The Fe and Ru phosphine–borane complexes CpM(CO)2PPh2·BH3 (1, M = Fe, 4, M = Ru) were synthesized utilizing the reaction of the phosphine–borane anion Li[PPh2·BH3] with the iodo complexes CpM(CO)2I. The Fe complex 1 reacted with PMe3 to yield CpFe(CO)(PMe3)(PPh2·BH3) (2) and CpFe(PMe3)2(PPh2·BH3) (3) whereas the Ru species 4 gave only CpRu(CO)(PMe3)(PPh2·BH3) (5). The complexes 1–5 were characterized by 1H, 11B, 13C and 31P NMR spectroscopy, MS, IR and X-ray crystallography for 1 to 4, and EA for 1, 2 and 4. The reactivity of 1 and 4 towards PPh2H·BH3 was explored. Although no stoichiometric reactions were detected under mild conditions, both 1 and 4 were found to function as dehydrocoupling catalysts to afford Ph2PH·BH2·PPh2·BH3 in the melt at elevated temperature (120 °C). The carbonyl Fe2(CO)9 also functioned as a dehydrocoupling catalyst under similar conditions. Complex 1 and Fe2(CO)9 represent the first reported active Fe complexes for the catalytic dehydrocoupling of phosphine–borane adducts.
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