Far-infrared spectra of histamine (hm) complexes [Pd(hm)(2)]Cl-2, and [Pd(hm)Cl-2] have been interpreted based on metal isotope substitution, partial deuteration and halogen exchange. Stretching vibrations of palladium(II)-histamine bonds have been detected at 464 and 372 cm(-1) for Pd-NH2, and at 311 cm(-1) for Pd-N (imidazole), Palladium(II)-halogen modes have been located at 326 and 311cm(-1) for chloro complex and at 205 and 198 cm(-1) for the bromo analogue, respectively. (C) 2000 Elsevier Science B.V, All rights reserved.