Diruthenium tetracarbonyl complexes of sawhorse-type

The reaction of [Ru3(CO)12] with pivalic acid in acetonitrile afforded the coordinatively unsaturated complex [{Ru2(μ-O2CtBu)2(CO)4}n] (1) for which a so far unknown polymeric structure is assumed. Compound 1 showed in the solid as well as dissolved in non-polar aliphatic solvents and carbon tetrachloride, respectively, a deep violet color. In common organic solvents 1 is readily dissolved resulting in solutions exhibiting a yellow to orange color. On the one hand, in such solutions the polymeric structure of 1 is broken resulting in distinct compounds as the Ru2(μ-O2CtBu)2(CO)4 units coordinate two monodentate solvent molecules, as shown for [Ru2(μ-O2CtBu)2(CO)4(py)2] (3, py = pyridine), or they coordinate ligands like phosphanes, as shown for [Ru2(μ-O2CtBu)2(CO)4(PtBu2H)2] (4). On the other hand, in solutions of 1 the Ru2 frameworks are linked by coordination of multidentate solvent molecules resulting in a coordination polymer which was confirmed by the crystal structure determination of [{Ru2(μ-O2CtBu)2(CO)4(HOC2H4OEt)}n] (2).