Configurations of Bis[1-(p-substituted phenyl)-1, 3-butanedionato] cobalt (II) Complexes

Abstract

The cobalt[II] complexes of two types, CoL₂ 2H₂O([1a]∼[11a]) and CoL₂([1 b]∼[11b]), were synthesized with 1-(p-substituted phenyl)-1, 3-butanediones (HL, L =p-XC₆H₄COCH COCH₃, X=NO₂[1], COOH[2], COOCH₃, [3], Br [4], Cl[5], H[6], NHCOCH₃[7], C₂H₅[8], CH₈[9], OCH₃[10], OH[11]), and their configurations were investigated by the measurements of magnetic moment and electronic spectra in the visible and ultraviolet regions. It was found that [1a]∼[11a]were monomeric octahedral in benzene, chloroform, pyridine and DMSO as well as in solid state. [1b]∼[11b]were tetrahedral in DMSO, but they changed their configurations to octahedral by the coordination of two solvent molecules in pyridine. These anhydrides except for [7b]were trimeric octahedral in solid state or in chloroform. Since the absorption bands of v, and v3 observed in the UV-visible spectra of octahedral complexes and of v2 observed for the tetrahedral complexes shifted linearly to the higher frequency side as the substituents became more electron donative, the stability of these complexes was found to increase in the order of [1]<[2]<[3]<[4]<[5]<[6]=[7]<[8]<[9]<[10]<[11]. The crystal field splitting energy 10 Dq and the electron repulsion parameter B were calculated from the p values of the →d transitions.