A Resonance Raman, Surface-Enhanced Resonance Raman, IR, and ab Initio Vibrational Spectroscopic Study of Nickel(II) Tetraazaannulene Complexes

• Published in: Inorganic chemistry Vol. 42; no. 11; pp. 3565 - 3575
• Main Authors: Bell, Stephen, Crayston, Joe A, Dines, Trevor J, Ellahi, Saira B, Smith, Caroline I
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02.06.2003
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic026216e

The IR and resonance Raman spectra of the nickel(II) complexes of dibenzo[b,i][1,4,8,11]tetraaza[14]annulene (TAA) and 5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11]tetraaza[14]annulene (TMTAA) have been measured and compared with ab initio calculations of the vibrational wavenumbers at the B3-LYP level using the LanL2DZ basis set. An excellent fit is found between the experimental and calculated data, enabling precise vibrational assignments to be made. Surface-enhanced resonance Raman spectra were obtained following adsorption on Ag electrodes, with potentials in the range −0.1 to −1.1 V vs Ag/AgCl. There is evidence for contributions from both the electromagnetic and charge transfer (CT) surface enhancement mechanisms. The data indicate that variations in band intensities with electrode potential can be interpreted in terms of the CT mechanism.