Iridium complexes clusters

Iridium carbonyl clusters of several nuclearities (2, 4 and 6) have been prepared by a controlled carbonylation of [lr(CO)2(acac)] complex adsorbed in the cages of a NaY zeolite. Then, decarbonylation of the clusters gave rise to lr2, lr4 and Ir frames. Studies of the dependence of the catalytic activity on the size of the iridium frames in NaY zeolites show that there is no simple explanation for the variation in catalytic performance in ethene hydrogenation with cluster size [208]. 

Dihapto 7>ligands, in copper complexes, 2, 174 Dihydride iridium complexes, preparation, 7, 396 Dihydrido clusters, with decarutheniums, 6, 1036 Dihydrobenzofuran, carbene C-H insertions, 10, 193 Dihydrobenzopyran, carbene C-H insertions, 10, 193 ring-closing diene metathesis,... 

Fluorinated ionic liquids, characteristics, 1, 854 Fluorinated molecules, coordination, 1, 727 Fluorinated thiols, in nanoparticle preparation, 12, 80 Fluorination, and iridium carbonyl cluster complexes, 7, 299... 

Adams RD, Captain B, Smith JL Jr, Hall MB, Beddie CL, Webster CE (2004) Superloading of tin ligands into rhodium and iridium carbonyl cluster complexes. Inorg Chem 43 7576... 

The counterion as well was found to strongly influence catalyst performance. Initial experiments with Ir-PHOX complexes gave high enantioselectivity and full conversion, but only at high catalyst loadings of 4 mol% (Scheme 2b) [9]. Lower catalyst loadings resulted in decreased conversion due to catalyst deactivation [14] with concomitant formation of an inactive trinuclear iridium hydride cluster 8 (Scheme 4) [15], analogous to the deactivation products observed with the Crabtree catalyst 6 [16]. 

A labeling efEciency of 11% was estimated from spectroscopic measurements. The tetra-iridium cluster was clearly visualized in three-dimensional density maps at good resolution despite the relatively low site occupancy. Interestingly, cysteine residues inaccessible to undecagold reagent were reached with the much smaller tetra-iridium complex 45 [81]. 

The use of the cobalt triad carbonyls as catalysts continues to provide many papers for this report. Publications cover the silylformylation of 1-Hexyne catalyzed by diodium-cobalt carbonyl clusters the formation of hydroxycarbene cobalt carbonyl derivatives, the use of rhodium cluster carbonyls in the water-gas shift reaction Rh4(CO) 2> and Co3Rh(CO)] 2 catalysts for the hydrosilation of isoprene, cyclohexanone and cyclohexenone catalytic reduction of NO by CO and the carbonylation of unsaturated compounds The chemistry of iridium carbonyl cluster complexes has been extended by making use of capping reactions with HgCl2and Au(PPh3)Q... 

The dimeric complexes [M2(CO)io] (M = Mn or Re) continue to be actively studied. The presence of 17-electron free radicals, [M(CO)s], as intermediates in the thermal substitution reactions, and the chemistry of these and other 17-electron complexes are the questions being addressed. Substitution reactions of cobalt and iridium carbonyl clusters, with an attempt to define and separate electronic and steric effects, has also been an especially active area. This chemistry is discussed in Section 10.1.4. 

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