Synthesis and thermochemistry of HMo(CO)3C5Me5; Comparison of cyclopentadienyl and pentamethylcyclopentadienyl ligands

Steven P. Nolan, Carl D. Hoff, John T. Landrum

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74 Scopus citations


Toluenemolybdenum tricarbonyl reacts quantitatively with pentamethylcyclopentadiene in THF at room temperature yielding HMo(CO)3C5Me5. The heat given off in this reaction has been measured by solution calorimetry and indicates there is little difference in the MoC5H5 and MoC5Me5 bond strengths. Thermochemical measurements of the reaction of HMo(CO)3C5R5 (R = H, CH3) with pyridine yielding (py)3Mo(CO)3 confirm this result. In THF solution, HMo(CO)3C5Me5 is a weaker acid than HMo(CO)3C5H5, ΔpKa ≥ 3. The heat of hydrogenation of (Mo(CO)3C5R5)2 to yield two mol of HMo(CO)3C5R5 is more favorable by about 2 kcal/mol for R = CH3 compared to R = H, probably due to steric repulsion in (Mo(CO)3C5Me5)2.

Original languageEnglish (US)
Pages (from-to)357-362
Number of pages6
JournalJournal of Organometallic Chemistry
Issue number3
StatePublished - Mar 12 1985

ASJC Scopus subject areas

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


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