Deprotonation of Cp2Ti(SH)2 with Mononuclear Rhodium and Iridium Compounds: A New Route to Trinuclear Early−Late Heterobimetallic Complexes

Abstract

The reaction of Cp2Ti(SH)2 with [M(acac)(diolefin)] (acac = acetylacetonate) yields the complexes [Cp(acac)Ti(μ3-S)2{M(diolefin)}2] (M = Rh, diolefin = 1,5-cyclooctadiene (cod) (1); diolefin = tetrafluorobenzobarrelene (tfbb) (2); M = Ir, diolefin = cod (3)). The formation of the trinuclear heterobimetallic complexes results from a complex reaction involving the deprotonation of the hydrosulfido ligands along with the addition of the late-metal fragment(s), followed by the release of cyclopentadiene and the coordination of acetylacetonate to the titanium center. Similarly, the reaction of Cp2Ti(SH)2 with [M(quinol)(diolefin)] (quinol = 8-oxyquinolinate) gives the complexes [Cp(quinol)Ti(μ3-S)2{M(diolefin)}2] (M = Rh, diolefin = cod (4); tfbb (5); M = Ir, diolefin = cod (6)), which incorporate the 8-oxyquinolinate ligand. The d0−d8 trinuclear early−late heterobimetallic complexes exhibit triangular TiRh2 and TiIr2 cores doubly capped by two μ3-sulfido ligands. Deprotonation of Cp2Ti(SH)2 with the mononuclear carbonyl complexes [M(acac)(CO)2] (M = Rh, Ir) yields the ion-pair complexes [Cp2Ti(acac)][M3(μ3-S)2(CO)6] (M = Rh (7); M = Ir (8)), which result from complete transference of the sulfido ligands to the d8 metal centers. Carbonylation of the diolefin complexes [Cp(acac)Ti(μ3-S)2{M(diolefin)}2] or [Cp(quinol)Ti(μ3-S)2{M(diolefin)}2] yields the compounds [Cp(acac)Ti(μ3-S)2{M(CO)2}2] (M = Rh (9); M = Ir (10)) and [Cp(quinol)Ti(μ3-S)2{M(CO)2}2] (M = Rh (11); M = Ir (12)), respectively. Replacement reactions on the carbonyl complexes with triphenylphosphine give the disubstituted complexes [Cp(acac)Ti(μ3-S)2{M(CO)(PPh3)}2] (M = Rh (13); M = Ir (14)) or [Cp(quinol)Ti(μ3-S)2{M(CO)(PPh3)}2] (M = Rh (15); M = Ir (16)), which are obtained as mixtures of cis and trans isomers. The molecular structures of complexes 1 and 8 have been determined by X-ray diffraction methods.