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Bifunctional activation of amine-boranes by the W/Pd bimetallic analogs of "frustrated Lewis pairs".

Elena S OsipovaEkaterina S GulyaevaEvgenii I GutsulVladislava A KirkinaAlexander A PavlovYulia V NelyubinaAndrea RossinMaurizio PeruzziniLina M EpsteinNatalia V BelkovaOleg A FilippovElena S Shubina
Published in: Chemical science (2021)
The reaction between basic [(PCP)Pd(H)] (PCP = 2,6-(CH2P(t-C4H9)2)2C6H4) and acidic [LWH(CO)3] (L = Cp (1a), Tp (1b); Cp = η5-cyclopentadienyl, Tp = κ3-hydridotris(pyrazolyl)borate) leads to the formation of bimolecular complexes [LW(CO)2(μ-CO)⋯Pd(PCP)] (4a, 4b), which catalyze amine-borane (Me2NHBH3, t BuNH2BH3) dehydrogenation. The combination of variable-temperature (1H, 31P{1H}, 11B NMR and IR) spectroscopies and computational (ωB97XD/def2-TZVP) studies reveal the formation of an η1-borane complex [(PCP)Pd(Me2NHBH3)]+[LW(CO3)]- (5) in the first step, where a BH bond strongly binds palladium and an amine group is hydrogen-bonded to tungsten. The subsequent intracomplex proton transfer is the rate-determining step, followed by an almost barrierless hydride transfer. Bimetallic species 4 are easily regenerated through hydrogen evolution in the reaction between two hydrides.
Keyphrases
  • electron transfer
  • magnetic resonance
  • metal organic framework
  • ionic liquid
  • molecular docking
  • single cell
  • room temperature
  • highly efficient