Oxygen and Ruthenium Methylation of Ru2[(H3C)2PCH2P(CH3)2]2(CO)5. Formation and Interconversion of Terminal and Bridging Acetyl Ligands and Molecular Structure of [RU2[(H3C)2PCH2P(CH3)2] (µ-COCH3)(CO)4][CF3SO3]

Kimberly A. Johnson, Wayne L. Gladfelter

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Abstract

The reaction of Ru2(dmpm)2(CO)5, where dmpm = bis(dimethylphosphino)methane, with methyl triflate (CF3SO3CH3) results in the formation of two major products, which can be isolated by fractional crystallization. One product, obtained in 33% yield, results from methylation of the oxygen of the bridging carbonyl and contains a μ-methoxymethylidyne ligand. The structure of this compound has been determined by single-crystal X-ray crystallography (orthorhombic crystal system, Pbca space group, a = 15.325 (5) Å, b = 18.52 (1) Å, c = 20.324 (6) Å, V = 5769 (7) Å3, Z = 8). The other product, isolated in 45% yield, was formulated as [Ru2(dmpm)2(CO)5(CH3)][CF3SO3] on the basis of the mass spectrum and elemental analytical data. NMR spectroscopy shows that this complex contains a methyl group bonded directly to one Ru trans to the Ru‒Ru bond. [Ru2(dmpm)2(CO)5(CH3)][CF3SO3] was found to undergo subsequent migratory insertion to generate [Ru2(dmpm)2(CO)5[C(O)CH3]]+ and [Ru2(dmpm)2(CO)4[µ-C(O)CH3]]+. The former has a νco band at 1604 cm-1, consistent with a terminal acetyl ligand, while the latter has νco band at 1413 cm-1, similar to that for other bridging acetyl ligands. Under a CO atmosphere, the terminal acetyl is formed exclusively. The terminal acetyl can then be converted to the bridging acetyl by simply stirring the solution under nitrogen.

Original languageEnglish (US)
Pages (from-to)2101-2105
Number of pages5
JournalOrganometallics
Volume9
Issue number7
DOIs
StatePublished - Jan 1 1990

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