Organoruthenium Thermochemistry. Enthalpies of Reaction of Cp‘Ru(COD)Cl (Cp‘ = η5-C5H5 and η5-C5Me5) with Tertiary Phosphite Ligands

Abstract

The enthalpies of reaction of Cp‘Ru(COD)Cl (Cp‘ = η5-C5H5 (Cp), η5-C5Me5 (Cp*); COD = cyclooctadiene) with a series of monodentate phosphite ligands, leading to the formation of Cp‘Ru(P(OR)3)2Cl, have been measured by anaerobic solution calorimetry in THF at 30 °C. The overall relative order of stability established for the preceding complexes is as follows: for the CpRu(P(OR)3)2Cl series, P(O-o-MeC6H4)3 < P(OC6H5)3 < P(OiPr)3 < P(OCH2)3CEt < P(OMe)3; for the Cp*Ru(P(OR)3)2Cl series, P(O-o-MeC6H4)3 < P(OC6H5)3 < P(OCH2)3CEt < P(OiPr)3 < P(OMe)3. Single-crystal diffraction studies were carried out on two members of the Cp*Ru(P(OR)3)2Cl series, P(OR)3 = P(OMe)3 and P(OR)3 = P(OCH2)3CEt (TMPP). Comparisons with other organometallic systems and insight into factors influencing the Ru−P(OR)3 bond disruption enthalpies are discussed.