Coordination chemistry iridium

The coordination chemistry of iridium has continued to flourish since 1985/86. All common donor atoms can be found bound to at least one oxidation state of iridium. The most common oxidation states exhibited by iridium complexes are I and III, although examples of all oxidation states from —I to VI have been synthesized and characterized. Low-oxidation-state iridium species usually contain CO ligands or P donor atoms, whereas high-oxidation-number-containing coordination compounds are predominantly hexahalide ones. 

This volume is concerned with fundamental developments in the coordination chemistry of the elements of Groups 9-12 since 1982. The individual chapters cover the coordination chemistry of cobalt, iridium, nickel, palladium, platinum, copper, silver and gold, zinc and cadmium, and mercury. Unfortunately, because of factors beyond the Editors control, the manuscript for the proposed chapter on rhodium was not available in time for publication. 

Surface Organometallic and Coordination Chemistry of Iridium, Platinum, and Gold Electrocatalysts... 

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>. 

The coordination chemistry of iridium is concerned primarily with the I, III and IV oxidation states complexes with iridium in the — 1,0, V and VI oxidation states are also known. Of these latter states, Ir-1 and Ir° are found in carbonylate anions, oligonuclear and substituted carbonyls, hydrides and ammines. Iridium(V) and (VI) complexes are predominantly hexahalide compounds. 

This chapter will not deal with iridium complexes in which the coordination chemistry of the iridium-carbon bond is implicated inasmuch as Leigh and Richards have very recently (1982) provided an excellent detailed review on such compounds organoiridium2 and iridium carbonyl3 complexes were also previously reviewed. Iridium complex chemistry has been reviewed (1980) along with rhodium,4 and in annual reviews.3 Additionally, iridium complexes have been treated in Comprehensive Inorganic Chemistry .6... 

The coordination chemistry of iridium(I) involves 7t-acid ligands. Both four- and five-coordinate species form. Iridium(I) complexes are invariably prepared via some form of reduction, either from analogous iridium(III) complexes or from halide complexes in the presence of the complexing ligand, or via substitution. 

Iridium metal has a cubic close-packed structure at 298 K and is stable in air and water. It is inert toward acids but reacts with fused alkalis. In many respects, the chemistry of its compounds resembles that of its group 9 congener Rh see Rhodium Inorganic Coordination Chemistry). 

Hydride Complexes of the Transition Metals Iridium Organometallic Chemistry Luminescence Macrocyclic Ligands Rhodium Inorganic Coordination Chemistry. 

The corresponding iridium enamide complexes and their alkyl hydride counterparts are much more stable, and a full NMR characterization of the alkyl hydride proved possible in the DIPAMP series. Here, as in the corresponding rhodium chemistry, the presumed dihydride precursor proved to be elusive [31]. By employing a different approach to enamide complexes in which an iridium bis-enamide complex was allowed to react with the diphosphine (Fig. 6) both major and minor enamide complexes could be prepared separately the path to one of them is shown in Fig. 6. The trick was to employ menthyl esters so that stereo-chemically homogeneous Ir complexes were formed. Some additional structural features of the intermediates were derived from detailed NMR analysis, and especially the role of the OMe group in coordinating to iridium trans to the hydride [32]. 

Tris(acetylacetonato-<9,<9) iridium(III) is a coordinatively saturated, stable species that has been examined spectroscopically1,2 and used in metal vapor deposition studies.3 4 Removal of one acac ligand (acac = acetylacetonato or 2,4-pentanedionate) generates a family of bis-(acac-<9,<9) iridium(III) complexes exhibiting rich coordination chemistry. In 1976, Bennett and Mitchell isolated these (acac-<9,<9)2Ir(III)(R)(L) complexes as intermediates in yielding preparations of the (acac-<9,<9)3Ir(III) complex from the reaction of acetylace-tone with IrCl3.5... 

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