Pyridyl-Substituted Indenyl Ruthenium Complexes: Synthesis, Structures, and Reactivities

Aerobic oxidation of primary benzylic amines to amides and nitriles catalyzed by ruthenium carbonyl clusters carrying N,O-bidentate ligands

Four trinuclear ruthenium carbonyl clusters, (6-BrPyCHRO)₂Ru₃(CO)₈ (R = 4-OCH₃C₆H₄, 1a; R = 4-BrC₆H₄, 1b) and (2-OC₆H₄-HC[double bond, length as m-dash]N-C₆H₄R)₂Ru₃(CO)₈ (R = 4-OCH₃, 2a; R = 4-Br, 2b), were synthesized from the reactions of Ru₃(CO)₁₂ with the corresponding N,O-bidentate ligands (two pyridyl alcohols and two Schiff bases) respectively in a ratio of 1 : 2. Three new complexes 1b, 2a and 2b have been fully characterized by elemental analysis, FT-IR, NMR and X-ray crystallography. The catalytic activity of these ruthenium complexes for the aerobic oxidation of primary benzylic amines to amides and nitriles in the presence of t-BuOK was investigated, of which the Schiff base complex 2a was found to exhibit the highest activity.

Synthesis and Structures of Ruthenium Carbonyl Complexes Bearing Pyridine-Alkoxide Ligands and Their Catalytic Activity in Alcohol Oxidation

Reaction of Ru₃(CO)₁₂ with two equiv of 6-bromopyridine alcohols 6-bromopyCHROH [(R = C₆H₅ (L1); R = 4-CH₃C₆H₄ (L2); R = 4-OMeC₆H₄ (L3); R = 4-ClC₆H₄ (L4); (R = 4-CF₃C₆H₄ (L5); R = 2-OMeC₆H₄ (L6); R = 2-CF₃C₆H₄ (L7)] and 6-bromopyC(Me)₂OH (L8) in refluxing xylene afforded novel trinuclear ruthenium complexes [6-bromopyCHRO]₂Ru₃(CO)₈ (1a-1g) and [6-bromopyC(Me)₂O]₂Ru₃(CO)₈ (1h). These complexes were characterized by FT-IR and NMR spectroscopy as well as elemental analysis. The structures of all the complexes were further confirmed by X-ray crystallographic analysis. In the presence of tert-butyl hydroperoxide (TBHP) as the source of oxidant, complexes 1a-1h displayed high catalytic activities for oxidation of primary and secondary alcohols and most of oxidation reactions could be completed within 1 h at room temperature.

Bidentate Ru(ii)-NC complexes as catalysts for the dehydrogenative reaction from primary alcohols to carboxylic acids

Complex 1 is active for alcohol dehydrogenative reactions, and two critical intermediates were isolated and characterized.

Intramolecular cyclization of a diruthenium complex: insight into the mechanism of heteroatom-directed intramolecular C-H/olefin coupling reactions

Complex 2, synthesized by the reaction of {(C5H4N)(μ2-η(5):η(1)-C9H5)}Ru3(CO)9 (1) with 1,5-hexadiene, could further transform to another diruthenium complex 3via intramolecular carbometalation. The results are relevant to the mechanism of transition-metal catalyzed heteroatom-directed intramolecular C-H/olefin coupling reactions.

Reactivity of a trinuclear ruthenium complex involving C–H activation and insertion of alkene

Synthesis, structure and reactivity of a pyridyl-substituted indenyl trinuclear ruthenium complex were researched.

Phenyl substituted indenylphosphine ruthenium complexes as catalysts for dehydrogenation of alcohols

Thermal treatment of (1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (1) and (3-mesityl-1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (3) with tBuONa followed by [(η(6)-cymene)RuCl(2))](2) in methanol gave the adduct {(η(6)-cymene)RuCl(2)[(1H-inden-3-yl)PCy(2)]} (6) and {(η(6)-cymene)RuCl(2)[(3-mesityl-1H-inden-3-yl)PCy(2)]} (7), respectively. Thermal treatment of (2-phenyl-1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate (4) with tBuONa followed by [(η(6)-cymene)RuCl(2))](2) or RuCl(3)·3H(2)O in methanol gave {Ru[κ(P):(η(6)-2-phenyl-1H-inden-3-yl)PCy(2)]Cl(2)} (8). Whereas (2-mesityl-1H-inden-3-yl)dicyclohexylphosphine (5) reacted with [(η(6)-cymene)RuCl(2))](2) (in toluene) or RuCl(3)·3H(2)O (in ethanol) to afford {Ru[κ(P):(η(6)-2-mesityl-1H-inden-3-yl)PCy(2)]Cl(2)} (9). The molecular structures of complexes 6, 8 and 9 have been determined by single-crystal X-ray diffraction analysis. In addition, complexes 8 and 9 have been found to catalyze the acceptorless dehydrogenation of alcohols in toluene. 9 displayed high activity and different substrates, including cyclic and linear alcohols, were efficiently oxidized to ketones by using 2.0 mol% of catalyst.