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Iridium complexes, photolysis

To our knowledge, the first published report of a photocatal-ytic reaction at elevated pressure was W. Strohmeyer1s hydrogenation of 1,3-cyclohexadiene under hydrogen at 10 atm /22/. On photolysis, the iridium complex 8 formed a very active catalyst, probably by dissociation of a phosphine ligand (Equation 17). At 70 C, with hydrogen at 10 atm, and a catalyst/substrate ratio of 1/100,000, the activity was 196 per minute and the turnover number was 96,000 mol of product/mol catalyst. [Pg.151]

According to theoretical calculations [114], the most stable modification of a neutral P8 ligands is expected to be the cuneane structure (C), which is found in the phosphorus allotrope known as Hittorff s phosphorus [115,116]. Surprisingly, a ligand conforming to this structural motif has been stabilized in the mixed iron/iridium complex [ Cp Ir(CO) 2(p,q2 2 1 1 1-P8) Cr(CO)5 3] (90), prepared either by photolysis or thermolysis of [Cp Ir(CO)2] with P4 in the presence of excess [Cr(CO)5(thf)] (Scheme 4) [35]. The same unit has also been recognized in the iron derivatives [[CpMeFe(CO) 2(p,q2 2 l l-P8)[CpMeFe(CO)2 2]... [Pg.133]

Difluoroketene is even more unstable but has been successfully generated in an argon matrix at 7 K by photolysis of difluoroacetylene at 193 nm, forming difluorovinylidene, which led to difluoroketene upon oxygenation by CO2. The ketene was identified by its IR band at 2162 cm f Upon further photolysis it underwent decarbonylation to CF2 (Scheme 7.39). An iridium complex of difluoroketene has also been characterized. [Pg.248]

Complexes of rhodium, iridium and ruthenium have also been used as homogeneous catalysts in the photochemical carbonylation of benzene and other reactions that involve C-H bond cleavage in hydrocarbons. It has been found that long-term continuous photolysis of benzene solutions containing CO and one of the rhodium or iridium complexes RhCl(CO)(PPh3)2, RhH(CO)(PPh3)3, or IrCl(CO)(PPh3)2 leads to the formation of benzaldehyde ... [Pg.91]

The mechanism of alkane activation by all the three iridium complexes, involves OA. For 2.66 and 2.67, electronic and coordinative unsaturations are generated by subjecting them to photolysis. On photolysis, 2.66 and 2.67 lose hydrogen and one CO, respectively, and generate 16-electron intermediates. As shown by (2.3.5.1) and (2.3.5.2), alkanes can then oxidatively add to the electronically unsaturated intermediates. [Pg.58]

Similarly to the nickelacyclopentanes, related complexes of platinum and iridium also yielded cyclobutanes on thermolysis,130 132 while palladacyclopentanes on thermolysis or photolysis generally gave cyclobutane in > 20% yield.135-136 Examples are given in Table 3. [Pg.342]

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. [Pg.188]

Flash photolysis of the rhodium(I) and iridium(I) complexes MCl(CO)(PPh3)2 in benzene leads to formation of the unsaturated species MCl(PPh3)2, the reaction kinetics of which have been investigated. Reactions with CO to reform MCl(CO)(PPh3)2 occur with second order rate constants of 7 x 10 and 2.7 x 10 M ls l for M = Rh and Ir, respectively. The RhCl(PPh3)2 species also undergoes fast reactions with PPh ... [Pg.197]

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. [Pg.103]

Two 16-electron intermediates dominate the carbon-hydrogen activation research on iridium centers. The complex Cp Ir(CO), studied by Graham and coworkers, and the complex Cp Ir(PMe3), studied by Bergman and coworkers, activate saturated carbon-hydrogen bonds. The 16-electron carbonyl complex was generated by photolysis of Cp Ir(CO)2. ... [Pg.464]


See other pages where Iridium complexes, photolysis is mentioned: [Pg.29]    [Pg.369]    [Pg.1865]    [Pg.1865]    [Pg.3774]    [Pg.1447]    [Pg.1864]    [Pg.1864]    [Pg.3773]    [Pg.727]    [Pg.278]    [Pg.396]    [Pg.219]    [Pg.202]    [Pg.190]    [Pg.192]    [Pg.198]    [Pg.121]    [Pg.238]    [Pg.1102]    [Pg.1128]    [Pg.1145]    [Pg.1164]    [Pg.1848]    [Pg.1862]    [Pg.14]    [Pg.43]    [Pg.362]    [Pg.274]    [Pg.335]    [Pg.126]    [Pg.506]    [Pg.266]    [Pg.1847]    [Pg.1861]    [Pg.1865]   
See also in sourсe #XX -- [ Pg.540 ]




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Complex photolysis

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