ENTHALPIES OF REACTION OF CP'RU(COD)CL(CP'=C5H5,C(5)ME(5), COD EQUALSCYCLOOCTADIENE) WITH P(P-XC(6)H(4))(3) (X=CL, F, H, CH3, CF3,OCH3) LIGANDS - LIGAND STERIC VS ELECTRONIC CONTRIBUTIONS TO THE ENTHALPY OF REACTION

The enthalpies of reaction of Cp'Ru(COD)Cl (1; Cp' = eta(5)-C5H5, eta( 5)-C(5)Me(5); COD cyclooctadiene) with a series of para-substituted mo nodentate tertiary phosphine ligands, leading to the formation of Cp'R u(PR(3))(2)Cl, have been measured by anaerobic solution calorimetry in THF at 30.0 degrees C. These reactions are rapid and quantitative. St ructural studies have been carried out on three complexes in this seri es. The relative importance of phosphine steric vs electronic ligand p arameters is more closely examined in terms of the presented quantitat ive thermochemical and structural information. Comparisons with enthal py data in this and related organometallic systems are also presented.