The importance of cluster fragmentation in the catalytic hydrogenation of phenylacetylene by PtRu5 carbonyl cluster complexes

Richard D. Adams, Burjor Captain, Lei Zhu

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

PtRu5 (CO)13 (PBu3t) (μ3 - PhC2 H) (μ5 - C) (2) has been shown to be a catalyst precursor for the hydrogenation of PhC2H to styrene and ethylbenzene. Three new organometallic products have been found in the catalyst solutions. These are Ru5 (CO)125 - C) [PtPBu3t] (μ3 - PhC2 H) (μ - H)2 (4), Pt (PBu3t) (PhC2 H) (CO) (5), and Ru5(CO)114-CCHCPh)(μ4-HC2Ph)(μ3-HC2Ph) (6). Compounds 4-6 have been synthesized independently and structurally characterized and each one has been tested independently for its ability to produce hydrogenation of PhC2H catalytically. Compound 4 contains an open square-pyramidal cluster of five ruthenium atoms with one platinum atom bridging an edge of the cluster. It is structurally related to 2 but contains one less CO ligand and two hydrido ligands formed by the addition of one equivalent of hydrogen to the metal cluster. It can be obtained directly from 2 by reaction with hydrogen in the presence of trimethylamine oxide. Compound 5 is a tricoordinated mononuclear platinum complex containing one PBu3t ligand, one CO ligand and one μ2-PhC2H ligand. Compound 5 can be obtained directly from Pt (PBu3t)2 by reaction with PhC2H under an atmosphere of CO. Compound 6 was obtained from the reaction of Ru5(CO)155-C) with PhC2H in the presence of UV-Vis irradiation. Compound 6 contains three equivalents of PhC2H; one is present as triply bridging PhC2H ligand; one is a quadruply bridging ligand; the third one has formed a bond to the carbido ligand in the center of the metal cluster to form a novel tetra-metallated allyl ligand. Compound 5 has the highest catalytic activity of all three compounds and is believed to be responsible for the vast majority of the catalytic hydrogenation produced from the solutions of 2. Compound 4 is transformed into 5 under the conditions of catalysis.

Original languageEnglish (US)
Pages (from-to)3122-3128
Number of pages7
JournalJournal of Organometallic Chemistry
Volume691
Issue number14
DOIs
StatePublished - Jul 1 2006
Externally publishedYes

Keywords

  • Cluster fragmentation
  • Hydrogenation
  • Platinum
  • Ruthenium

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Materials Science (miscellaneous)
  • Materials Chemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Biochemistry

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