Ga/P-Based Ambiphilic Chelates and Their Reactivities with Main Group Elements

The synthesis of two ambiphilic Ga/P-containing frustrated Lewis pairs (FLPs) [iPr2P(C6H4)GaMes2] (PGaMes2, 1, Mes = 2,4,6-Me3C6H2) and [{iPr2P(C6H4)}2GaMes] (P2GaMes, 2) is reported. Motivated by the possibly higher degrees of Lewis acidity at the Ga centers in 1 and 2 compared to known-boron based chelates, these new Ga/P FLPs were reacted with soft main group elements, such as Te, as well as exploration of their ability to coordinate the parent aminoborane H2B–NH2 (generated via the dehydrogenation of H3B·NH3). In contrast to the known/stable chelate [iPr2P(C6H4)BCy2{H2BNH2}] (Cy = cyclohexyl), the corresponding Ga/P adduct [P2GaMes{H2BNH2}] (8) is unstable and releases B–N units such as borazine [HBNH]3 over time, which is partially attributed to a hard–soft acid–base mismatch between N and Ga.