Characterization of transition metal–rare-gas cations: VAr+ and VKr+

Resonant photodissociation of supersonically cooled and isolated VKr+ reveals a vibronic progression of a single electronic transition in the visible spectrum. Vibrational analysis of these data indicates an upper state vibrational frequency of 99 cm−1 and a diabatic upper state binding energy of 0.26 eV. Assignment of the dissociation limit of this upper state at 17 419 cm−1 to V+(3d84s 5P2)+Kr(1S0) places the adiabatic binding energy of the ground state of VKr+ at 0.49 eV. The spectrum of VAr+ is analogous to that of VKr+ but shows a somewhat reduced ground state adiabatic binding energy for this molecule, 0.38 eV. A simple inductive binding model is proposed to predict the geometries of these species and parametrize the metal–rare-gas interatomic potential. This potential is used to gain insight into the factors contributing to the enhanced stability of the ‘‘coordinatively saturated’’ complexes, VAr+4 and CoAr+6.