ORGANORUTHENIUM THERMOCHEMISTRY - ENTHALPIES OF REACTION OF CP'RU(COD)CL (CP'=ETA(5)-C5H5 AND ETA(5)-C(5)ME(5)) WITH TERTIARY PHOSPHITE LIGANDS

The enthalpies of reaction of Cp'Ru(COD)Cl (Cp' = eta(5)-C5H5 (Cp), et a(5)-C(5)Me(5) (Cp); COD = cyclooctadiene) with a series of monodenta te phosphite ligands, leading to the formation of Cp'Ru(P(OR)(3))(2)Cl , have been measured by anaerobic solution calorimetry in THF at 30 de grees C. The overall relative order of stability established for the p receding complexes is as follows: for the CpRu(P(OR)(3))(2)Cl series, P(O-o-MeC(6)H(4))(3) < P(OC6H5)(3) < P((OPr)-Pr-i)(3) < P(OCH2)(3)CEt < P(OMe)(3); for the CpRu(P(OR)(3))(2)Cl series, P(O-o-MeC(6)H(4))(3) < P(OC6H5)(3) < P(OCH2)(3)CEt < P((OPr)-Pr-i)(3) < P(OMe)(3). Single- crystal diffraction studies were carried out on two members of the Cp Ru(P(OR)(3))(2)Cl series, P(OR)(3) = P(OMe)(3) and P(OR)(3) = P(OCH2)( 3)CEt (TMPP). Comparisons with other organometallic systems and insigh t into factors influencing the Ru-P(OR)(3) bond disruption enthalpies are discussed.