Chemistry of the Metal Carbonyls. Part 76. Platinum-Osmium Carbonyl Complexes derived from Decacarbonyldi-μ-hydrido-triosmium; X-Ray Crystal Structure of >

Article abstract of DOI:10.1039/DT9810000155

Reactions between and the compounds afford tetranuclear metal complexes .Examination of the variable-temperature 1H n.m.r. spectra of these '58-electron' clusters reveals dynamic behaviour with site exchange of the two hydrido-ligands, the energy barrier for this process for the P-t-Bu2Me derivative being ca 58 kJ mol^-1.In order to establish the molecular structure of these complexes a single-crystal X-ray diffraction study was made on the compound containing the P(cyclo-C6H11)3 ligand.Crystals are monoclinic, space group P2₁/Z = 4, in a unit cell of dimensions a=11.822(4), b=16.584(5), c=17.763(9) Angstroem, and β=108.10(4) deg.The structure has been refined to R 0.035 (R' 0.038) for 5 737 refletions to 20 < 60 deg (Mo-K_α, X-radiation) collected at 200 K.The metal atoms adopt a slightly asymmetric tetrahedral structure The platinum atom is bonded to a CO group and to the P(cyclo-C6H11)3 ligand, and each osmium attached to three CO groups.The hydrido-ligands bridge the longer of the Os-Os and Os-Pt bonds, as deduced from observation of residual electron densities, from widening of certain Pt-Os-CO and Os-Os-Co angles, from staggered conformations of two of the Os(CO)3 groups with respect to the two longer edges of the tetrahedron, and from calculation of potential energy minima.

Full text of DOI:10.1039/DT9810000155

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