Photochemistry of some arene transition metal carbonyl and mixed carbonyl nitrosyl complexes isolated in frozen gas matrices at 12K

Taylor, David John (1981) Photochemistry of some arene transition metal carbonyl and mixed carbonyl nitrosyl complexes isolated in frozen gas matrices at 12K. University of Southampton, Doctoral Thesis.

Abstract

Photochemical processes have been studied for a variety of arena substituted transition metal carbonyl and carbonyl nitrosyl complexes isolated at low temperatures in frozon gas matrices. Infrared spectroscopic evidence is presented for the formation of a series of (arene)M(CO) complexes from their relative parent (arene)M(CO) complexes(arene=1)n-CnHn,2(CH )3C, 71n-CnHn+2' M= V, Cr, Mn, Fe, Cc) by photo ejection of CO in argon and meteane matrices. Also infrared spectroscopic evidence is presented for the formation of the corresponding complexes (arene)M(CO)2(N2) by the photoreplacement of CO by N2 in nitrogen matrices. A comparison of the series in argon, methane and nitrogen is given.Infrared spectroscopic evidence is given for the formation of (g5-C6H5)Co(CO)(N) from (t -C5H5)Co(CO)2 by the photoreplacement of CO by N2 in 5 nitrogen matrices. evidence is also presented for the dimerisation of (-q -C5H5)Co(CO)2 to form (7) -CSH6)Co(CO)2 in 4 nitrogen matrices. The photochemistry of (7I -CaH4)Fe(CO) and the related complex (q -C4H6)Fe(CO) has been studied in reactive CO matrices at 12K. It has been shown that their behaviour on irradiation is totally different with the formation of CO) 9 as the final irreversible photoproduct for (71 -C4H6)Fe(CO)3, and (TI -Cee4O)Fe(CO)3 for (7I -C~H4)Fe(CO). This is the first time that ring insertion of CO has been p served to occur in frozen gas matrices. The photochemistry of (-q -C and (-q -C H)Co(CO) has been studied in reactive CO matrices at 12k. It has been shown that increased CO coordination occurs on irradiation with the formation of (7q -CSHg)Co(CO) and (ij -C1H5)Co(CO)4 respectively. The infrared spectroscopic evidence presented includes CO labelling and CO-factored force field fitting for 7l -C5H5)Co(CO)2 and its photoproduct. In the case of (1I -C H5)Co(CO)4 a further photoreaction is observed with the formation of Co(Ca)el. Some ('q -C H)M(CO) (NO) complexes have been studied (M= Cr, V; n= 0-2) in argon, methane and nitrogen matrices. Infrared spectroscopic evidence is presented for CO loss in argon and methane and CO replacement in N2 matrices. CO labelling of Mn(CO) (NO) has allowed a CO-factored force field fitting of observed and calculated terminal stretching fundamentals for the molecule. The data presented confirms an X-ray analysis that the molecule possesses a trigonal bipyramidal structure with C2v symmetry.-A-.-M MON. Ph.D Thesis summary. Page 2. vibrational excitation in C10, i.e. V~T 3. this proposed reaction step is sufficinetly exothermic to make it worthy of inclusion in the kinetic scheme for this system. By assuming the reaction to be that of Cl + C10t (v~ > 31 it was found that its inclusion enhanced the accuracy of the theoretical description of the process. In this study the optimum rate coefficient for reaction (13 was estimated to be (1. 78 ± 1.45) x 10-10 cm 3 molecule 1 S-1 at 3000K.

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