Pyrazine bridged organodicobaloximes: a convenient one pot synthesis and cis influence studies

Pyrazine bridged benzyl dicobaloximes: Competition between π-interaction and steric crowding in crystal structure

“…Also, in the UV-Vis spectra in CHCl 3 , the shape and the k max value did not change with the addition of pyrazine to the complexes. This is similar to the observation made earlier in pyrazine bridged alkyl dicobaloximes [5].…”

“…The resonance shifts upfield on coordination to cobalt by 0.2 ppm in 1-5 whereas it shifts downfield by 0.4 ppm in 6-10 complexes. A similar trend was observed in the reported pyrazine bridged alkyl dicobloximes [5]. The dmgH methyl resonance in 1-5 appears upfield by 0.12 ppm when compared with the value in pyrazine bridged alkyl dicobloximes.…”

“…The 1 H NMR spectra of these complexes are easily assigned based on the chemical shifts. The signals are assigned according to their relative intensities and are consistent with the literature values on the related pyrazine bridged alkyl cobaloximes reported from our group [5]. All the complexes exist as six coordinate in CDCl 3 , (the solvent used for NMR study) since the cobalt bound CH 2 and dmgH/ dpgH resonance did not shift on the addition of pyrazine to the NMR sample.…”

“…Organocobaloximes have been extensively studied in the last four decades but the reports on the organo or ligand bridged dicobaloximes are limited [4,5]. Johnson et al [6] were the first to report the bridged anionic complexes of organocobaloximes.…”

“…Herlinger et al have reported the synthesis of [RCo(dmgH) 2 ] 2 -l-Pz and [RCo(dmgH) 2 ] 2 -l-4,4 0 -bipyridyl [R@Me, CH 2 Cl] by a very tedious procedure [13]. 0022 We have recently reported the synthesis and cis influence studies in pyrazine bridged alkyl dicobaloximes [5]. We could not make an extensive structural study on these complexes since we could not get a good quality crystal structure.…”