Electronic effects on the reactivity of copper mono-bipyridine complexes

Electronic effects on the synthesis, structure and reactivity of copper 2,2′-bipyridine (bpy) complexes of formula [Cu(4,4′-R2-2,2′-bipyridine)]Cl2, where R = Cl, CH3, OCH3, and [Cu(4,4′-R2-2,2′-bipyridine)](NO3)2, where R = NO2, Cl, are reported. Pure complexes were formed, as shown by elemental analysis, for mono bpy Cu complexes when bpy ligands with groups R = Cl, CH3 or OCH3 were pre-dissolved in chloroform and added to methanol solution of CuCl2 in a 1:1 molar ratio (compounds 1–3). Mono bpy Cu complexes were obtained when bpy ligands with groups R = Cl and NO2 were pre-dissolved in THF and added to methanol solution of Cu(NO3)2 in a 1:1 molar ratio (compounds 4 and 5). Under the same conditions, for R = OCH3 the bis bipyridine complex [Cu(4,4′-(OCH3)2-2,2′-bipyridine)2(NO3)](NO3) (6) was formed. Suitable crystals of 4 and 6·CH3OH for X-ray analysis were formed by the slow evaporation of solvent. The main electronic effect for the catalytic hydrolysis of methyl parathion by Cu(4,4′-R2-2,2-bipyridine)2+(aq), where R = Cl, H and CH3, was a shift in the acid dissociation constant of coordinated water and a small increase in the second order rate constant, k2, measured at pH 9.1.