The spectral properties of Ru(NH3)62+ and Ru(en)32+ in aqueous solution and in several mixed solvents are reported. The higher energy absorption band of each is solvent dependent; these data are discussed in terms of a charge transfer to solvent assignment. It is shown that the diffuse model modification of the Franck-Platzman treatment of the charge transfer to solvent (c.t.t.s.) spectra of halide ions can be used with these cationic species as well. Application of this model shows that the c.t.t.s. band shifts in going from one solvent to another is more a function of the solvation energies of the oxidized and reduced species in the different solvents than of factors such as the differing Franck-Condon energies or electron solvation energies. The model also explains the lower energy of the c.t.t.s. band in the Ru(en)32+ relative to that of Ru(NH3)62+, regardless of solvent, in terms of the larger ionic radius of the former complex. In addition, the solvent studies of the Ru(NH3)62+ reveal the presence of a low extinction coefficient absorption band at 310 nm which is assigned as the 1T2g ← 1A1g ligand field transition. Calculations based on the energy of this band plus the 1T1g ← 1A1g band at 390 nm give the crystal field parameters Δ = 26.8 × 103 cm -1 and B = 454 cm-1 for Ru(NH3) 62+.
|Number of pages||11|
|Journal||Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics|
|State||Published - 1 Dec 1979|
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry