Alkali Metal Species in the Reversible Activation of H-2

MP(tBu)(2) (M=Li, Na, K), KH and KN(SiMe3)(2) are shown to activate HD reversibly. In the case of MP(tBu)(2) this leads to isotopic scrambling and the formation of H-2, D-2, H(D)P(tBu)(2) and MH(D) in C6D6. In toluene, KP(tBu)(2) reacts with H-2 but also leads to isotopic scrambling into the methyl groups of the solvent toluene. DFT calculations reveal that these systems effect H-2 activation via cooperative interactions with the Lewis acidic alkali metal and the basic phosphorus, carbanion, or hydride centres, mimicking frustrated Lewis pair (FLP) behaviour.