The addition of 4 equiv of LiN=C-t-Bu-2 to CrCl3, MoCl5, and WCl6 in diethyl ether produced the complexes M(N=C-t-Bu-2)(4) (M = Cr, Mo, W). Single-crystal X-ray diffraction studies revealed that the molecules have flattened tetrahedral geometries with virtual D-2d symmetry in the solid state. H-1 and C-13 NMR spectra indicated that the complexes are diamagnetic, and a qualitative MO analysis showed that the orthogonal pi-donor and -acceptor orbitals of the ketimide ligand cooperatively split the d(xy) and d(z2) orbitals sufficiently to allow spin pairing in the d(xy) orbital. A more sophisticated quantum-mechanical analysis of Cr(N=C-t-Bu-2)(4) using density functional/molecular mechanics methods confirmed the qualitative analysis by showing that the singlet state is 27 kcal/mol more stable than the triplet state.