Electron spin resonance spectra and structure of some group IV and group V derivatives of dicyclopentadienyltitanium(III)

Abstract

The e.s.r. spectra have been obtained from frozen solutions of some Group IV and Group V derivatives of titanocene. All the complexes have an intermediate g-component of 1·988 ± 0·006, and it is postulated that this value is associated with the cyclopentadienyl groups, whilst the low g-value is connected with the remaining ligands. The trends in A_iso(Ti) and g(average) are explained in terms of the electron-donor character of the ligands and the resulting s-orbital expansion. Spin-polarisation is believed to be the dominant mechanism for the aquisition of spin by the ligands, although for the Group V derivatives this negative spin density is reduced by direct overlap between the lone-pair orbitals and the titanium 3d_z² orbital containing the unpaired electron.