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]

Abstract

Treatment of RHgCl (R = Me, Et, Ph, Fc) with the activated cluster [Os(3)(CO)(10)(NCMe)(2)] produces the osmium-mercury mixed-metal clusters [{Os(3)(CO)(10)(andmgr;-Cl)}(2)(andmgr;(4)-Hg)] (1a) and [{Os(3)(CO)(10)(andmgr;-Cl)}(2){andmgr;-HgOs(CO)(4)}(2)] (2a) in low yields. Cluster 1a bears a central wingtip mercury atom simultaneously bridging two {Os(3)(CO)(10)(andmgr;-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){(andmgr;-Hg)Os(3)(CO)(10)(andmgr;-Cl)}(2)] (4a) via the extrusion of an Os(CO)(4) moiety under ambient conditions. Cluster 4a comprises two {(andmgr;-Hg)Os(3)(CO)(10)(andmgr;-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 Pandonemacr; with a = 9.112(2) A, b = 12.314(2) A, c = 15.501(4) A, alpha = 84.92(2), degrees beta = 88.26(3), degrees gamma = 79.52(2) degrees and Z = 2. Cluster 2a crystallizes in the triclinic space group Pandonemacr; with a = 13.306(2) A, b = 20.768(5) A, c = 9.771(4) A, alpha = 96.36(3), degrees beta = 90.50(2), degrees gamma = 98.81(2) degrees and Z = 2. Cluster 4a crystallizes in the triclinic space group Pandonemacr; with a = 18.356(2) A, b = 19.100(3) A, c = 14.478(2) A, alpha = 89.783(2), degrees beta = 113.19(2), degrees gamma = 113.70(2) degrees and Z = 4.