Frustrated Lewis Pair Chelation and Reactivity of Complexed Parent Iminoborane and Aminoborane

• Published in: Inorganic chemistry Vol. 61; no. 41; pp. 16430 - 16440
• Main Authors: Omaña, Alvaro A., Watt, Ryan, Zhou, Yuqiao, Ferguson, Michael J., Rivard, Eric
• Format: Journal Article
• Language: English
• Published: American Chemical Society 17.10.2022
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.2c02535

An intramolecular phosphine–borane frustrated Lewis pair (FLP) chelate, i Pr2P­(C6H4)­BCy2 or PB (Cy = cyclohexyl), was used to coordinate aminoborane (H2BNH2) and iminoborane (HBNH) units via donor–acceptor stabilization. Attempts to induce dehydrogenation from these B–N adducts with known metal catalysts (or pre-catalysts) have been unsuccessful thus far, and related observations were noted with an H2BNH2 complex supported by a modified FLP chelate bearing a geometrically constrained bicyclic 9-borabicyclo(3.3.1)­nonane (BBN) unit. Treatment of the iminoborane adduct [PB­{HBNH}] with a chlorinating agent led to ligand activation via B–C bond cleavage instead of the expected H/Cl exchange at boron to give [PB­{ClBNH}]. Nucleophilic attack at the boron center in [PB­{HBNH}] was observed upon addition of BnK (Bn = benzyl), yielding the amidoborate complex [PB­{H­(Bn)­BNH}­{K­(THF)2}].