In all cases, VZZ is oriented along the M-L axis, where L is the neutral donor, and perpendicular to the plane containing the siloxide ligands (SI S6). Thus, modulation of the magnitude of VZZ is related to the extent of donation from the neutral donor to the Ga nucleus. By comparing the contributions arising from the neutral donor (M-L is aligned along VZZ), VZZ correlates with the σ-donor ability of L (i.e.