Thermodynamic stabilities of the molecules RhUC2 and RhThC2 from Knudsen effusion mass spectrometry

Abstract

The molecules RhUC₂ and RhThC₂ have been observed in a mass spectrometric investigation of the gas phase above a thorium–uranium–rhodium–carbon system at high temperatures. Thermodynamic evaluation of the experimental data yielded the atomization energies, ΔH^°_at, ₂₉₈(RhUC₂)= 1757 ± 50 kJ mol^–1 or 420 ± 12 kcal mol^–1 and ΔH^°_at, ₂₉₈(RhThC₂)= 1774 ± 60 kJ mol^–1 or 424 ± 14 kcal mol^–1. The results, in conjunction with the bond addivity rule suggest a structure of the type Rh–M–C–C for these molecules.