Penta- and hexa-nuclear ruthenium µ-2-pyridyl complexes

Abstract

The ruthenium(II) pyridine-2-thionato (pyS) complex [Ru(pyS)2(CO)2]1 reacts with [Ru3(CO)12] in a sealed glass tube under vacuum to give the chain compounds [Ru6(µ4-S)2(µ-C5H4N)2(CO)18]2(38%) and [Ru4(µ4-S)(µ-C5H4N)2(CO)12]3(23%)(C5H4N = 2-pyridyl). The crystal structure of 2 shows it to contain three Ru2 units linked into a chain by tetrahedral µ4-sulfur atom bridges and with the terminal Ru2 units co-ordinated to µ-C5H4N ligands. Isomerism in compounds 2 and 3 results from the different geometries of attachment of the µ-C5H4N ligands. If the reaction of 1 with [Ru3(CO)12] is alternatively carried out in refluxing xylene under nitrogen so that CO can escape there is considerable decomposition but a compound with lower CO content, [Ru5(µ4-S)2(µ-C5H4N)2(CO)11]4, is formed in low yield (15%). The crystal structure shows that cluster 4 contains five Ru–Ru bonds within a Ru5S2 pentagonal bipyramidal unit with two axial Ru atoms liked by non-disordered µ-C5H4N bridges to Ru atoms in the equatorial plane. The µ4-S atoms are pyramidal rather than tetrahedral.