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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.