Ru-Sn and Ru-Os mixed-metal clusters bearing heterocyclic thiolate ligand(s): Synthesis, crystal and electronic structures

Abstract

The synthesis of [Ru2(CO)4(SnMe3)2(µ-L)2] (1–2) (1, L = pySH = pyridine-2-thiol; 2, L = pymSH = pyrimidine-2-thiol) and their reactions with [M3(CO)10-n(NCMe)n] (M = Ru, Os; n = 0, 2) are described. Ru2Sn2 clusters are prepared in moderate yields from the one-pot reaction of [Ru3(CO)12], Me3SnCl and pySH in the presence of KOH, and each contains two [Ru(CO)2(SnPh3)] units bridged by a pair of heterocyclic thiolate ligands. Treatment of 1–2 with [Ru3(CO)12] in boiling benzene affords pentaruthenium clusters [Ru5(CO)16(µ3-L)(µ4-SnMe)] (3–4) containing a raft-like metallic core consisting of five ruthenium and one tin atom. In contrast, reactions of 1–2 with [Os3(CO)10(NCMe)2] yield tetranuclear clusters [RuOs3(CO)12(η1-Me)(µ3-L)] (5, L = pyS; 7, L = pymS) as the major products, in which the four metal atoms adopt a butterfly geometry, with the ruthenium occupying a wingtip position. Further products including [RuOs3(CO)12(µ3-pyS)(µ-H)] (6) and [Os4(CO)12(µ3-pymS)(η1-Me)] (8) are also isolated from these reactions. Clusters 6 and 8 possess an M4 butterfly skeleton, with ruthenium in a hinge position in mixed-metal cluster 6. The molecular structure of each product has been established by XRD analysis, and the bonding in these clusters has been investigated by electronic structure calculations.