Phosphorus sulfide cages alpha-P(4)S(4), alpha-P(4)S(5), beta-P(4)S(5), and beta-P(4)S(6) and transition-metal chlorides TaCl(5) and NbCl(5) form molecular adducts in CS(2)/n-hexane. The crystal structures of the adducts (TaCl(5))(alpha-P(4)S(4)), (TaCl(5))(alpha-P(4)S(5)), (TaCl(5))(beta-P(4)S(5)), (NbCl(5))(beta-P(4)S(5)), and (TaCl(5))(beta-P(4)S(6)) are reported and their conformation and energetic stability are discussed on the basis of ab initio electronic structure calculations. Furthermore bond lengths of coordinated and noncoordinated phosphorus sulfide cages obtained from experiment and theory are compared, emphasizing the changes within the cages that emerge upon coordination.