Gaseous Ruthenium Research Articles

High temperature chemistry of the gaseous ruthenium fluorides

Mass spectrometry was used to identify and to thermochemically characterize the gaseous fluorides RuF4 , RuF3 , RuF2 , and RuF generated by fluorination of Ru powder in a platinum effusion cell. Reaction enthalpies and bond dissociation energies were derived from equilibrium measurements involving these species, yielding the following results in kJ mol−1 : D°(F3 Ru–F)=361; D°(F2 Ru–F)=339; D°(FRu–F)=464; and D°(Ru–F)=402. The results show that the +4 oxidation state dominates the high temperature chemistry of the Ru–F system. Results are compared with the properties of the neighboring Mo–F system.

THERMODYNAMIC PROPERTIES OF GASEOUS RUTHENIUM CHLORIDES AT HIGH TEMPERATURE1

The thermodynamic properties of the gaseous ruthenium chlorides were studied over the range 650 to 1500 deg and at chlorine pressures from 0.1 to 1.5 atm. The effect of chlorine pressure on vapor pressure indicates that the important vapor species are RuCl/sub 4/ and RuCl/sub 3/. Over RuCl/sub 3/( s) at a chlorine pressure of 1 atm., RuCl/sub 4/(g) is the principal species, reaching a maximum partial pressure of 0.065 atm. at 853 deg --the temperature at which RuCl/sub 3/(s) decomposes. Above 853 deg , where Ru(s) is the stable condensed phase, the partial pressure of RuCl/sub 4/(g) decreases with increasing temperature, and RuCl/sub 3/(g) becomes the principal species. At 1500 deg , the partial pressure of RuCl/sub 3/(g) in equilibrium with Ru(s) and 1-atm. Cl/sub 2/ is 0.16 atm. Thermodynamic quantities were determined for the reactions and species studied. (auth)