Co-ordination state of copper(II) ion in Cu(O2CMe)2–pyridine derivative–diluent mixtures; the steric effect of the amine ligand

Electronic spectra (360–800 nm) and electrolytic conductivities have been measured for the Cu(O2CMe)2–L–chlorobenzene systems (L = 2-chloro-, 2-methyl-, 2-ethyl-, 2,4-dimethyl-, or 2,6-dimethyl-pyridine) and Kth for the equilibrium 2[Cu(O2CMe)2L2] ⇌ [Cu2(O2CMe)4L2] + 2L calculated. The results are compared with those obtained for non-α-substituted pyridines as ligands. A strong steric effect on the co-ordination equilibria as well as on the stereochemistry and solvation of the mononuclear [Cu(O2CMe)2L2] complexes has been evidenced and discussed.