The V+(NH3)(n) ions with n = 4-8 are studied by infrared (IR) photodissociation spectroscopy in the NH-stretch region with the aid of density functional theory calculations. The calculations predict a square-planar coordination of V+ for the n = 4 ion. In the IR spectra of n >= 5, red-shifted features emerge in the 3050-3300 cm(-1) region; overall spectral features agree well with those predicted for isomers with the square-planar coordination. A 6-coordinated isomer of n = 6 is computed to be more stable than the square-planar structures, but the latter are actually observed in the experiment. (C) 2012 Elsevier B.V. All rights reserved.