Ruthenocenyl ruthenium bimetallic complexes: electrospray mass spectrometric study of [RuX(eta(5)-C5H5)(eta(2)-dppr)](n+) (dppr = 1,1 '-bis(diphenylphosphino)ruthenocene) (X = Cl, n = 0; X = CO, CH3CN, C=CHPh, n = 1) and theX-ray crystal and molecular structure of [Ru(eta(5)-C5H5)(CO)(eta(2)-dppr)]PF6

[RuC1(Cp)(PPh3)(2)] (Cp = eta(5)-C5H5) reacts with dppr in refluxing benzen e to give [RuC1(Cp)(dppr)], 1, {dppr =[Ru(eta(5)-C5H4PPh2)(2)]} in 91% yiel d. Complex 1 ionizes in boiling acetonitrile in the presence of excess NH4P F6 to give [Ru(Cp)(CH3CN)(dppr)]PF6, 2, in 76% yield. Under CO at 60 degree s C, 1 converts to [Ru(Cp)(CO)(dppr)]Cl, 3a, whose derivative [Ru(Cp)(CO)(d ppr)]PF6, 3b, can also be obtained from 2 in 86% with CO. With HC=CPh, 2 in stantaneously gives a vinylidene complex, [Ru(C=CHPh)(Cp)(dppr)]PF6, 4, qua ntitatively (98%). The kinetic stability of the eta(2)-coordinated dppr rin g is evident in these reactions. The X-ray molecular structure of 3b [space group P2(1)/c, a = 9.990(2), b = 19.498(4), C = 19.113(4) Angstrom and bet a = 96.21(3)degrees] reveals a pseudo-octahedral Ru(II) structure with a et a(5)-Cp, a chelated dppr, a terminal CO and an uncoordinated PF6-, anion. I t is the first piano-stool dppr structure characterized by X-ray single-cry stal diffractometry. The dppr chelate has a large bite (100.5(1)degrees) an d there is no direct interaction between the two Ru(II) centers (Ru(l)... R u(2) 4.389 ii). The electrospray mass spectra (ESMS) of 2-4 generally give peaks due to the intact cations at low cone voltages. As the cone voltage i ncreases, fragmentation commences which inevitably gives [Ru(Cp)(dppr)](+) as the primary fragment ion. In-situ doping of dppr with AgNO3 gives [Ag(dp pr)](+) as the major species plus [Ag(dppr)(2)](+) (m/z 1307) and other oxi dized by-products. Similar treatment of 4 gives an acetylide complex [Ag{Ru (Cp)(C=CPh)(dppr)}(2)](+) (m/z 1843) at 20 V which ejects one Ru metallolig and to give [Ag{Ru(Cp)(C=CPh)(dppr)}](+) (m/z 975) at higher voltages. Comp lex 4 is hydrogenated with H-2 gas to give ethy0lbenzene in 55% yield after 4 h in refluxing THF. It also catalyzes the hydrogenation of HC=CPh to giv e 52% of ethylbenzene in 5 h at 5 mol.% catalyst level. (C) 1999 Elsevier S cience S.A. All rights reserved.