Dinitrogen Fixation by Vanadium Complexes with a Triamidoamine Ligand

Dinitrogen-divanadium complexes with triamidoamine ligands, 1–3, were synthesized and characterized by resonance Raman, UV–vis, and NMR spectroscopy and elemental and X-ray structure analyses. X-ray structure analyses reveal that all three of the complexes have a dimeric structure with a μ-N2 ligand (N–N bond length 1.200–1.221 A). Resonance Raman and NMR spectra of 1–3 in solution show that these complexes maintain a dimeric structure in benzene and toluene solutions. 15N NMR spectra of 1 and 3 have peaks assignable to μ-N2 ligands at 33.4 and 27.6 ppm, respectively, but 2 does not have a similar peak under the same conditions. In 51V NMR spectra, the peaks of vanadium ions were observed at −173.3, −143.8, and −240.2 ppm, respectively, which are in a higher magnetic field region in comparison to those of dinitrogen-divanadium complexes reported previously. The structure and electronic properties of 1 are supported by DFT calculations. Additionally, all complexes react with excess amounts of M[C10H8] (M =...