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)

Abstract

Reaction of the unsaturated cluster [Os3H2(CO)10] with Hg(C[triple bond, length half m-dash]CPh)2 afforded two new Os–Hg clusters cis-[Os(CO)4{(µ-Hg)Os3(CO)10(µ-η2-CH[double bond, length half m-dash]CHPh)}2]1 and [{Os3(CO)10(µ-η2-CH[double bond, length half m-dash]CHPh)}2(µ4-Hg)]2 in 30 and 20% yield, respectively. Cluster 1 consists of two (µ-Hg)Os3(CO)10(µ-η2-CH[double bond, length half m-dash]CHPh) 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-CH[double bond, length half m-dash]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[triple bond, length half m-dash]CHgR](R = Ph, Me or Et) afforded the clusters [{Os3(CO)10(µ-η2-CH[double bond, length half m-dash]CH2)}(µ4-Hg){Os3(CO)10(µ-H)}]6(12%) and [{Os3(CO)10(µ-η2-CH[double bond, length half m-dash]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.