Synthesis and electron spin resonance study of a tetradentate copper(II) mercaptobenzaldimine complex

The X-band e.s.r, spectrum of a copper(II) Schiff-base complex, 2,2?- [ethylenebis(nitrilomethylidyne)]-bis(benzenethiolato-S,N)copper(II) (Cu(mben)), has been determined in frozen toluene-chloroform solutions. The complicated line shape has been simulated by a computer program incorporating symmetry around the copper lower than axial, together with a nitrogen hyperfine pattern calculated for two cis nitrogen atoms. The e.s.r parameters are compared with those obtained for two other thio Schiff-base chelates and with those for the salicylaldimine analogue, Cu(salen). Metal-ligand covalency parameters estimated from the e.s.r. parameters are discussed briefly.