Chemically non-innocent ligands containing tricoordinate boron utilize boron’s Lewis acidity to assist the metal in chemical reactions and small molecule activation. However, reactions with oxygenated substrates often result in irreversible B-O formation, which shuts down further reactivity and impedes the use of tricoordinate boron ligands in many reactions. To address this problem, we developed a new triamidoborane-containing diphosphine ligand called TBDPhos. Triamidoboranes have lower Lewis acidity than triaryl- and trialkylboranes, and we postulated that the decreased Lewis acidity would help prevent irreversible B-O bond formation with oxygenated substrates. A series of TBDPhos complexes were prepared with Ni, Pd, and Rh and subsequently characterized by multinuclear NMR spectroscopy, single-crystal X-ray diffraction (XRD), and P K-edge X-ray absorption spectroscopy (XAS). Treating the metal complexes with H<sub>2</sub>O and MeOH in the presence of NEt<sub>3</sub> resulted in selective addition of O-H bond across a B-N bond on the ligand. Remarkably, the reactions can be reversed at room temperature by simply modifying the solvent conditions or adding weak acids, and demonstrate rare examples of reversible B-O formation at a chemically non-innocent boron ligand.

Transition metal complexes with triamidoborane-bridged diphosphines: Coordination chemistry, reactivity, and XAS studies

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.