title: Synthesis, neutron structure, and reactivity of the bis(dihydrogen) complex RuH2(eta(2)-H2)2(PCyp3)2 stabilized by two tricyclopentylphosphines.
abstract: Treatment of Ru(eta4-C8H12)(eta6-C8H10) with 3 bar H2 in the presence of 2 equiv of tricyclopentylphosphine (PCyp3) in pentane resulted in the isolation of the new bis(dihydrogen) complex RuH2(eta2-H2)2(PCyp3)2 (2), characterized by NMR and single-crystal X-ray and neutron diffraction. The single-crystal neutron diffraction study is the first carried out for a bis(dihydrogen) complex. The coordination geometry around the metal center is a distorted octahedron defined by the two phosphines in a trans configuration (making an angle of 168.9(1) degrees ), two cis dihydrogen ligands, and two hydrides trans to them, defining the equatorial plane. The H-H bond distances (0.825(8) and 0.835(8) A) are characteristic of two "unstretched" dihydrogen ligands. H/D exchange between the Ru-H and the C-D bonds of deuterated benzene is observed within 1 h, leading to the formation of various isotopomers RuHxD6-x(PCyp3)2 (with x = 0-6). 2 is a catalyst precursor for ethylene coupling (20 bar, 293 K) to a functionalized arene (Murai reaction). We found a 90% conversion of acetophenone to 2-ethylacetophenone within 35 min, whereas 10 h was needed in the same conditions using the analogous tricyclohexylphosphine complex, RuH2(eta2-H2)2(PCy3)2, the best catalyst precursor, at room temperature, prior to this work.
authors.affiliation: Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse Cedex 04, France.
authors.forename: Mary
authors.initials: M
authors.lastname: Grellier
authors.forename: Laure
authors.initials: L
authors.lastname: Vendier
authors.forename: Bruno
authors.initials: B
authors.lastname: Chaudret
authors.forename: Alberto
authors.initials: A
authors.lastname: Albinati
authors.forename: Silvia
authors.initials: S
authors.lastname: Rizzato
authors.forename: Sax
authors.initials: S
authors.lastname: Mason
authors.forename: Sylviane
authors.initials: S
authors.lastname: Sabo-Etienne