Iridium complexes photochemistry

Ruthenium complexes used to lead research in photochemistry of metal compounds, but rhodium complexes have recently overtaken them as the key target compounds due to their applications in OLEDs. This is a lively and ever-changing field for example, over 90% of luminescent iridum(III) complexes have been reported only in the six years to the beginning of 2009. With their luminescence tuneable through ligand choice, iridium complexes are firm candidates for optical display applications. 

The extensive activity in coupling reactions by catalysis by transition metal complexes and the expertise in photochemistry have been joined for opening new paths for organic synthesis. An iridium complex, /ac-tris[2-phenylpyridinato-C2,N] iridium(ni) acts as energy transfer sensitizer in the uphill isomerization to the Z isomer of a variety of p-alkylslyrenes 4, with blue LEDs as light source (Scheme 5). ... 

The photochemical studies of transition metal hydride complexes that have appeared in the chemical literature are reviewed, with primary emphasis on studies of iridium and ruthenium that were conducted by our research group. The photochemistry of the molybdenum hydride complexes Mo(tj5-C5H5)2M2] and [MoH4(dppe)2] (dppe = Ph2PCH2CH2PPh2), which eliminate H2 upon photolysis, is discussed in detail. The photoinduced elimination of molecular hydrogen from di-and polyhydride complexes of the transition elements is proposed to be a general reaction pathway. 

Mo(r75-C5H5)2H2] and [MoH dppe ]. Our studies of the di- and trihydride complexes of ruthenium and iridium, described above and published previously (27,35), and those of other workers (discussed at the beginning of this chapter), indicate that photoinduced elimination of molecular hydrogen is a common reaction pathway for di- and polyhydride complexes. To demonstrate the photoreaction s generality and its utility for generating otherwise unattainable, extremely reactive metal complexes, we have begun to study the photochemistry of polyhydride complexes of the early transition metals. We focused initially... 

Arylation, olefins, 187, 190 Arylketimines, iridium hydrogenation, 83 Arylpropanoic acid, Grignard coupling, 190 Aspartame, 8, 27 Asymmetric catalysis characteristics, 11 chiral metal complexes, 122 covalently bound intermediates, 323 electrochemistry, 342 hydrogen-bonded associates, 328 industrial applications, 8, 357 optically active compounds, 2 phase-transfer reactions, 333 photochemistry, 341 polymerization, 174, 332 purely organic compounds, 323 see also specific complexes Asymmetric induction, 71, 155 Attractive interaction, 196, 216 Autoinduction, 330 Axial chirality, 18 Aza-Diels-Alder reaction, 220 Azetidinone, 44, 80 Aziridination, olefins, 207... 

Reviews have appeared of the photophysics of molybdenum complexes, primary and secondary processes in organometallic chemistry, flash photolysis of Pe(CO)5 and Cr(CO)g, dinuclear manganese carbonyl compounds, the photochemistry of metal complexes isolated in low temperature matrices, cluster complexes, diene complexes, photoproduction of coordinativeiy unsaturated species containing rhodium or iridium, and redox chemiluminescence of organometallic compounds.Synthetic and metal organic photochemistry in industry has also been reviewed. 

One notable area of chemistry that can offer some prospects for enhanced displacement of ligands is photochemistry. The photochemistry of metal complexes has been extensively studied and reviewed (16, 282), and it is not proposed to cover this area in any detail. One of the complications in photochemistry of metal complexes is the marked change in reactivity even within a triad of the d block. For example, the reaction modes of the simple [M(NH3)5N3]2+ ions for the cobalt triad vary clearly. For cobalt(III), the photochemistry is dominated by an intramolecular redox reaction (93) whereas for iridium(III), reac-... 

Photolysis of Fe(CO)5 in the presence of olefins leads to formation of olefin complexes which exhibit catalytic properties. The complex [Fe(cyclooctene)2 ( 0)3] catalyzes isomerization of olefins in alkene solutions. The compound Fe(C2H4)(CO)4 which is formed in the gas phase by photolysis of Fe(CO)5 and ethylene catalyzes hydrogenation of 2114. Photochemistry of the following dinuclear complex of iridium(I) is interesting ... 

Two papers give information relating to solvent effects in photochemistry of iridium(III) diimine complexes " mechanisms of photosubstitution at iridium(III) feature in two review articles. 

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