New Mixed‐Metal Carbonyl Complexes Containing Bridging 2‐Mercapto‐1‐methylimidazole Ligand

Abstract

AbstractReaction of [Mn2(CO)10] with 2‐mercapto‐1‐methylimidazole in the presence of Me3NO at 25 °C afforded two new dimanganese complexes [Mn2(CO)6(μ‐SN2C4H5)2] (1) and [Mn2(CO)7(μ‐SN2C4H5)2] (2). Compound 1 consists of two μ‐SN2C4H5 ligands, each bound through the sulfur atom to two Mn atoms and through the nitrogen atom to one Mn atom forming a four‐membered chelate ring. Compound 2 was found to consist of one μ‐SN2C4H5 ligand in a similar bonding mode to 1 but another μ‐SN2C4H5 ligand coordinates through the sulfur atom to one Mn atom and through the nitrogen atom to another Mn atom. Compound 1 was also obtained as the only product from the reaction of [Mn2(CO)8(NCMe)2] with 2‐mercapto‐1‐methylimidazole. In contrast, a similar reaction of [Re2(CO)8(NCMe)2] with 2‐mercapto‐1‐methylimidazole led to the formation of the di‐, tri‐, and tetranuclear complexes [Re3(CO)8(μ‐CO)(μ3‐SN2C4H5)2(μ‐H)] (3), [Re4(CO)12(μ‐SN2C4H5)4] (4), and [Re2(CO)6(μ‐SN2C4H5)2] (5). Compound 3 provides a unique example of a hydrido trirhenium compound. The reaction of [Cr(CO)3(NCMe)3] and [Mo(CO)3(NCMe)3] with 1 in refluxing THF afforded the mixed metal complexes [CrMn2(CO)8(μ‐CO)2(μ3‐SN2C4H5)2] (6) and [MoMn2(CO)8(μ‐CO)2(μ3‐SN2C4H5)2] (7), respectively, in which two Mn–M (M = Mo, Cr) bonds were formed. In contrast, a similar treatment of [W(CO)3(NCMe)3] with 1 yielded two W‐Mn complexes [Mn2W(CO)8(μ‐CO)2(μ3‐SN2C4H5)2] (8) and [Mn2W(CO)7(μ‐CO)2(SN2C4H5)(μ3‐SN2C4H5)2] (9). Treatment of 1 with [Fe3(CO)12] at 70‐75 °C afforded the trinuclear mixed‐metal complex [FeMn2(CO)8(μ‐CO)(μ3‐SN2C4H5)2] (10) and the diiron side product [Fe2(CO)6(μ‐S2N2C4H5)2] (11). Compounds 6‐10 have a bent open structure of three metal atoms linked by two metal‐metal bonds and all, except 9 and 10, contain a noncrystallographic two‐fold axis of symmetry. Compound 9 is structurally similar to 8, but it contains a SN2C4H6 ligand, mono coordinated through the exocyclic sulfur atom to the W atom and a Mn–Mn bond instead of a Mn–W bond. Compound 11 comprises two bridging S2N2C4H5 ligands, which arise from the coupling of 2‐mercapto‐1‐methylimidazole with sulfur.