Synthesis, X-ray structure determination, and reactions of (pentamethylcyclopentadienyl)(nitrosyl)ruthenium eta(2)-arene complexes

The thermally induced reductive elimination of biphenyl fro Cp*Ru(NO)Ph(2) (1) had been reinvestigated. Careful monitoring of the reaction in aromatic solvents by H-1 NMR spectroscopy has revealed the presence of intermediate Cp*Ru(NO)(eta(2)-arene) complexes (4a, arene = benzene; 4b, arene = toluene). Complexes 4 were independently prepared from Cp*Ru(NO)(Me)(OTf) (5) and LiHBEt(3) in benzene with loss of CH4 and LiOTf. At 25 degrees C added naphthalene displaced the bound arene to generate Cp*Ru(NO)(eta(2)-naphthalene) (6). The crystal structure of complex 6 has been determined; it crystallized in triclinic space group P (1) over bar, with a = 8.6333(16) Angstrom, b = 9.8642(10) Angstrom, c = 11.2055(13) Angstrom, beta = 80.551(13)degrees, V = 870.6(2) Angstrom(3) and Z = 2. The ligand substitution and oxidative addition reactions of 6 with several organic substrates have been investigated. A kinetic study has shown that the reactions of 6 with phosphines, triphenylsilane, and dimethyl disulfide require initial naphthalene dissociation. The oxidative addition of diaryl disulfides also occurs, but the mechanism is more complicated. We suggest that the reaction of 6 with diaryl disulfide (aryl = Ph, p-tolyl) is catalyzed by a small concentration of a secondary product.