The single-crystal electronic and electron spin resonance spectra of bis-(N-n-propylsalicylaldiminato)copper(II)

Abstract

The polarised single-crystal electronic and e.s.r. spectra of bis-(N-n-propylsalicylaldiminato)copper(II) have been recorded. The correlation of the single-crystal g-values and the crystallographic data suggests an approximate d_x²–y² ground state for the CuO₂N₂ chromophore. The electronic spectra have been assigned in D_2h effective symmetry and yield an tentative partial one-electron orbital sequence d_x²–y² > d_xz > d_yz > d_z² with the position of the d_xy orbital uncertain, but probably near to the d_xz and d_yz orbitals. The combined spin–orbit and orbital reduction parameters have been evaluated and suggest significant out-of-the-plane π-bonding and possible some inplane π-bonding. The results are compared with the published data on Cu(N-methylsalicylaldimine)₂(the electronic spectra of which are reassigned with a d_x²–y² ground state) and with the less certain data on Cu[(±)-NN-diethyl-α-alanine]₂.