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.