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.

ABSTRACT

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.