Electric field gradient models based on the geometry of the coordination sphere

Abstract

A complication in NQR studies of many organometallic complexes of contemporary interest is the low molecular symmetry. Guidance is needed on the principal axis orientation and geometric effects of the electric field gradient. In this paper a “coordination sphere” model based on electrostatic charges is described for the fac-a 3b 2c, fac-a 3b 2 ligand geometries. Experimental tests are made using e 2Qq/h and η for a number of organometallic Co and Mn complexes having these geometries. The model is surprisingly successful if b and c are single-atom donor ligands. π-Olefin and some other strong π-acceptor ligands yield poorer results. The coordination sphere model is a useful augment to the Townes-Dailey model.