reaction. O crimson coloration Colored during some hours at 10-250С Decomposition 4 Aim of the work: Study by infrared spectroscopy and quantum chemistry of the structure and stability of intermediates formed under irradiation of cymantrene derivatuves containing substituents, which are able to coordinate to the metal by its n-and π-donor centers (C=O or C=N group, pyridine or allyl). Experimental Photochemical reaction was carried out directly in the cell of the IR spectrometer, where the solution of tricarbonyl complex was irradiated with light of immersional mercury lamp Normag TQ 150. The monitoring the reaction was carried out by IR spectra. IR-fourier-spectroscopy - Magna-750 Nicolet instrument UV-VIS spectrocopy - SPECORD М-40 with digital registration. NMR-spectroscopy. Circular dichroism spectroscopy. DFT B3LYP/LanL2DZ calculations. The GAUSSIAN 03 program . 5 Initial carbamate С5H5Mn(СO)3CH2NHCOtBu Calculated structures Reaction product after UV-irradiation and СО removal. DFT B3LYP/LanL2DZ calculation with full optimization of geometry 6 UV-vis spectra of compound 3 (R1= CH3, R2= H) before and after 5 minute UV irradiation 3,0 Initial 2,5 After irradiation A 2,0 The spectrum after irradiation is not solventdependent (hexane, benzene, ethanol, THF). d-d-transition. 1,5 1,0 CH3 H CH-N-C-OtBu 0,5 0,0 300 400 500 600 O 700 M л, nm 0,25 CO CO CO (R)-isomer 3 (R)-isomer 6 (S)-isomer 3 (S)-isomer 6 (3) 0,20 0,15 CD spectra of (R) and (S) enantiomers 0,10 of compound 3 (R1= CH3, R2= H) 0,05 before and after UV-irradiation 0,00 350 -0,05 400 450 500 550 600 650 , mn -0,10 7 R1 R2 C-N-C-OtBu O Mn CO CO CO CO CO CH2-CH2-C-CH3 O Mn CO CO h h R1 CH N R2 Mn O C CO OtBu CO CH2 Mn CO CO CO O C CH2 CH3 + CH2 Mn C CH2 CO CO O CH3 Organometallic photochromic systems associated with removal and addition of the ligand and with intermediate stabilized by chelation between metal atom and the subsituent in Cp-ring. The process of removal and adddition of CO can be multiply repeated. DIRECT REACTION takes place with high rate upon irradiation with full light of UV-lamp or with the light in 300-400 nm region. The semiconvertion time T1/2 is about 3 min. REVERSE REACTION semiconvertion time T1/2 is 60-90 min. Upon irradiation with visible light 480-530 nm the reaction accelerates. T1/2 is about 10 min. 8 CYMANTRENES WITH BIFUNCTIONAL SUBSTITUENTS CH2 N Mn(CO)3 O Me C OtBu CH N CH Mn(CO)3 N D A O Me O C Me Me CH N CH2 Mn(CO)3 C N N C OtBu CH N CH2 Mn(CO)3 B N Wide range of compounds were also studied in order elucidate the nature 9 of the dicarbonyl intermediate stabilization. Irradiation in benzene solution of (СO)3MnCH2N(COOtBu)Py (A) results in removal of СО group and formation of dicarbonyl complex. The intensity of Amide I band is not changed and the pyridine ring stretch is 10 см-1 up shifted due to coordination with pyridine nitrogen atom. А A B S O R B A N C E 3.0 2.5 Absorbance 2.0 2000 1800 Wavenumbers (cm-1) 1600 1.5 430 1.0 b 324 0.5 a 0.0 200 300 400 500 600 700 800 900 1000 wavelength mn IR and UV-Vis spectra of complex A in benzene solution in the course of irradiation. 10 E0 = 9.1 kcal/mol CO calc.= 1862, 1917 cm-1 CO exp.= 1866, 1929 cm-1 CH2NC(=O)OtBu OÑ CH2NC(=O)OtBu CO Mn CO h CO N (А) OÑ Mn N CO 11 A B S O R B A N C E 1620 2000 1800 1600 1600 Wavenumbers (cm-1) IR spectra of (B) in benzene solution in the course of irradiation CH3 OÑ CHNC(=O)R CH2 Mn CO CO N CH3 h CHNC(=O)R CO OÑ CH2 Mn CO R = Otert.Bu (B), Me (C) N 12 A B S O R B A N B E Upon irradiation in benzene of (D) Mn(CO)3С5H4CH(CH3)N=CHPy the dicarbonyl chelate with coordination of imine nitrogen atom is formed. 