REACTIONS OF MOLECULAR-HYDROGEN COMPLEXES [RUH(ETA-2-H2)P4]BF4 WITH ALKYNES - PREPARATION AND CRYSTAL-STRUCTURE OF THE [RU(ETA-3-(PARA-TOLYL)C3CH(PARA-TOLYL))(PHP(OET)2)4]BPH4 DERIVATIVE

Complexes [RuH(eta-2-H2)P4]BF4[P = PhP(OEt)2, P(OEt)3, P(OMe)3] react with terminal alkynes HC = CR (R = Ph, p-tolyl, CMe3,SiMe3) to yield alkenes H2C = CHR and [Ru(eta-3-RC3CHR)P4]+ derivatives. Selective hydrogenation of the alkyne to alkene by the eta-2-H2 ruthenium catalyst precursor in mild conditions was also observed. The structure of the compound [Ru{eta-3-(p-tolyl)C3CH(p-tolyl)}{PhP(OEt2}4]BpH4 was determined crystallographically: space group P2(1), a = 12.497 (5) angstrom, b = 24.407 (8) angstrom, c = 12.763 (5) angstrom, beta = 96.89 (2)-degrees, Z = 2; final R = 0.057 and R(w) = 0.074. The ruthenium atom has a pseudooctahedral coordination with four phosphite groups and the eta-3-RC3CHR ligand. The [Ru(eta-3-RC3CHR)P4]+ derivatives react with acetylacetone to afford [Ru(acac)P4]+ cations and organic compounds (Z)-R(H)C = C(H)C = CR. The reaction of other alkynes [MeO2CC = CCO2Me, RC = CR (R = Me, Ph)] toward the [RuH(eta-2-H2)P4]BF4 complexes was also investigated and the synthesis of the vinyl derivatives [Ru{C(CO2Me) = C(H)CO2Me}{PhP-(OEt)2}4]PF6 achieved. Characterization of the complexes by IR and H-1 and P-31{H-1} NMR spectra is also discussed.