H Activation and Direct Access to Terminal Nitride and -P Complexes by an Acceptor-Free Rhenium(II) β-Diketiminate.

The rhenium(II) complex Re(η-Cp)(BDI) (; BDI = ,'-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate; Cp = cyclopentadienyl) was subjected to a number of reactivity studies that highlight its unique combination of oxidation state and acceptor-free coordination environment. In the reactions under study we found that this low-valent paramagnetic species yields diamagnetic rhenium(III) or rhenium(V) products, indicating a combination of reducing power and radical character are the primary variables that control its reactivity. Namely, has been found to promote the cleavage of dihydrogen to yield the rhenium(III) hydride Re(H)(η-Cp)(BDI) (), as well as the three-electron reduction of organic azides to yield a rhenium(V) terminal nitride complex NRe(η-Cp)(BDI) (), which features a low-hapticity Cp ligand. Additionally, we found that readily activates white phosphorus (P) to form the rhenium(V) -P complex (-P)Re(η-Cp)(BDI) (). One-electron oxidation of gave the paramagnetic rhenium(VI) salt [(-P)Re(η-Cp)(BDI)][OTf] (), which was characterized by electron paramagnetic resonance and electron-nuclear double resonance spectroscopy spectroscopies. Density functional theory calculations and X-ray crystallography also provided a useful basis for understanding the reactivity and electronic structure of and its derivatives.