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

Journal Article · Tue Apr 19 23:00:00 EST 1983 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00346a029· OSTI ID:5708367

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../) ..-->.. L(p/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 absorption), 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 ultraviolet incident irradiation can be driven by visible light by using these highly absorbing, antenna fragments as internal sensitizers.

• Research Organization: Clemson Univ., SC
• DOE Contract Number: AS09-80ER10671
• OSTI ID: 5708367
• 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

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AMMONIA
AZINES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
COBALT COMPLEXES
COMPARATIVE EVALUATIONS
COMPLEXES
CYANIDES
ELECTROMAGNETIC RADIATION
ELECTRONIC STRUCTURE
ENERGY TRANSFER
HETEROCYCLIC COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
IRON COMPLEXES
KINETICS
LIGANDS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PYRAZINES
PYRIDINES
RADIATIONS
REACTION KINETICS
RHENIUM COMPLEXES
RUTHENIUM COMPLEXES
SPECTRA
TRANSITION ELEMENT COMPLEXES
VISIBLE RADIATION
VISIBLE SPECTRA