New alkyne bridged mixed-metal clusters and studies of their activity for catalytic hydrosilylation of alkynes

Richard D. Adams, Uwe Bunz, Burjor Captain, Wei Fu, Winfred Steffen

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

The homologous series of compounds MPt2(CO)5(PPh3)2(PhC2Ph), M=Fe (1), M=Ru (3) and M=Os (4) were obtained in the yields 55%, 24% and 30% from the reactions of Pt(PPh3)2(PhC2Ph) with Fe(CO)5, Ru3(CO)10, and Os(CO)5, respectively. Each of the products was characterized by IR, elemental analysis and a single crystal X-ray diffraction analysis. A second mixed-metal cluster product, Ru2Pt(CO)7(PPh3)2(PhC2Ph) (2) (45% yield) was also obtained from the reaction that yielded 3. In fact, it is obtained in a higher yield than that of 3. Compounds 1, 3, and 4 are isostructural and are comprised of a MPt2 (M=Fe, Ru or Os) triangular metal cluster containing a triply bridging diphenylacetylene ligand. The structure of compound 2 is similar to that of 1, 3, and 4, but contains two ruthenium and one platinum atom in the triangular cluster. One coproduct Os(CO)2(PPh3)2(PhC2Ph) (5) (25% yield) was obtained from the reaction of Os(CO)5 with Pt(PPh3)2(PhC2Ph). Compound 5 contains only one metal atom with an approximately trigonal bipyramidal coordination having the two phosphine ligands in the axial positions and the alkyne in an equatorial site. The reaction of 2 with H2 in refluxing hexane afforded the tetranuclear complex H2Ru2Pt2(CO)8(PPh3) 2 (6) (11% yield) that contains an Ru2Pt2 tetrahedral shaped cluster with two bridging hydride ligands. The ability of the solutions of compounds 1-6 and Pt(PPh3)2(PhC2Ph) to produce catalytic hydrosilylation of diphenylacetylene by triethylsilane to yield (E)-[(1,2-diphenyl)ethenyl]triethylsilane at 30°C, and 1,4-bis(trimethylsilyl)butadiyne with triethylsilane to yield (E)-2-triethylsilyl-1,4-bis(trimethylsilyl)-1-buten-3-yne at 60°C was investigated. Pt(PPh3)2(PhC2Ph) was the best catalyst for these reactions. Compound 5 is completely inactive. A combination of evidence suggests that the catalytic activity exhibited by the mixed-metal cluster complexes is produced principally by fragmentation products which are almost certainly mononuclear platinum complexes.

Original languageEnglish (US)
Pages (from-to)75-82
Number of pages8
JournalJournal of Organometallic Chemistry
Volume614-615
DOIs
StatePublished - Dec 8 2000
Externally publishedYes

Keywords

  • Alkyne
  • Catalysis
  • Cluster
  • Hydrosilylation
  • Platinum
  • Ruthenium

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry

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