ETHYLENE INSERTION INTO A RUTHENIUM-PHENYL BOND OF A CHIRAL LEWIS-ACID - A FACILE METHOD OF PREPARING OLEFIN-HYDRIDE COMPLEXES - CRYSTAL-STRUCTURE OF [CYRUH(C(2)H(3)PH)(PPH(3))]SBF6.CH2CL2

Treatment of CyRuPR(3)Cl(2) (Cy = eta(6)-cymene, p-isopropyltoluene; R = Ph or OMe) with PhMgBr gave the racemic ruthenium complexes CyRuBrPh(PPh(3)) (3) and CyRuClPh(P(OMe)(3)) (4). Reaction of 3 or 4 with AgSbF6 in the presence of 1 atm of ethylene at ambient temperature or below leads to the styrene-hydride complexes [CyRuH(C(2)H(3)Ph)(PR(3))][SbF6] 5 (R = Ph) and 6 (R OMe). NMR and chemical studies of both 5 and 6 showed that they exist as two diastereomers in solution. Only one rotamer of each diastereomer is present in significant concentrations, and rotational averaging of the resonances from this process is essentially complete at ambient temperatures. Hydrogen exchange between the olefin and hydride causes averaging at higher temperatures than olefin rotation and also provides a route for interconversion of the diastereomers. A significant feature of the insertion process is that the formation of a secondary alkyl, alpha-phenethyl, is more facile than that of the primary alkyl, beta-phenethyl. An X-ray crystal structure determination of 5 shows a classical olefin-hydride structure rather than an agostic Ru-H-C interaction. Racemic 5 crystallizes in the monoclinic space group P2(1)/n with cell parameters of a = 10.49 Angstrom, b = 15.24(1) Angstrom, c = 24.015(4) Angstrom, beta = 101.94(3)degrees, V = 3755(9) Angstrom(3), Z = 4 The reaction of 3 with AgSbF6 in the presence of carbon monoxide gives [CyRu(CO)Ph(PPh(3))]SbF6 (7).