Synthesis and dehydrocoupling reactivity of iron and ruthenium phosphine-borane complexes

摘要

The Fe and Ru phosphine-borane complexes CpM(CO)(2)PPh2 center dot BH3 (1, M = Fe, 4, M = Ru) were synthesized utilizing the reaction of the phosphine-borane anion Li[PPh2 center dot BH3] with the iodo complexes CpM(CO)(2)I. The Fe complex 1 reacted with PMe3 to yield CpFe(CO)(PMe3)(PPh2 center dot BH3) (2) and CpFe(PMe3)(2)(PPh2 center dot BH3) (3) whereas the Ru species 4 gave only CpRu(CO)(PMe3)(PPh2 center dot BH3) (5). The complexes 1-5 were characterized by H-1, B-11, C-13 and IT 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 center dot BH, 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 center dot BH2 center dot PPh2 center dot BH3 in the melt at elevated temperature (120 degrees C). The carbonyl Fe, (CO)g also functioned as a dehydrocoupling catalyst under similar conditions. Complex 1 and Fe-2(CO)(9) represent the first reported active Fe complexes for the catalytic dehydrocoupling of phosphine-borane adducts.