Ruthenium agostic (Phosphinoaryl)borane complexes: Multinuclear solid-state and solution NMR, X-ray, and DFT studies

Abstract

The reactivity of the (o-phosphinophenyl)(amino)borane compound HB(N iPr 2)C 6H 4(o-PPh 2) prepared from Li(C 6H 4)PPh 2 and HBCl(N iPr 2) toward the bis(dihydrogen) complex RuH 2(H 2) 2(PCy 3) 2 (1) was studied by a combination of DFT, X-ray, and multinuclear NMR techniques including solid-state NMR, a technique rarely employed in organometallic chemistry. The study showed that the complex RuH 2{HB(N iPr 2)C 6H 4(o-PPh 2)} (PCy 3) 2 (3), isolated in excellent yield as yellow crystals and characterized by X-ray diffraction, led in solution to PCy 3 dissociation and formation of an unsaturated 16-electron complex RuH 2{HB(N iPr 2)C 6H 4(o-PPh 2)}(PCy 3) (4), with a hydride trans to a vacant site. In both cases, the (phosphinoaryl)(amino)borane acts as a bifunctional ligand through the phosphine moiety and a Ru-H-B interaction, thus featuring an agostic interaction. © 2011 American Chemical Society.