ESR studies of low-spin [N 1,N 4-bis(salicylidene)-S-alkyl-isothiosemicarbazonato]cobalt(II) complexes—II. Adducts of nitrogen-, phosphorus-, arsenic-, oxygen- and sulphur-donor bases

Abstract

ESR spectra of [Co(Me,H,H)·H 2O] [Me,H,H = N 1,N 4-bis(salicylidene)-S-methyl-isothiosemicarbazone 2−] and its adducts with ligands containing nitrogen (pyridine, 4-CN pyridine, α- and γ-picoline, N-methyl- and N-ethylimidazole), phosphorus (tributyl-, triphenyl-, diphenylmethyl-, diphenylethylphosphine, triphenyl- and triethylphosphite), arsenic (triphenyl arsine), oxygen (DMF, THF) and sulphur (dimethyl-, diethyl-, diphenyl- and methylphenylsulphide) donor bases were studied in frozen solutions. All spectra were indicative of low-spin cobalt(II) centres with predominantly d z 2 character of the ground state. The determined values of A Co and g tensor components and superhyperfine coupling constants observed for base donor atoms indicated the formation of five-coordinate monoadducts. For some nitrogen bases (pyridine, 4-CN pyridine and γ-picoline) the formation of 1 : 2 six-coordinate bis-adducts was also observed. The bonding parameters were calculated. The activity of the N-donor adducts towards dioxygen is also reported.