Synthesis and Structures of four Mono(organo)phosphido-bridged pentaruthenium carbonyl Clusters, [Ru 5(CO) 15(μ 4-PR)] (RC 6H 5, CH 3,CH 2CH 3 and CH 2C 6H 5

Abstract

The reactions of [(C 5H 5)(CO) 2MnPRCl 2] (RC 6H 5, CH 3, CH 2CH 3 and CH 2C 6H 5) with Ru 3(CO) 12 yield clusters of the type [Ru 5(CO) 15PR] in which the phosphorus atom is pentacoordinated and bonded to four ruthenium atoms. The compounds have been studied by 31P NMR spectroscopy and their structures have been determined by X-ray crystallography. The compound [Ru 5(CO) 15PC 6H 5] crystallises in space group P 1 with a=9.543(9) Å, b= 9.560(7) Å, c=29.63(4) Å, β= 89.78(9)° and Z=4. The structure was solved by direct methods (SHELXTL) and refined by full matrix refinements (Syntex-EXTL System) to a final R value of 0.061 for 2810 independent significant data. The molecular structures of the two independent molecules within the asymmetric unit are nearly identical. The overall molecular geometry is that of a distorted octahedron. The average Ru—Ru, Ru—P and Ru—C distances are 2.852 Å, 2.372 Å and 1.890 Å, respectively. The compound [Ru 5(CO) 15PCH 2CH 3] crystallises in space group Cc with a=15.77(2) Å, b= 9.917(6) Å, c=19.64(2) Å,β=124.32(6)° and Z=4. The structure was solved and refined by similar procedures as described for the previous compound to a final R value of 0.046 for 1289 observed data. The overall geometry is that of a distorted octahedron. The average Ru—Ru, Ru—P and Ru—C distances are 2.849 Å, 2.371 Å and 1.885 Å, respectively. The structure of the clusters can be described as square-pyramidal with five ruthenium atoms and the phosphide ligand capping the square face.