Experimental and theoretical studies of vanadium sulfide cation

The reactions of V+ (D-5) with CS2 and COS and the reactions of VS+ with Xe, CO, COS, CO2, and D-2 are studied as a function of translational energy in a guided-ion-beam (GIB) mass spectrometer. From these experiments, D-0(V+-S) = 3.78 +/- 0.10 eV, D-0(V+-CS) = 1.70 +/- 0.08 eV, and D-0(V+-SD) = 2.57 +/- 0.15 eV are derived. Verification of D-0(V+-S) is achieved by probing reactions of V+ and VS+ in a Fourier transform ion cyclotron resonance mass spectrometer. The good agreement between the thermochemistry obtained in the V+/CS2 system and that from the other systems studied shows that the formally spin-forbidden formation of ground-state VS+ ((3)Sigma(-)) from V+ (D-5) and CS2 has no activation barrier in excess of the reaction endothermicity. At higher energies, the spin-allowed formation of VS+ ((5)Pi) competes efficiently, giving rise to a composite shape of the VS+ cross section. The adiabatic and vertical splittings between the (3)Sigma(-) and (5)Pi states of VS+ are calculated as 1.37 and 1.87 eV at the MR-ACPF level of theory. These values agree well with the splittings obtained in GIB and sector-field mass spectrometric experiments.