Single-crystal electronic and electron spin resonance spectra of dichlorobis-(2-methylpyridine)copper(II)

Abstract

The single-crystal polarised electronic and e.s.r. spectra of dichlorobis-(2-methylpyridine)copper(II) have been measured. The single-crystal g-values correlate with the monomeric local copper(II) co-ordinate axes and not with the co-ordinate axes of the dinuclear copper(II) species; they suggest a d_x²–y² ground state. The polarised single-crystal electronic spectra have been interpreted in both D₂ and C_2v effective symmetries. Reasons are given why the latter symmetry which yields the tentative one-electron orbital sequence d_x²–y² > d_yz > d_z²≈d_xz, with the position of the d_xy orbital uncertain, is preferred. The orbital reduction parameters are evaluated and discussed in terms of π-bonding within the molecule.