Varying the Lewis Base Coordination of the Y2N2 Core in the Reduced Dinitrogen Complexes {[(Me3Si)2N]2(L)Y}2(μ-η2:η2-N2) (L = Benzonitrile, Pyridines, Triphenylphosphine Oxide, and Trimethylamine N-Oxide)

The effect of the neutral donor ligand, L, on the Ln2N2 core in the (NN)2– complexes, [A2(L)Ln]2(μ-η2:η2-N2) (Ln = Sc, Y, lanthanide; A = monoanion; L = neutral ligand), is unknown since all of the crystallographically characterized examples were obtained with L = tetrahydrofuran (THF). To explore variation in L, displacement reactions between {[(Me3Si)2N]2(THF)Y}2(μ-η2:η2-N2), 1, and benzonitrile, pyridine (py), 4-dimethylaminopyridine (DMAP), triphenylphosphine oxide, and trimethylamine N-oxide were investigated. THF is displaced by all of these ligands to form {[(Me3Si)2N]2(L)Y}2(μ-η2:η2-N2) complexes (L = PhCN, 2; py, 3; DMAP, 4; Ph3PO, 5; Me3NO, 6) that were fully characterized by analytical, spectroscopic, density functional theory, and X-ray crystallographic methods. The crystal structures of the Y2N2 cores in 2–5 are similar to that in 1 with N–N bond distances between 1.255(3) Å and 1.274(3) Å, but X-ray analysis of the N–N distance in 6 shows it to be shorter: 1.198(3) Å.