Photochemistry of mixed-metal bimetallic complexes containing pentacyanoferrate(II) or pentaammineruthenium(II) metal centers. Evidence for some intramolecular energy-transfer reactions

Journal Article · Fri Dec 31 23:00:00 EST 1982 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00346a029· OSTI ID:6695855

Moore, K J; Lee, L; Figard, J E; Gelroth, J A; Stinson, A J; Wohlers, H D; Petersen, J D

The series of complexes B/sub 5/MLM'B'/sub 5/, where B/sub 5/M = (NH/sub 3/)/sub 5/Ru/sup II/ or (CN)/sub 5/Fe/sup II/, L = 4-cyanopyridine (4-CNpy), pyrazine (pz), or 4,4'-bipyridine (4,4'-bpy), and M'B'/sub 5/ = Rh/sup III/(NH/sub 3/)/sub 5/ or Co/sup III/(CN)/sub 5/, display highly absorbing metal-to-ligand charge-transfer (MLCT) bands in the visible spectral region that can be assigned as predominantly M(d/sub ..pi../*) in character. MLCT irradiation of these complexes generally leads to cleavage of either the M-L or L-M' bonds. Cleavage of the L-M' bond, a reaction characteristic of an excited state localized on M' (not the metal center initially involved in photon adsorption), is a result of intramolecular, energy-transfer processes. This phenomenon is observed only for the 4-CNpy- and 4,4'-bpy-bridged Ru(II)/Rh(III) bimetallic complexes. The pz-bridged Ru(II)/Rh(III) bimetallic complex shows little photoreactivity at either metal center. All of the Fe(II) bimetallic complexes show Fe(II)-L bond breaking as the sole photochemical process with no evidence of any intramolecular energy transfer. The quantum yields for reactions driven by intramolecular energy transfer are small (10/sup -4/ < PHI less than or equal to 10/sup -2/), but photochemical reactions normally requiring untraviolet incident irradiation can be driven by visible light by using these highly absorbing, antenna fragments as internal sensitizers. 49 references, 2 figures, 3 tables.

• Research Organization: Clemson Univ., SC
• DOE Contract Number: AS09-80ER10671
• OSTI ID: 6695855
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 105:8; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AMMINES
AZINES
BIPYRIDINES
CHEMICAL REACTIONS
COBALT COMPLEXES
COMPARATIVE EVALUATIONS
COMPLEXES
CYANIDES
DATA
ENERGY TRANSFER
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
IRON COMPLEXES
LIGANDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PYRAZINES
PYRIDINES
RHODIUM COMPLEXES
RUTHENIUM COMPLEXES
TRANSITION ELEMENT COMPLEXES