Photolytic and thermal properties of a new series of intramolecular bridged alkyl cobaloxime complexes

Abstract

The photolytic kinetic properties of a new series of intramolecular bridged alkyl cobaloxime complexes Br(O-C(3)H(6)-(dmgH))(dmgH))Co(III)(2), [H(2)O(O-C(3)H(6)-(dmg))(dmgH(2))]Co(III)[ClO(4)(3), ]Py(O-C(3)H(6)-(dmg))(dmgH(2))[Co(III)]ClO(4)(4), [Bzm(O-C(3)H(6)-(dmg))(dmgH(2))]Co(III)[ClO(4)(5) and ]Im(O-C(3)H(6)-(dmg))(dmgH(2))[Co(III)]ClO(4)(6) and their precursor aqua-(3-bromopropyl)cobaloximes (1) were investigated by UV-Vis spectroscopy. The products of photolytic solutions were characterized by both ESI-MS and (1)H-NMR techniques. Our results revealed a carbon-center radical that is produced from Co-C bond cleavage under photolysis might be linked to the equatorial ligand and thus retained in the proximity of Co(II)-complex. The thermo-gravimetric analysis of complex 2 gives the same conclusion.

Photolysis Secondary Products of Cobaloximes and Imino/Oxime Compounds Controlled by Steric Hindrance Imposed by the Lewis Base

“…3,4a Accordingly, information on the structure and reactions in which the cobalt(II) species are involved may be achieved by studying photolysis and thermolysis of B 12 compounds and related models. 21,[27][28][29][30][31][32][33] For B 12 model compounds several studies concerning anaerobic photolysis in protic and aprotic solvents of alkylcobaloximes with nitrogen [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] and phosphorus 33 donor bases have appeared in the literature and more recently a study of photolysis of methylaquacobinamide in the presence of N-donor ligands, which impose variable electronic and steric effects, 21 although no work on photolysis of imino/oxime compounds has been reported.…”

Synthesis, spectroscopic characterization, axial base coordination equilibrium and photolytic kinetics studies of a new coenzyme B12analogue-3′-deoxy-2′,3′-anhydrothymidylcobalamin

“…All samples for photolysis were prepared in aqueous solutions at 25 • C under anaerobic conditions and red light. 16 A solution of about 10 −3 M was loaded into a quartz cuvette (1 cm path length) and degassed for 30 min by vigorous bubbling of nitrogen gas. The cuvette was sealed with a Teflon cap under nitrogen pressure, and then exposed to a 8 W white light lamp, placed at a distance of 4 cm from the sample cuvette.…”