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

Journal Article · Sat Jan 01 00:00:00 EST 1983 · 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), Vol. 105:8
• Country of Publication: United States
• Language: English

Related Subjects

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