Structural Chemistry of Nitro-cobaloxime ComplexesSynthesized from their Chloro Precursors in [Co(DMGH)2(XPh3)Cl] (X = As & Sb)

Natural photosynthesis uses sunlight to drive the conversion of energy-poor molecules (H2O and CO2) to energy-rich ones (O2 and (CH2O)n).Scientists are working hard to develop efficient artificial photosynthetic systems toward the Holy Grail of solar-driven water splitting. High on the list of challenges is the discovery of molecules that efficiently catalyze the reduction of protons to H2. In this case one promising class of molecules are cobalt (III) complexes with equatorial diglyoxime ligands (cobaloximes) [1].Cobaloximes are among the few examples of electrocatalysts based on first-row transition metals complexes that could constitute an effective alternative to the platinum-based catalysts for the economically viable hydrogen production. Alsoover the past four decades cobaloximes have been extensively studied as structural and functional models for the coenzyme vitamin B12. A wealth of information about spectral and structural properties of a great number of cobaloximes has been collected [2]. With regards to the aforementioned properties of cobaloxime complexes, the structural chemistry of such complexes are important for their designated properties.In this study, the structural chemistry of nitro-substituted cobaloxime complexes, formed by replacing chloro ligand in the precursor complexes, [Co(DMGH)2(XPh3)Cl] in which DMGH = dimethylglyoxime monoanion and X = As or Sb., were investigated by X-ray crystallography.These complexes have been also characterized by spectroscopic methods such as FT-IR and1HNMR.