Resonance Raman studies in the extended near infrared region: experimental verification of a three-site mixing mechanism for valence delocalization in the Creutz-Taube ion

• Published in: Journal of the American Chemical Society Vol. 116; no. 5; pp. 2171 - 2172
• Main Authors: Petrov, Vladimir, Hupp, Joseph T, Mottley, Carolyn, Mann, Loren C
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.03.1994
• Subjects: 400102 - Chemical & Spectral Procedures; 400201 - Chemical & Physicochemical Properties; AMMONIUM COMPLEXES; Atomic and molecular physics; CHARGED PARTICLES; COMPLEXES; DEUTERIUM COMPOUNDS; ELECTROMAGNETIC RADIATION; ENERGY LEVELS; Exact sciences and technology; EXCITED STATES; HYDROGEN COMPOUNDS; INFRARED RADIATION; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; IONS; LASER SPECTROSCOPY; Molecular properties and interactions with photons; Molecular spectra; NEAR INFRARED RADIATION; Physics; RADIATIONS; Raman and rayleigh spectra (including optical scattering); RAMAN SPECTROSCOPY; RUTHENIUM COMPLEXES; SPECTROSCOPY; TRANSITION ELEMENT COMPLEXES; VALENCE; VIBRATIONAL STATES; Cationic complex; Pyrazines; Transition elements Complexes; Ammines; Dinuclear complex; Organic ligand; Ruthenium Complexes; Platinoid Complexes; Trivalent metal Complexes; Experimental study; Raman spectroscopy
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00084a078

The Creutz-Taube (C-T) ion, (NH[sub 3])[sub 5]Ru(pyrazine)Ru(NH[sub 3])[sub 5][sup 5+], was among the first intentionally prepared, molecular mixed-valency species. As a prototypical class III (i.e., electronically delocalized) system, it has been the subject of a large number of experimental, as well as theoretical, investigations. While there is now general agreement that features of the ion describe a system exhibiting both ground- and excited-state electronic delocalization, there is significantly less agreement concerning the detailed nature of the delocalization phenomenon. These more specific issues can, however, be resolved by obtaining resonance Raman spectra in the C-T intervalence region (i.e., the extended NIR). We report the first such spectra. From the spectra we find compelling evidence for a three-site mechanism for valence delocalization, necessarily involving extensive, direct bridge orbital participation. 12 refs., 1 fig.