Solvent-induced and polyether-ligand-induced redox isomerization within an asymmetrically coordinated mixed-valence ion: trans-(py)(NH[sub 3])[sub 4]Ru(4-NCpy)Ru(2,2[prime]-bpy)[sub 2]Cl[sup 4+]

Journal Article · Wed Oct 02 04:00:00 EDT 1991 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00020a016· OSTI ID:7072679

Curtis, J C; Massum, M ^[1]; Roberts, J A; Blackbourn, R L; Dong, Yuhua; Johnson, C S; Hupp, J T ^[2]

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1. Univ. of San Francisco, CA (United States)
2. Northwestern Univ., Evanston, IL (United States)

Advantage is taken of oxidation-state-dependent ligand (ammine)/solvent interactions to shift redox potentials and effect redox isomerization in the title complex. In poorly basic solvents, the stable isomeric form is trans-(py)(NH[sub 3])[sub 4]Ru[sup II](NCpy)Ru[sup III](bpy)[sub 2]Cl[sup 4+] (py is pyridine; NCpy is 4-cyanopyridine; bpy is 2,2[prime]-bipyridine). In contrast, in stronger Lewis bases or in a mixture of strong and weak bases (dimethyl sulfoxide + nitromethane), the preferred isomer is trans-(py)(NH[sub 3])[sub 4]Ru[sup III](NCpy)Ru[sup II](bpy)Cl[sup 4+]. Evidence for redox isomerization was obtained, in part, from plots of formal potentials versus solvent Lewis basicity. Confirmatory evidence was obtained from a combination of electrochemical reaction entropy and resonance Raman spectroscopic experiments. UV-vis-near-IR absorption experiments, however, were not found to be useful in demonstrating isomerization. In a released series of experiments, redox isomerization was also demonstrated based on ammine binding by either a low molecular weight poly(ethylene glycol) species or by a macrocyclic ligand, dibenzo-36-crown-12. Much smaller molar amounts of either the polymer (substoichiometric) or crown (approximately stoichiometic) are required, in comparison to basic solvent (several-fold excess), in order to induce isomerization in nitromethane as the initial solvent. The possible general utility of the redox isomerization concept in time-resolved intramolecular charge-transfer studies and in optical studies of competitive hole- and electron hole- and electron-transfer pathways is mentioned.

• DOE Contract Number: FG02-87ER13808
• OSTI ID: 7072679
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 30:20; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400* -- Electrochemistry
ABSORPTION SPECTROSCOPY
ALCOHOLS
AMMINES
AZINES
BASES
BIPYRIDINES
CATIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
COMPLEXES
DATA
ENTROPY
EXPERIMENTAL DATA
GLYCOLS
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
INFRARED SPECTRA
IONS
ISOMERIZATION
LASER SPECTROSCOPY
LEWIS BASES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC POLYMERS
PHYSICAL PROPERTIES
POLYETHYLENE GLYCOLS
POLYMERS
PYRIDINES
RAMAN SPECTROSCOPY
REDOX POTENTIAL
REDOX REACTIONS
RUTHENIUM COMPLEXES
SOLVENT PROPERTIES
SPECTRA
SPECTROSCOPY
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPLEXES
ULTRAVIOLET SPECTRA
VALENCE
VISIBLE SPECTRA
VOLTAMETRY