Synthesis and spectroscopic characterization of [ReH5(triphos)] and [ReH6(triphos)]+[triphos = PPh(CH2CH2PPh2)2]

Abstract

Reaction of mer-[ReCl₃(PMePh₂)₃] with PPh(CH₂CH₂PPh₂)₂(triphos) in refluxing toluene leads to the formation of [ReCl₃(triphos)]1. Treatment of 1 with LiAlH₄ in refluxing Et₂O gives [ReH₅(triphos)]2. Protonation of 2 with HBF₄·OEt₂ gives [ReH₆(triphos)]⁺3. Deprotonation of 3 with NEt₃ regenerates 2 quantitatively. The spectroscopic data for compound 3 suggest that it is near the classical/non-classical borderline but exists in solution as a single tautomer only. An estimate of 1.17 Å for the H–H distance of the η²-H₂ ligand in 3 was obtained from the T₁ data and previous structural work.