Comparison of metal-hydrogen, -oxygen, -nitrogen and -carbon bond strengths and evaluation of functional group additivity principles for organoruthenium and organoplatinum compounds

Abstract

The equilibria: L n MX + HY ⇁ L n MY + HX (L n M = (DPPE)MePt or Cp(PMe 3) 2Ru; X, Y = hydride, alkoxide, hydroxide, amide, alkyl, alkynyl, hydrosulphide, cyanide) have been examined. The equilibrium constants allow for the determination of relative MX, MY bond dissociation energies (BDEs) for each series of compounds. A linear correlation of L n MX to HX BDEs is found for the two dissimilar metal centres. Activation barriers for phosphine dissociation from Cp(PMe 3) 2RuX complexes have been measured and suggest the principle of functional group additivity has limited applicability in organometallic thermochemistry. The generality and predictive value of this correlation and the observations on functional group additivity are discussed.