Derivative Chemistry of [Ru2(μ-bdt)(CO)6], a Binuclear Ruthenium(I) Carbonyl Complex Containing a Bridging Benzene-1,2-dithiolate Ligand

Abstract

The known dithiolate-bridged ruthenium(I) complex [Ru2(μ-bdt)(CO)6] (1) (bdt = benzene-1,2-dithiolate) has been prepared in fair yield (55%) by the sequential treatment of RuCl3·nH2O with carbon monoxide, benzene-1,2-dithiol and zinc in a one-pot reaction. Complex 1 reacts readily with monodentate phosphanes to give, stepwise, the penta- and tetracarbonyl derivatives [Ru2(μ-bdt)(CO)6–n(PR3)n] (n = 1, 2; R = Ph, Cy, iPr). However, the reaction of 1 with one equivalent of bis(diphenylphosphanyl)methane (dppm) affords a mixture of complex 1 and the disubstituted derivative [Ru2(μ-bdt)(CO)4(η1-dppm)2], in which the dppm ligands are monodentate. This mixture is subsequently transformed into a polymeric material of formula [{Ru2(μ-bdt)(CO)4}(μ-dppm)]n, which consists of binuclear {Ru2(μ-bdt)(CO)4} units linked to each other by bridging dppm ligands. The use of two equivalents of dppm leads to [Ru2(μ-bdt)(CO)4(η1-dppm)2] in quantitative yield. The X-ray diffraction structure of [Ru2(μ-bdt)(CO)4(PiPr3)2] (3c) confirms that the phosphane ligands are located in axial positions, cis to both sulfur atoms, and that the Ru–Ru distance is short [2.6753(7) Å]. A comparative study of the reactivity of complexes 1 and 3c with the electrophiles H+, [Au(PPh3)]+, and HgCl2 has allowed the isolation of the derivatives [Ru2(μ-H)(μ-bdt)(CO)6–n(PiPr3)n][BF4] (n = 0, 2), [Ru2Au(μ-bdt)(CO)6–n(PiPr3)n(PPh3)][BF4] (n = 0, 2) and [Ru2HgCl2(μ-bdt)(CO)6–n(PiPr3)n] (n = 0, 2), respectively.