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Organo-bridged dicobaloximes with four different dioximes Py(L) 2 CoCH 2 -R-CH 2 Co(L) 2 Py (L ) dmgH, dpgH, chgH, and gH) have been synthesized and characterized by 1 H and 13 C NMR and FAB mass spectroscopy. The cis influencing order observed in dicobaloximes is similar to the previously observed order in monocobaloximes. The cyclic voltammetric results show that an irreversible single-step two-electron reduction of Co III to Co I takes place. The Co-C bond in 4a cleaves during crystallization and results in the formation of o-vinylbenzyl cobaloxime. The variable-temperature 1 H NMR study suggests that the Co-C bond rotation is restricted and its magnitude depends on both the nature of the bridging ligand and the dioxime.

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Xylylene-bridged dicobaloximes with a substituent at the 2-position having varying electronic and steric properties have been synthesized and characterized by 1 H and 13 C NMR spectroscopy. The variable-temperature 1 H NMR study of these complexes shows that the electronic cis influence is an important phenomenon for the Co-C bond rotation. The coalescence temperature of the dioxime protons correlates well with the ortho substituent constant. The crystal structure of a 2-nitro-m-xylylene-bridged dicobaloxime, Py(dmgHPy, is reported. The X-ray structural data support the 1 H NMR findings. Experimental SectionGeneral Comments. Cobalt chloride hexahydrate, dimethylglyoxime (SD Fine, India), diphenylglyoxime, 2-fluoro- † Dedicated to Prof.

Development of clean and renewable energy sources has emerged as one of the major interests due to the environmental issues caused by the fossil fuels. Presently a huge amount of interest has been devoted in developing the cost effective alternative energy sources and hydrogen gas has been considered as one of the substitutes for fossil fuels. Initially noble metals like Platinum was employed as a catalyst for hydrogen generation but they are costly. So, recently first row transition metal based catalysts have been utilized for the production of hydrogen gas since these metals are cost effective and earth copious. Among the first row transition metal catalysts, cobalt complexes in particular cobaloximes have been given importance as capable catalysts for hydrogen production. This review discusses about the recent advances in the electrochemistry and the various approaches employed towards the attachment of the cobaloxime complexes on the electrode surface and their electrocatalytic behaviour.

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