Thermochemical investigation of phosphine ligand substitution reactions involving trans-(PR3)2Cl2Ru=CH-CH=CPh2 complexes

Michèle E. Cucullu, Chunbang Li, Steven P. Nolan*, SonBinh T. Nguyen, Robert H. Grubbs

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The enthalpies of reaction of (PPh3)2Cl2Ru=CH-CH=CPh2 (1) with a series of tertiary phosphine ligands, leading to the formation of (PR3)2Cl2Ru=CH-CH=CPh2 complexes (PR3 = PiPr3, PBz3, PPh2Cy, PPhCy2, PCy3, and PiBu3) have been measured by solution calorimetry in CH2Cl2 at 30 °C. The range of reaction enthalpies spans some 6.5 kcal/mol and helps to establish a relative order of complex stability for these six ruthenium carbene complexes. The enthalpies of reaction for tertiary phosphine complexes, trans-(PR3)2Cl2Ru=CH-CH= CPh2, are as follows (PR3, kcal/mol): PPh3, 0; PBz3, -1.3 (0.2); PCyPh2, -1.8 (0.2); PCy2Ph, -3.8 (0.2); PiBu3, -3.8 (0.2); PiPr3, -5.2 (0.1); PCy3, -6.5 (0.3). The thermodynamics of the exchange of these sterically demanding tertiary phosphine ligands for PPh3 in 1 provides a measurement of the relative importance of phosphine steric and electronic properties/ character to the enthalpy of reaction in this system. Correlations of various factors gauging the electron-donating properties of the phosphine ligands clearly show the electronic factor to be the overwhelming contributor to the enthalpy of reaction in this system.

Original languageEnglish (US)
Pages (from-to)5565-5568
Number of pages4
Issue number25
StatePublished - 1998

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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