Single-crystal electronic and electron spin resonance spectra of 2,2′-bipyridylbis(hexafluoroacetylacetonato)copper(II)

Abstract

The polarised single-crystal electronic and e.s.r. spectra of 2,2′-bipyridylbis(hexafluoroacetylacetonato)copper(II) have been measured. The correlation of the single-crystal electronic and e.s.r. spectral data with the crystallographic data indicates a d_xy ground state. The polarised single-crystal electronic spectra are interpreted in D₂ effective symmetry and yield a tentative one-electron orbital sequence d_xy > d_z² > d_yz > d_xz > d_x²–y². The energy of the d_z²→d_xy transition (9·4 kk) is consistent with the restricted tetragonal distortion suggested by the crystal structure. The combined spin-orbit and orbital-reduction parameters are calculated and the values discussed in terms of π-bonding within the molecule.