Investigation of the thermodynamic stabilities of the gaseous molecules RhScC, RhScC2 and RhYC2 by Knudsen effusion mass spectrometry

Abstract

The new molecules RhScC, RhScC₂ and RhYC₂ have been observed in a Knudsen effusion mass spectrometric investigation of the gaseous species over the scandium + yttrium + rhodium + graphite system in the temperature range 2318–2530 K. Thermodynamic evaluations of experimental data yielded the following atomization enthalpies: ΔH°_atm,298(RhScC)= 1010 + 40 kJ mol^–1 or 241 ± 10 kcal mol^–1, ΔH°_atm,298(RhScC₂)= 1629 ± 50 kJ mol^–1 or 389 ± 12 kcal mol^–1, ΔH°_atm,298(RhYC₂)= 1672 ± 50 kJ mol^–1 or 400 ± 12 kcal mol^–1. Suitabilities of the probable structures for these species are discussed. Data on the molecules Rh₂ and RhC₂ observed in the gas phase are also given.