Catalytic Acceptorless Dehydrogenation of Amines with Ru(P<sup>R</sup><sub>2</sub>N<sup>R′</sup><sub>2</sub>) and Ru(dppp) Complexes

[Ru­(Cp)­(P<sup>Ph</sup><sub>2</sub>N<sup>Bn</sup><sub>2</sub>)­(MeCN)]­PF<sub>6</sub> (<b>1</b>; P<sup>Ph</sup><sub>2</sub>N<sup>Bn</sup><sub>2</sub> = 1,5-benzyl-3,7-phenyl-1,5-diaza-3,7-diphosphacyclooctane) and [Ru­(Cp)­(dppp)­(MeCN)]­PF<sub>6</sub> (<b>2</b>; dppp = 1,3-bis­(diphenylphosphino)­propane) are both active toward the acceptorless dehydrogenation of benzylamine (BnNH<sub>2</sub>) and N-heterocycles. The two catalysts have similar activities but different selectivities for dehydrogenation products. Independent synthesis of a [Ru­(Cp)­(P<sup>Ph</sup><sub>2</sub>N<sup>Bn</sup><sub>2</sub>)­(NH<sub>2</sub>Bn)]­PF<sub>6</sub> adduct (<b>3</b>) reveals the presence of a hydrogen bond between the bound amine and the pendent base of the P<sup>Ph</sup><sub>2</sub>N<sup>Bn</sup><sub>2</sub> ligand. Preliminary mechanistic studies reveal that the benzylamine adduct is not an on-cycle catalyst intermediate.