77700-90-4Relevant articles and documents
Chemistry of the Unsaturated Cluster Compound >; X-Ray Crystal Structures of >, >, and > (Two Isomers)
Farrugia, Louis J.,Green, Michael,Hankey, David R.,Murray, Martin,Orpen, A. Guy,Stone, F. Gordon A.
, p. 177 - 190 (1985)
Reactions of the unsaturated cluster compound > with hydrogen and with diazomethane have been investigated, and the structures of the products determined by X-ray diffraction.The structure of the previously prepared carbon monoxide adduct P(cyclo-C6H11)3>> has also been established.The latter species, which is formed in a readily reversed reaction, has a 'butterfly' arrangement of the metal atoms with the platinum atom at a wing-tip position.One hydrido-ligand bridges the Os-Os vector of the body of the butterfly, and the other an Os-Pt edge.The latter is cis to the P(cyclo-C6H11)3 group on the platinum, which also carries a CO ligand.The osmium atom at the other wing-tip is ligated by four CO groups, and the remaining two Os are each terminally bonded to three carbonyls.The hydrogen adduct > is also formed reversibly but in contrast with the product from carbon monoxide has a closo-tetrahedral metal core.The hydrido-ligands occupy edge-bridging sites on the cluster framework, with two bridging Os-Pt vectors and two bridging Os-Os vectors.Thus the M4 tetrahedron has D2d symmetry with two short unbridged edges and four longer bridged edges.Diazomethane readily adds to > to give the complex > which exists as an equilibrium mixture of two isomeric forms (orange-yellow and red crystals).Both species have a closo distorted tetrahedral geometry for the metal atoms, with the methylene group bridging an Os-Os edge cisoid to the P(cyclo-C6H11)3 ligand on the platinum in the orange-yellow form and transoid to the phosphine group in the red isomer.The relative positions of the hydrido-ligands also differ.In the orange-yellow form they bridge the remaining two Os-Os edges, while although not located directly in the red isomer, being assigned on potential-energy grounds, they bridge an Os-Os edge and the Os-Pt edge cis to the P(cyclo-C6H11)3 ligand.N.m.r. studies reveal that the two isomers maintain these solid-state structures in solution.The mechanism of formation of the two isomers is discussed in the context of the orange-yellow form being the kinetically controlled product, which after several days in solution establishes a 1:4 equilibrium with the red form.
Reversible Addition of Hydrogen and Carbon Monoxide to a closo-Triosmiumplatinum Cluster: X-Ray Crystal Structures of 3Pt(μ-H)4(CO)106H11)3>> and 3Pt(μ-H)2(CO)116H11)3>>
Farrugia, Louis J.,Green, Michael,Hankey, David R.,Orpen, A. Guy,Stone, F. Gordon A.
, p. 310 - 312 (1983)
Treatment of > with either H2 or CO results in 1:1 adduct formation affording > and >, respectively, both of which revert to the starting complex under N2 purge; the structures of the adducts have been determined by X-ray crystallography, the tetrahydrido-species adopting a closo-structure and the CO complex a butterfly structure for the metal atom core.
