Magnetic and Spectral Studies on Cobalt(II) and Copper(II) Salts of Methylsulfuric, Trifluoromethylsulfuric, and Paratolylsulfuric Acids

The compounds Co(CF3SO3)2, Cu(CF3SO3)2, Co(CH3SO3)2, Cu(CH3SO3)2, Co(p-CH3C6H4SO3)2, and Cu(p-CH3C6H4SO3)2 have been prepared and infrared spectra, electronic spectra, and magnetic susceptibility studies are reported. Electronic spectral and magnetic studies have also been made on Cu(FSO3)2 and previously published data on Co(FSO3)2 are reexamined here. The studies indicate that in all salts the metal ions are hexacoordinated by oxygen atoms provided by anions acting as tridentate bridging ligands. The MO6 skeleton is significantly distorted from regular octahedral geometry for all salts with the possible exceptions of Co(FSO3)2, Co(p-CH3C6H4SO3)2, and Co(CH3SO3)2. Values of the spin–orbit coupling constants for the salts, as estimated from the magnetic studies, decrease with increasing anion basicity, suggesting a correlation between basicity and the degree of covalent character in the metal–anion bonds. In the case of the cobalt salts the interelectron repulsion parameter B also seems to decrease with increasing anion basicity.