Synthesis, Electronic Structure, and Magnetism of [Ni(6-Mes)2]+: A Two-Coordinate Nickel(I) Complex Stabilized by Bulky N‑Heterocyclic Carbenes

The two-coordinate cationic Ni­(I) bis-N-heterocyclic carbene complex [Ni­(6-Mes)2]Br (1) [6-Mes =1,3-bis­(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene] has been structurally characterized and displays a highly linear geometry with a C–Ni–C angle of 179.27(13)°. Density functional theory calculations revealed that the five occupied metal-based orbitals are split in an approximate 2:1:2 pattern. Significant magnetic anisotropy results from this orbital degeneracy, leading to single-ion magnet (SIM) behavior.