Iridium bimetallic complex

The iridium cyclopropene complex 171 reacts with an additional equivalent of Ir(l) to open the strained ring, affording bimetallic iridacyclobutene complex 172 (Equation 89) <1994JA10032>. Labeling experiments were used to establish that the external Ir(l) reagent mediates the oxidative activation of the intact coordinated cyclopropene, with the original Ir(l)-cyclopropene coordination retained throughout the reaction. 

Lithium or potassium indenyl has been used to generate both iridium complexes and isocyanide rhodium complexes of the form (n indenyl)Rh(CNR)2. Bimetallic complexes of Co,Rh and Ir have been made using thallium fulvanate Tl2(CioH8)- With the linked permethylcyclopentadienyl lithium reagent dirhodium complexes such as (19) can be made. ... 

A two-component bimetallic catalytic system has been developed for the allylic etherification of aliphatic alcohols, where an Ir(i) catalyst acts on allylic carbonates to generate electrophiles, while the aliphatic alcohols are independently activated by Zn(n) coordination to function as nucleophiles (Equation (48)).194 A cationic iridium complex, [Ir(COD)2]BF4,195 and an Ru(n)-bipyridine complex196 have also been reported to effectively catalyze the O-allylation of aliphatic alcohols, although allyl acetate and MeOH, respectively, are employed in excess in these examples. 

Because of the relatively poor coordinating properties displayed by the P-menthyl-substituted monodentate ligands toward some catalytically useful metals like rhodium and iridium, development of the coordination chemistry of chelating phosphetanes was required. Early studies established that the bidentate ligand P(6 ),C (6 )-43 binds well to rhodium centers. It gives the chelating complex 26 with [Rh(COD)2]PF6 and the bimetallic compound 68 when reacted with [Rh(COD)Cl]2 under an atmosphere of CO (COD = cyclooctadiene Scheme 5) <19950M4983>. 

In analogous fashion, the ruthenium- or iridium-based bimetallic and trimetallic CTV complexes such as 54-57 also make excellent anion hosts. The CTV cavity, however, is wider and more shallow and hence, the BF anion is too small to be effectively bound. This is evidenced by the crystal structures of the BF J salts of 56 and the iridium analogue 57 in which the anion within the cavity is either extremely disordered or is situated to one side of the cavity. We have found that host 54 exhibits a pronounced selectivity for TcO in nonaqueous solutions, presumably as a consequence of the wide cavity in conjunction with the larger anion size.104,109 Indeed, the X-ray crystal structure of the mixed ReO CFjSOj salt shows the... 

There are several photocatalysts mimicking hydrogenase activity that are not based on metalloporphyrin systems. Among them there are mixed-valence complexes of rhodium or iridium, [41] as well as complex systems encompassing photosensitizers (eg ruthenium complexes) attached to a catalytic bimetallic centre [43], The design of more sophisticated systems approaches that of photosynthetic processes [44],... 

Berdague fa/. reported mesomorphic bimetallic systems resulting from the complexation of dicarbonylrhodium(l) and dicarbonyliridium(i) to a dimeric salicylaldimine bridged by a 1,4-diaminocyclohexyl unit (75 M = Rh, Ir). Both complexes showed a SmA phase, although that of the iridium (Cr 142 SmA 169 I) compound had a higher mesophase stability than the rhodium congener (Cr 141 SmA 145 I). 

Electron-richer dM compounds can also be considered as H2-activating alternatives to compounds with the unfavorable dM configuration. In the case of the bis-dppm bridged Rh(I)Ir(-I) complex 14, the d d configuration has been found to result in a metal-metal bonded species in which the coordination around the rhodium center is similar to that in planar homovalent d compounds. [47] The kinetic product of dihydrogen addition to 14 is consistent with the occurrence of a single-metal oxidative addition to the Rh(I) (Scheme 12). This kinetic product is thermally unstable and reductively eliminates methane from the iridium center. The overall reaction constitutes a clear example of bimetallic cooperation, since the oxidative addition to one center provokes a reductive elimination in the other metal. 

Desulfurization of thiophene by iridium complexes has been further investigated by Jones and coworkers using the diiridium complex [Cp IrH3]2(45). Thermal reaction of this bimetallic compound with thiophene in the presence of tert-butyl-ethylene leads directly to a product (46) in which both of the C-S bonds have been broken, leaving sulfide and butadiene ligands bridging the two iridium centers (Scheme 14). When d4-thiophene is used in this reaction, a d4-butadiene ligand is... 

IrsMo) prepared from the bimetallic carbonyl complex was somewhat more active for the -butane reaction at 488 K than a pure iridium catalyst, but high ethane selectivity was retained (1.43). The IraMoa complex gave a less active catalyst, with a lower value of S2 (1.08). The addition of zirconium to platinum (Pt7sZr25/C) lowered the rate of ethane hydrogenolysis about 20-fold, and raised the activation energy. ... 

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