The geometries, energies, and vibrational frequencies of various isomers of XO(4)(m-)(H(2)O), x = Cl, Br, Se, As, V; n = 0-6, m = 1-3 are calculated at various levels up to MP2/6-31+G*. These properties are studied as a function of increasing cluster size. The experimental and theoretical vibrational spectra are compared where available.