2000 1900 Wavenumbers (cm-1) 2.5 A B S O R B A N C E Absorbance 2.0 1593 1648 1.5 462 1.0 326 0.5 0.0 200 1600 300 400 500 600 700 800 900 1000 wavelength nm Wavenumbers (cm-1) Me h CHN=CH OC N Mn CO CO CO CHMe OC Mn CO N (D) CH N 13 Initial complex D-cis =1683 cm-1 Coordination with pyridine nitrogen (СО)=1687 cm -1 Initial complex D- trans =1684 cm-1 E = 4.5 kcal/mol Trans-structure is more stable Coordination at imine nitrogen (СО)=1647 cm-1 Coordination at imine nitrogen is 3.1 kcal/mol more preferable. 14 1854 1903 0.5 1928 0.5 1966 Absorbance Absorbance Differential spectrum 0.0 0.0 2200 20502000 1900 Wavenumbers (cm-1) 2000 1800 Wavenumbers (cm-1) CH3 CH NCH2CH=CH2 OC Mn CO CO h -CO CH3 COOBut h +CO -CO CH3 CH OC Mn CO O=C NCH2CH=CH2 OBut OC Mn CO CH NCOOBut CH2 CH CH2 15 CH Mn(CO)3 O N CH2 CH Mn(CO)3 O 1 All N C N C OtertBu Mn(CO)3 Me Me 2 O R' CH N C R Mn(CO)3 All O 3 4 R= OtertBu, R'= Me 5 R= Me, R'= Me 6 R = OtertBu, R' = H 7 R= Me, R'= H 16 O h 1 CH - CO OC Mn CO N N CH CH2 10 1943 2025 O (CO)2Mn 9 A B S O R B A N C E CH + 1 1940 9 10 1878 In hexane and benzene solutions the products are formed kinetically independently in the ratio of 1:0.16, do not convert to one another and do not form a photochromic pair. In THF solution 10 isomerizes irreversibly to 9. 2025 1975 2100 1917 1900 2000 Wavenumbers (cm-1) 17 Structure 9 Pyridine complex Structure 10 π-allylic complex. DFT D3LYP/LanL2DZ calculation: 9 is 12.7 ккал/моль more stable than 10 18 Me h , - CO 3 C CH2CH=CH2 OC Mn O OC NMe C OCMe 3 C NMeCOOCM OC Mn CO CH CH2 14 13 3 A B S O R B A N C E Me 13 14 Upon irradiation of 3 in hexane and benzene, the kinetically preferable carbamate complex13 is initially formed. Then a mixture of carbamate 13 and olefinic 14 complexes is formed. In the dark reaction, 13 isomerizes to thermodynamically more stable 14. In the closed system the bands of tricarbonyl complex 3 appear. No isomerization of olefinic complex to carbamate upon irradiation was observed. 2000 1900 Wavenumbers (cm-1) 19 3 A B S O R B A N C E 13 14 2000 1800 1600 Wavenumbers (cm-1) In THF solution the result is the same but all the processes are faster. 20 2 , CO h O , CO CO h CH2 OC N Mn O h N CO OC Mn CO CH2 CH CH2 12 11 Upon irradiation of 2 in hexane the kinetically more favorable chelate 12 is initially formed ((СО) 1974 и 1916 см-1), then pyridine chelate 11 is formed ((СО) 1936 и 1870см-1). Upon consecutive irradiation the olefinic complex transforms to pyridine one. In the dark reaction 11 transforms slowly during 12-48 hours to 2 A B S O R B A N C E 1974 12 1916 11 more stable thermodynamically 12. 1936 1870 Hence 11 и 12 form the photochromic pair. 1900 2000 Wavenumbers (cm-1) 21 Me 4 h, - CO OC Mn O OC λmax = 516 нм CH NCH2CH=CH2 h C R 16 R = OCMe3 Me CH NCOR OC Mn CO λmax = 350 нм h, - CO 4 CH CH2 CH2 15 R = OCMe3 4 A B S O R B A N C E Complex 1972 1914 1939 16 1870 1700 15 2000 4 upon irradiation forms olefinic and carbamate 16 chelates in a ratio of 2:1. In the dark reaction, the carbamate complex transforms rapidly to olefinic, which after irradiation forms again the carbamate complex. Hence, dicarbonyl complexes 16 and 15 form the reversible photochromic system due to linkage isomerization in the bifunctional substituent. 