21311-02-4Relevant academic research and scientific papers
Emission and photochemistry of M(CO)4(diimine) (M = Cr, Mo, W) complexes in room-temperature solution
Manuta, David M.,Lees, Alistair J.
, p. 1354 - 1359 (2008/10/08)
Electronic absorption, emission, and photochemical data are reported for a series of M(CO)4L complexes, where M = Cr, Mo, or W and L = 2,2′-bipyridine, 1,10-phenanthroline, or a derivative diimine ligand. Low-energy ligand field (LF) and intense metal-to-ligand charge-transfer (MLCT) transitions are observed in the electronic absorption spectra. The energy positions of the MLCT transitions are extremely sensitive to the nature of ligand substituent and solvent medium. Each complex exhibits dual emission features at 298 K in the 500-850-nm region and two low-lying M → π*(L) transitions are implicated in the radiative decay process. Quantum efficiencies for photosubstitution (φ) have been determined following excitation into the low-lying excited states. The photoreaction efficiences depend substantially on the irradiation wavelength; e.g., for W(CO)4(bpy) in benzene LF excitation at λ = 395 nm yields φ = 1.2 × 10-2, whereas MLCT excitation at λ = 514 nm yields φ = 5.4 × 10-5. Photosubstitution data indicate that a LF state is largely responsible for the photochemistry in these M(CO)4L complexes. The photoefficiencies following MLCT excitation at 514 nm are only slightly temperature-dependent, indicating that either the MLCT state is intrinsically photoactive or another excited state lies close in energy and contributes to the photochemistry. The suggestion of photoreaction from the low-lying LF triplet state (1A → 3E) is discussed. An excited-state scheme relating the photochemical and emission data is presented.
ELECTRODE-CATALYZED SUBSTITUTION OF M(CO)4bipy (M=Cr, Mo, W) INITIATED BY REDUCTION
Miholova, D.,Vlcek, A. A.
, p. 317 - 326 (2007/10/02)
One CO group is labilized and substituted by triphenylphosphine in radical anions formed by the electrochemical reduction of M(CO)4bipy=2,2-bipyridyl; M=Cr, Mo, W).The reaction proceeds as an electrode-catalyzed process.It is shown that the release of the
