Iridium Carbonyl Complexes

By contrast, reaction of XeFi with the iridium carbonyl complex cation [Ir(CO)3(PEt3)2] in CH2CI2 results in addition across one of the Ir-CO bonds to give the first example of a metal fluoroacyl complex ... 

Polymetallic iridium carbonyl complexes, preparation, 7, 291 Polymetallic nickel—alkenes, synthesis and reactivity, 8, 139 Polymetallocenes... 

Several systematic experimental and computational studies have compared the sigma-donating abilities of NHCs and tertiary phosphines for a variety of transition-metal complexes [8-17]. As illustrative examples, analyses of the nickel-carbonyl complex 1 and iridium carbonyl complex 2 (Fig. 1) re-... 

Chloro- and other halo- containing carbonyl compounds of iridium may also be synthesized under mild conditions. Unlike [Rh(CO)2Cl]2, [Ir(CO)2Cl] is not obtainable by the direct reaction of an iridium chloride solution with CO. Instead, [Ir(CO)2Cl2]n (48) is obtained in low yields by reaction between IrCl3-H20 and carbon monoxide. The predominant mononuclear compound obtained upon carbonylation of iridium chloride salts is the tricarbonyl [Ir(CO)3Cl] (49), which appears in the sohd state to be a polymeric array consisting of stacking square-planar Ir(CO)3Cl units with short fr-Ir bonds. Even though [Ir(CO)3Cl] is polymeric, it is sublimable and is stiU a convenient source of iridium(I) containing carbon monoxide. (49) will react with a number of nucleophiles to form mononuclear iridium carbonyl complexes. 

Isocyanates can be prepared from azides by reaction with carbon monoxide. The reaction has been at first reported to proceed only with catalysis of rhodium or iridium carbonyl complexes . Later work has however shown that aryl azides and carbon monoxide interact without catalysis at temperatures of 160-180° and pressures of 200-300 atm, yielding aryl isocyanates (86) in good yields. Ethyl azidoformate yielded under these conditions ethoxyisocyanate . 

Fig. 7.1 Differences in the trans- and mer-geometries of iridium carbonyl complexes...

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 compoimds organoiridium and iridium carbonyl complexes were also previously reviewed. Iridium complex chemistry has been reviewed (1980) along with rhodium," and in annual reviews. Additionally, iridium complexes have been treated in Comprehensive Inorganic Chemistry . ... 

The harder metals at the top of the groups are more reactive towards carbonyl insertion. Thus iridium carbonyl complexes are less reactive than the rhodium and cobalt homologues. The following also apphes ... 

Spectroscopic studies on metal carbonyl complexes were relatively abundant in 1993. They include Iridium carbonyl complexes investigated via NMR O NMR studies on (mesitylene)M CO)3 complexes (M = Cr, Mo, W) an interesting NMR method for optimizing the study of slow chemical exchange has been announced natural abundance 0 NMR spectra of metal carbonyl clusters of the iron triad . 

Papers dealing with the general reactions of phosphorus group ligan s in the realm of the metal carbonyls are also represented in this report. Basolo and co-workers have examined the kinetics of CO substitution in a number of iridium carbonyl complexes and have found the first examples of a dissociative mechanism for CO substitution in the cobalt triad carbonyl complexes. Bridged diarsinidene complexes are also reported. ... 

Thus, to understand how this compound is produced, the reactivity of (PNP)Ir(H)2 complex (101) was explored with carbon monoxide. The addition of CO to a CH2CI2 solution of complex (101) resulted in the immediate and quantitative formation of the cis-dihydride carbonyl complex (102). This compound is not stable in solution at room temperature, even under an atmosphere of hydrogen, and undergoes reductive elimination of hydrogen to yield the iridium carbonyl complex (103) (Scheme 2.47). 

In the last decade, iridium carbonyl complexes have found many applications in homogeneous and heterogeneous catalysis, as well as in photoluminescent and optoelectronic devices. These aspects will be described in the corresponding sections. Here are summarized the main developments in the synthesis, characterization, and some, although brief, descriptions of use of the most remarkable iridium mono-, di-, polycarbonyl and cluster complexes. Specific reactivity of alkyl, aryl iridium carbonyl complexes are dealt with in the appropriate paragraph in this chapter. 

Evaluation of the donor properties of the corresponding iridium carbonyl complexes indicated that the nature of the substituent does not influence the donor properties of the carbene significantly. In addition, these investigations confirmed that triazolylidenes are less strong donors than analogous abnormal carbenes derived from imidazole. 

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