Mixed-metal cluster synthesis: [Re(CO)3(μ-S2NC7H4)]2 as a precursor for tri- and tetranuclear 2-mercaptobenzothiolato capped clusters

The readily prepared [Re2(CO)6(μ-S2NC7H4)2] (1) reacts with Group 8 trimetallic carbonyl clusters to yield new mixed-metal tri- and tetranuclear clusters. With [Os3(CO)10(NCMe)2] at 80 °C the tetranuclear mixed-metal cluster [Os3Re(CO)13(μ3-C7H4NS2)] (2) is the only isolated product. With Ru3(CO)12 products are dependent upon the reaction temperature. At 80 °C, a mixture of tetranuclear mixed-metal [Ru3Re(CO)13(μ3-C7H4NS2)] (5) and the triruthenium complex [Ru3(CO)9(μ-H)(μ3-C7H4NS2)] (4) results, while at 110 °C a second tetranuclear mixed-metal cluster, [Re2Ru2(CO)12(μ4-S)(μ-C7H4NS)(μ-C7H4NS2)] (3), resulting from carbon–sulfur bond scission, is the major product. Reaction of 1 With Fe3(CO)12 at 80 °C furnishes the trinuclear mixed-metal cluster [Fe2Re(CO)8(μ-CO)2(μ3-C7H4NS2)] (6). The reactivity of 6 has been probed with the aim of identifying any metal-based selectivity for carbonyl substitution. Addition of PPh3 in presence of Me3NO at 25 °C gives both the mono- and bis(phosphine)-substituted derivatives [Os3Re(CO)12(PPh3)(μ3-C7H4NS2)] (7) and [Os3Re(CO)11(PPh3)2(μ3-C7H4NS2)] (8). In 7 the PPh3 ligand occupies an axial site on wingtip osmium, while in 8 one PPh3 ligand is equatorially coordinated to wingtip osmium and the other is bonded to a hinge osmium. New complexes have been characterized by a combination of spectroscopic data and single crystal X-ray diffraction studies.