Mercury–osmium carbonyl clusters resulting from facile Hg–C bond cleavage: reactions of [Os3H2(CO)10] with [Hg(CCPh)2] and [RHgCCHgR](R = Ph, Me or Et)

Abstract

Reaction of the unsaturated cluster [Os₃H₂(CO)₁₀] with Hg(CCPh)₂ afforded two new Os–Hg clusters cis-[Os(CO)₄{(µ-Hg)Os₃(CO)₁₀(µ-η²-CHCHPh)}₂]1 and [{Os₃(CO)₁₀(µ-η²-CHCHPh)}₂(µ₄-Hg)]2 in 30 and 20% yield, respectively. Cluster 1 consists of two (µ-Hg)Os₃(CO)₁₀(µ-η²-CHCHPh) subunits bonded to a central Os(CO)₄ moiety in the cis configuration which under ambient conditions converts into 2 over 3–5 d with the extrusion of a HgOs(CO)₄ unit. Cluster 2 comprises two skewed Os–Hg metal butterflies sharing a common wingtip Hg atom. In refluxing tetrahydrofuran (66 °C)2 underwent redistribution with the symmetrical mercurials [Hg{M(CO)₃(η⁵-C₅H₅)}₂](M = Cr, Mo or W) to afford respectively the heterometallic clusters [{Os₃(CO)₁₀(µ-η²-CHCHPh)}(µ₃-Hg){M(CO)₃(η⁵-C₅H₅)}](M = Cr 3, Mo 4 or W 5) in moderate yield. Alternatively, 3–5 can be obtained more readily from the reaction of cluster 1 with the corresponding symmetric mercurials at room temperature. Reactions of [Os₃H₂(CO)₁₀] with [RHgCCHgR](R = Ph, Me or Et) afforded the clusters [{Os₃(CO)₁₀(µ-η²-CHCH₂)}(µ₄-Hg){Os₃(CO)₁₀(µ-H)}]6(12%) and [{Os₃(CO)₁₀(µ-η²-CHCH₂)}₂(µ₄-Hg)]7(25%). Cluster 7 is isostructural with 2, whilst 6 bears a central Hg atom connecting two structurally different osmium triangles. Clusters 1, 2, 6 and 7 all result from Hg–C bond cleavage of the parent organomercury species, hence the generality of this cleavage is demonstrated. The new clusters 1, 2, 4, 6 and 7 have been fully characterised by both spectroscopic and crystallographic techniques.