GENERAL-ROUTE TO THE HALF-OPEN METALLOCENES C5ME5RU(PENTADIENYL) AND C5ME5RU(DIENE)CL - X-RAY STRUCTURES OF AN OPTICALLY-ACTIVE HALF-OPEN METALLOCENE AND OF A DIMETALLIC RUTHENABENZENE COMPLEX

Treatment of [C5Me5RuCl2]n (1) with various acyclic and cyclic diolefins in the presence of zinc powder leads to the "half-open"; metallocenes C5Me5Ru(pentadienyl), to C5Me5Ru(diolefin) chloro compounds, or to cationic complexes with an eta-6 ligand, depending on the stereochemistry and substitution pattern of the starting diolefin. An X-ray crystallographic analysis of optically active C5Me5Ru(dimethylnopadienyl) (11; [alpha]589 = -250.6-degrees), which crystallizes from methanol in the monoclinic space group P2, with a = 9.214 (4) angstrom, b = 17.593 (8) angstrom, c = 13.115 (6) angstrom, beta = 101.55 (4)-degrees, and Z = 4, reveals the coordination of the C5Me5Ru moiety from the sterically less hindered side of the tricyclic ligand. The half-open metallocene C5Me5Ru(2,4-C7H11) (2; 2,4-C7H11 = eta-5-2,4-dimethylpentadienyl) can be protonated with HBF4, yielding [C5Me5Ru(H)(C7H11)]BF4, which has a dynamic structure on the NMR time scale. 2 can also be lithiated; the site of lithiation could be determined by quenching experiments with MeOD/CH3COOD. 2 reacts with [C5H5Ru(CH3CN)3]PF6 to yield the dimetallic complex [C5H5Ru(mu-2,4-C7H9)Ru(C5Me5)(CH3CN)]PF6 (19). 19 crystallizes from propionic anhydride in the orthorhombic space group Pnma, with a = 13.274 (2) angstrom, b = 11.865 (2) angstrom, c = 16.578 (3) angstrom, and Z = 4 and displays an eta-6 coordination of a ruthenabenzene unit to C5H5Ru. The substitution of the diolefin and/or chloro ligand in C5Me5Ru(2-methyl-(E)-pentadiene)Cl (7) in a range of solvents and under mild conditions is a rapid and facile process. Mono- and bidentate ligands (Br, CO, CH3, P(OMe)3, cod) substitute the diolefin, the chloro ligand, or both, depending on reaction conditions, to produce the complex C5Me5RuL2X, [C5Me5RuL3]+ or [C5Me5RuL2L']+. All compounds are obtained in high yield and have been characterized by a combination of elemental analyses and spectroscopic methods (IR, H-1 and C-13 NMR, MS).