Isotopic studies of the metal-ligand vibrations in histamine complexes with Copper(II)

Two known copper complexes of the formulae Cu(hm)(2)(ClO4)(2), Cu(hm)Cl-2 a nd new, Cu(hm)Br-2 (hm = histamine) have been investigated in the 600-50 cm (-1) far-infrared region. Assignments of vibrations related to metal-ligand bonds have been made based on metal isotope substitution, partial deuterat ion and halogen sensitivity. Copper-hm stretching vibrations have been loca lised at 420, 417 and 411 cm(-1) for modes involving amine nitrogen and at 282, 270, 259 cm(-1) for those of imidazole nitrogen. Vibrational coupling between some metal-ligand modes has been postulated. (C) 2000 Elsevier Scie nce B.V. All rights reserved.