1585159-98-3Relevant academic research and scientific papers
Synthesis, characterization, and reactivity of ruthenium hydride complexes of N-centered triphosphine ligands
Phanopoulos, Andreas,Brown, Neil J.,White, Andrew J. P.,Long, Nicholas J.,Miller, Philip W.
, p. 3742 - 3752 (2014)
The reactivity of the novel tridentate phosphine ligand N(CH 2PCyp2)3 (N-triphosCyp, 2; Cyp = cyclopentyl) with various ruthenium complexes was investigated and compared that of to the less sterically bulky and less electron donating phenyl derivative N(CH2PPh2)3 (N-triphosPh, 1). One of these complexes was subsequently investigated for reactivity toward levulinic acid, a potentially important biorenewable feedstock. Reaction of ligands 1 and 2 with the precursors [Ru(COD)(methylallyl)2] (COD = 1,5-cycloocatadiene) and [RuH2(PPh3)4] gave the tridentate coordination complexes [Ru(tmm){N(CH2PR2) 3-δ3P}] (R = Ph (3), Cyp (4); tmm = trimethylenemethane) and [RuH2(PPh3){N(CH 2PR2)3-δ3P}] (R = Ph (5), Cyp (6)), respectively. Ligands 1 and 2 displayed different reactivities with [Ru3(CO)12]. Ligand 1 gave the tridentate dicarbonyl complex [Ru(CO)2{N(CH2PPh2)3- δ3P}] (7), while 2 gave the bidentate, tricarbonyl [Ru(CO) 3{N(CH2PCyp2)3-δ2P} ] (8). This was attributed to the greater electron-donating characteristics of 2, requiring further stabilization on coordination to the electron-rich Ru(0) center by more CO ligands. Complex 7 was activated via oxidation using AgOTf and O2, giving the Ru(II) complexes [Ru(CO)2(OTf){N(CH 2PPh2)3-δ3P}](OTf) (9) and [Ru(CO3)(CO){N(CH2PPh2)3- δ3P}] (11), respectively. Hydrogenation of these complexes under hydrogen pressures of 3-15 bar gave the monohydride and dihydride complexes [RuH(CO)2{N(CH2PPh2) 3-δ3P}] (10) and [RuH2(CO){N(CH 2PPh2)3-δ3P}] (12), respectively. Complex 12 was found to be unreactive toward levulinic acid (LA) unless activated by reaction with NH4PF6 in acetonitrile, forming [RuH(CO)(MeCN){N(CH2PPh2)3- δ3P}](PF6) (13), which reacted cleanly with LA to form [Ru(CO){N(CH2PPh2)3-δ3P} {CH3CO(CH2)2CO2H- δ2O}](PF6) (14). Complexes 3, 5, 7, 8, 11, and 12 were characterized by single-crystal X-ray crystallography.
