Mass spectrometric evidence for the very high stability of diatomic cerium compounds with some platinum metals and predicted dissociation energies of selected diatomic intermetallic compounds with multiple bonds

Abstract

The molecules CeRh, CeIr and CePt have been identified by means of Knudsen cell mass spectrometry and their dissociation energies determined as D^°₀(CeRh)= 130.4 ± 6.0; D°₀(CeIr)= 138.8 ± 6.0; and D°₀(CePt)= 131.7 ± 6.0 kcal mol^–1(545.6, 580.7, and 551.0 ± 25 kJ mol^–1). The remarkably high stability of these molecules is interpreted in terms of multiple bond formation.

A previously proposed method (K. A. Gingerich, Chem. Phys. Letters, 1973, 23, 270) is illustrated for the calculation of dissociation energies of second transition period intermetallic molecules which are expected to have multiple bonds. Dissociation energies of diatomic cerium and lanthanum compounds with platinum metals have also been calculated by this method and are compared with available experimental values.