Thermochemistry and Reactivity of Cationic Scandium and Titanium Sulfide in the Gas Phase

Abstract

The gas-phase reactivities of the transition-metal sulfides ScS + and TiS + are investigated with guided-ion beam (GIB) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. In this work, we study the reactions of bare Sc + and Ti + ions with sulfur-transfer reagents, COS and CS 2, and of the metal sulfides, ScS + and TiS +, with oxygen-transfer substrates and with Xe to examine their collision-induced dissociation. The GIB experiments lead to several estimates for D 0 (M + −S). Further, the reaction MS + + H 2 O → MO + + H 2 S and its reverse are studied with GIB and FTICR. The equilibrium constants K eq derived from these measurements provide the most accurate values for D 0 (M + −S). Overall assessment of the results of ion−molecule reactions, collision-induced dissociations, and equilibrium measurements yields the 0 K bond dissociation energies D 0 (Sc + −S) = 4.97 ± 0.05 eV, D 0 (Ti + −S) = 4.74 ± 0.07 eV, D 0 (Sc + −CS) = 1.38 ± 0.08 eV, D 0 (Ti + −CS) = 1.60 ± 0.06 eV, and Δ f H 0 (TiOS + ) = 9.04 ± 0.18 eV.