Two-Coordinate, Nonlinear Vanadium(II) and Chromium(II) Complexes of the Silylamide Ligand–N(SiMePh2)2: Characterization and Confirmation of Orbitally Quenched Magnetic Moments in Complexes with Sub‑d5 Electron Configurations

The two-coordinate metal amide complexes V­{N­(SiMePh2)2}2 (1) and Cr­{N­(SiMe2Ph)2}2 (2) were synthesized by reaction of two equivalents of LiN­(SiMePh2)2 with VI2(THF)4 or CrCl2(THF)2 in n-hexane. Their crystal structures showed that they have bent coordination, N–V–N = 137.0(4)°, N–Cr–N = 139.19(5)°, at the metals. The vanadium complex (1) displayed no tendency to isomerize as previously observed for some V­(II) amido complexes. Curie fits of SQUID magnetic measurements afforded magnetic moments of 3.36 (1) and 4.68 (2) μB, consistent with high-spin configurations. These values are lower than the spin-only values of 3.88 and 4.90 μB expected for d3 and d4 complexes, suggesting a significant unquenched orbital angular momentum contribution to the overall moment, which is lower as a result of the positive spin–orbit coupling constants.