Heterometallic Osmium−Mercury Chain Structures Linking Two {Os₃(CO)₁₀(μ-X)} Subunits (X = Cl, Br, I):  Syntheses and Molecular Structures of [{Os₃(CO)₁₀(μ-X)}₂(μ₄-Hg)] (X = Cl, I), [{Os₃(CO)₁₀(μ-Cl)}₂{μ-HgOs(CO)₄}₂], and cis-[Os(CO)₄{(μ-Hg)Os₃(CO)₁₀(μ-Cl)}₂]

Treatment of RHgCl (R = Me, Et, Ph, Fc) with the activated cluster [Os₃(CO)₁₀(NCMe)₂] produces the osmium−mercury mixed-metal clusters [{Os₃(CO)₁₀(μ-Cl)}₂(μ₄-Hg)] (1a) and [{Os₃(CO)₁₀(μ-Cl)}₂{μ-HgOs(CO)₄}₂] (2a) in low yields. Cluster 1a bears a central wingtip mercury atom simultaneously bridging two {Os₃(CO)₁₀(μ-Cl)} units. Cluster 2a comprises an unprecedented decanuclear osmium−mercury framework in which there is a central linear “Hg−{Os(CO)₄}₂−Hg” molecular backbone with the two Os(CO)₄ fragments arranged in a staggered conformation. Cluster 2a is thermally unstable and converts slowly to cis-[Os(CO)₄{(μ-Hg)Os₃(CO)₁₀(μ-Cl)}₂] (4a) via the extrusion of an Os(CO)₄ moiety under ambient conditions. Cluster 4a comprises two {(μ-Hg)Os₃(CO)₁₀(μ-Cl)} subcluster units bonded to a central Os(CO)₄ moiety in a cis configuration. Similar reactions with PhHgBr and MeHgI have also been investigated. Cluster 1a crystallizes in the triclinic space group P1̄ with a = 9.112(2) Å, b = 12.314(2) Å, c = 15.501(4) Å, α = 84.92(2),° β = 88.26(3),° γ = 79.52(2)° and Z = 2. Cluster 2a crystallizes in the triclinic space group P1̄ with a = 13.306(2) Å, b = 20.768(5) Å, c = 9.771(4) Å, α = 96.36(3),° β = 90.50(2),° γ = 98.81(2)° and Z = 2. Cluster 4a crystallizes in the triclinic space group P1̄ with a = 18.356(2) Å, b = 19.100(3) Å, c = 14.478(2) Å, α = 89.783(2),° β = 113.19(2),° γ = 113.70(2)° and Z = 4.