Ruthenocenyl ruthenium bimetallic complexes:: electrospray mass spectrometric study of [RuX(η5-C5H5)(η2-dppr)]n+ (dppr=1,1′-bis(diphenylphosphino)ruthenocene) (X = Cl, n=0; X = CO, CH3CN, C=CHPh, n=1) and the X-ray crystal and molecular structure of [Ru(η5-C5H5)(CO)(η2-dppr)]PF6

[RuC1(Cp)(PPh3)(2)] (Cp = eta(5)-C5H5) reacts with dppr in refluxing benzene to give [RuC1(Cp)(dppr)], 1, {dppr =[Ru(eta(5)-C5H4PPh2)(2)]} in 91% yield. Complex 1 ionizes in boiling acetonitrile in the presence of excess NH4PF6 to give [Ru(Cp)(CH3CN)(dppr)]PF6, 2, in 76% yield. Under CO at 60 degrees C, 1 converts to [Ru(Cp)(CO)(dppr)]Cl, 3a, whose derivative [Ru(Cp)(CO)(dppr)]PF6, 3b, can also be obtained from 2 in 86% with CO. With HC=CPh, 2 instantaneously gives a vinylidene complex, [Ru(C=CHPh)(Cp)(dppr)]PF6, 4, quantitatively (98%). The kinetic stability of the eta(2)-coordinated dppr ring 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 beta = 96.21(3)degrees] reveals a pseudo-octahedral Ru(II) structure with a eta(5)-Cp, a chelated dppr, a terminal CO and an uncoordinated PF6-, anion. It is the first piano-stool dppr structure characterized by X-ray single-crystal diffractometry. The dppr chelate has a large bite (100.5(1)degrees) and there is no direct interaction between the two Ru(II) centers (Ru(l)... Ru(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 increases, fragmentation commences which inevitably gives [Ru(Cp)(dppr)](+) as the primary fragment ion. In-situ doping of dppr with AgNO3 gives [Ag(dppr)](+) as the major species plus [Ag(dppr)(2)](+) (m/z 1307) and other oxidized 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 metalloligand to give [Ag{Ru(Cp)(C=CPh)(dppr)}](+) (m/z 975) at higher voltages. Complex 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 give 52% of ethylbenzene in 5 h at 5 mol.% catalyst level. (C) 1999 Elsevier Science S.A. All rights reserved.