1800 Wavenumbers (cm-1) 15 22 Initial compound 4. product 16 Mn coordination with carbamate group Substance E, kcal/mol Q, kcal/mol. Initial 4 - - Product 16 7.72 31.82 Product 0.00 26.10 15 СО 15 (Mn coordination with allylic group). *) E – relative energies of isomeric products Q corresponds to the processes 4 → 16 + СО и 4 → 15 + СО. 23 Me h, - CO 5 OC Mn O OC CH NCH2CH=CH2 h C R λmax = 509 nm Me CH NCOR OC Mn CO CH2 18 R = Me 1944 СОЕДИНЕНИЕ 5 (R=Me, R'=Me) 2027 CH CH2 λmax = 331 nm 17 R = Me 5 А 2 h, - CO 1 17 ОБЛУЧАЛИ 1 МИН А 0,15 Upon irradiarion 5 transforms mainly to 17, which isomerizes thermally to 18. Upon irradiation 18 again converts to17. Thus 17 and 18 form the reversible photochromic system 0,10 0,05 0,00 ТЕМНОВАЯ РЕАКЦИЯ 18 А 0,15 0,10 0,05 0,00 1872 А 1940 1917 1975 ОБЛУЧАЛИ 1 МИН ПОСЛЕ ТЕМНОВОЙ РЕАКЦИИ 0,4 0,2 24 2050 2000 1980 1960 1940 1920 Волновое число (см-1) 1900 1880 1860 1840 6,7 h, - CO CH2 NCOR OC Mn CO h CH CH2 CH2 CH 2 OC Mn O OC h, - CO 7 NCH2CH=CH2 C R 19 R = OCMe3, R' = H 20 R = Me, R' = H Upon irradiation of allylcarbamate Under experimental condinions, 19 В – coordination of Mn with carbamate group 21 R = Me, R' = H 6 in hexane, benzene or THF only olefinic chelate is a thermo- and photostable compound. 19 is formed. Stereoisomer 19S Stereoisomer 19R С - coordination of Mn with allylic group The structure С (R-stereoisomer) is more stable then B (ΔE = 7.09kcal/mol) . The energy difference between stereoisomers R and S is only 0.75 kcal/mol. 25 7 R=Me, R”=H 20 21 20 R=H is 6.08 kcal/mol more stable Photolysis of allylamide 7 in hexane gives only olefinic chelate 20. However both chelates 20 and 21 are the reaction products in benzene and 7 A B S O R B A N C E THF solution 1965 20 1903 21 1927 2000 1854 THF solutions. 21 is the major kinetic product in the first step of the reaction at temperatures below 10оС. Then it isomerizes to 20 for several minutes. The repeated irradiation of benzene solution of 20 (λmax 333 нм) leads to isomerization to chelate 21 with the appearance of red coloration (λmax 517 нм), which in dark process again transforms to 20. Hence, between 20 and 21 the reversible photochromic transition takes place with the high isomerization rate. 1900 Wavenumbers (cm-1) 26 CONCLUSIONS: 1. By the methods of IR, UV-Vis spectroscopy and quantum chemistry, the possibility of obtaining photochromic systems based on cymantrene derivatives containing mono- and bifunctional n-donor and p-donor substituents was studied. 2. When irradiated by a mercury lamp, the CO molecule is abstracted from tricarbonyl complexes and dicarbonyl chelates are formed, stabilized by intramolecular coordination of the manganese atom with a substituent in the Cp-ring. This changes the color of the solution. In a closed system the CO molecules released during irradiation adds again to the intermediate and the initial colour restores. The process can be carried out repeatedly. 3. In the case of cymantrenes with bifunctional substituents, photochromic systems were found, where the color change occurs due to linkage isomerization in the substituent. 4. The spectral data agree well with the results of quantum chemical calculations using DFT theory. 5. As a result of these studies, two- and three-component photochromic systems were found, where photochromic properties changes in dependence on CO abstraction and addition or linkage isomerization. 27