Vibrational and theoretical study of azabipiridyl macrocycle and its Ni(II), Cu(II) and Zn(II) complexes deposited onto a smooth copper surface

The infrared spectra of the azabipiridyl macrocycle complexes of NI(II), Cu (II) and Zn(II) were registered between 4000 and 200 cm(-1). The spectral a ssignment allowed to identify the complex formation and structural differen ces in the coordination site of the complexes. The Ni complex is coplanar t o the coordinating N atoms; the copper ion is slightly out of the coordinat ion site plane and the Zn cation is decidedly out of that plane. The stabil ity order of the complex formation Ni > Cu > Zn, is proposed. Specular refl ectance IR spectra indicated that the ligand displays an aleatory orientati on onto the smooth copper surface and the Ni and Cu complexes are oriented plane parallel to the surface. The Zn complex-surface interaction is the le ss energetic in the series. A theoretical study using the INDO/1 semiempiri cal method and a molecular model for the interacting adsorbate-substrate sy stem support quite well the experimental results and allow an interpretatio n of the energetic process of the complex-surface interaction; the energy o f the complex surface interaction follows the order Ni > Cu > Zn. (C) 2000 Elsevier Science B.V. All rights reserved.