Mercury-osmium carbonyl clusters resulting from facile Hg-C bond cleavage: Reactions of [Os₃H₂(CO)₁₀] with [Hg(C≡CPh)₂] and [RHgC≡CHgR] (R = Ph, Me or Et)

Reaction of the unsaturated cluster [Os3H2(CO)10] with Hg(C≡CPh)2afforded two new Os-Hg clusters cis-[Os(CO)4{(μ-Hg)Os3(CO)10(μ-η2-CH=CHPh)}2] 1 and [{Os3(CO)10(μ-η2-CH=CHPh)}2(μ4-Hg)] 2 in 30 and 20% yield, respectively. Cluster 1 consists of two (μ-Hg)Os3(CO)10(μ-η2-CH=CHPh) subunits bonded to a central Os(CO)4moiety in the cis configuration which under ambient conditions converts into 2 over 3-5 d with the extrusion of a HgOs(CO)4unit. 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-CH=CHPh)}(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 [RHgC≡CHgR] (R = Ph, Me or Et) afforded the clusters [{Os3(CO)10(μ-η2-CH=CH2)}(μ4-Hg){Os3(CO)10(μ-H)}] 6 (12%) and [{Os3(CO)10(μ-η2-CH=CH2)}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.