Solvent dependences of spectral and redox properties of pyrazine (pz) complexes of ruthenium and osmium pentaammines: Ru(NH/sub 3/)/sub 5/pzCH/sub 3//sup 3 +/, Os(NH/sub 3/)/sub 5/pzCH/sub 3//sup 3 +/, and (Ru(NH/sub 3/)/sub 5/)/sup 2/pz/sup 5 +/

Journal Article · Wed Sep 09 04:00:00 EDT 1987 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00265a015· OSTI ID:6091340

Creutz, C; Chou, M H

Near-IR-vis spectra and cyclic voltammetric parameters are reported for the title compounds in the solvent series nitromethane, acetonitrile, propylene carbonate, N,N-dimethylformamide, and dimethyl sulfoxide (over which Gutmann donor number (DN) ranges from 2.7 to 29.8). As has been found in related systems, the E/sup 0/ of (NH/sub 3/)/sub 5/M/sup III/II/ decreases with donor number, with the magnitude of the response to solvent being quantitatively similar (0.025 +/- 0.002 V/DN) for all of the couples examined. (Consequently the stability of (Ru(NH/sub 3/)/sub 5/)/sub 2/pz/sup 5 +/ with respect to disproportionation is solvent independent within experimental error.) By contrast, the vis nu/sub h/) and near-IR (nu/sub 1/) absorption bands exhibit very different solvent dependences. For Ru(NH/sub 3/)/sub 5/pzCH/sub 3//sup 3 +/, the position of nu/sub h/ is solvent independent, but nu/sub 1/ exhibits a typical MLCT solvent dependence. For Os(NH/sub 3/)/sub 5/pzCH/sub 3//sup 3 +/, nu/sub 1/ shifts to longer wavelength with increasing donor number (MLCT character) while nu/sub h/ exhibits the opposite behavior. Both vis and near-IR bands of (Ru(NH/sub 3/)/sub 5/)/sub 2/pz/sup 5 +/ shift only very slightly with solvent, but the vis band of (Ru(NH/sub 3/)/sub 5/)/sub 2/pz/sup 4 +/ is more solvent dependent - about 80% as much as Ru(NH/sub 3/)/sub 5/pz/sup 2 +/. The spectral shifts are discussed in terms of a simplified molecular orbital scheme for the M-pz back-bonding interaction, and the nature of the solvent sensitivity is found to be related to the metal and pyrazine character of the MO's involved in the transition. 51 references, 5 figures, 4 tables.

• Research Organization: Brookhaven National Lab., Upton, NY
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6091340
• Journal Information: Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 26:18; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AMINES
AZINES
COMPLEXES
DATA
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
INFRARED SPECTRA
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OSMIUM COMPLEXES
PYRAZINES
RUTHENIUM COMPLEXES
SPECTRA
TRANSITION ELEMENT COMPLEXES
VISIBLE SPECTRA
VOLTAMETRY