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-CENTER-DOT-CH2CL2

Treatment of CyRuPR(3)Cl(2) (Cy = eta(6)-cymene, p-isopropyltoluene; R = Ph or OMe) with PhMgBr gave the racemic ruthenium complexes CyRuBrP h(PPh(3)) (3) and CyRuClPh(P(OMe)(3)) (4). Reaction of 3 or 4 with AgS bF6 in the presence of 1 atm of ethylene at ambient temperature or bel ow leads to the styrene-hydride complexes [CyRuH(C(2)H(3)Ph)(PR(3))][S bF6] 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 ro tamer of each diastereomer is present in significant concentrations, a nd rotational averaging of the resonances from this process is essenti ally complete at ambient temperatures. Hydrogen exchange between the o lefin and hydride causes averaging at higher temperatures than olefin rotation and also provides a route for interconversion of the diastere omers. A significant feature of the insertion process is that the form ation of a secondary alkyl, alpha-phenethyl, is more facile than that of the primary alkyl, beta-phenethyl. An X-ray crystal structure deter mination of 5 shows a classical olefin-hydride structure rather than a n 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 = 1 5.24(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 prese nce of carbon monoxide gives [CyRu(CO)Ph(PPh(3))]SbF6 (7).