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 dx2–y2 ground state for the CuO2N2 chromophore. The electronic spectra have been assigned in D2h effective symmetry and yield an tentative partial one-electron orbital sequence dx2–y2 > dxz > dyz > dz2 with the position of the dxy orbital uncertain, but probably near to the dxz and dyz 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 dx2–y2 ground state) and with the less certain data on Cu[(±)-NN-diethyl-α-alanine]2.