Iridium complexes nitrosyls

Examples of the osmium and iridium complexes are Os(PPh3)2Cl(NO) and Ir(PPh3)3(NO), respectively [216]. The osmium compound gave, on reaction with HC1, the first characterized complex with the feature of an N-coordinated HNO, Os(PPh3)2Cl2(HNO), which was confirmed by X-ray crystallography. On the other hand, the nitrosylated iridium compound gave the hydroxylamine complex [216]. 

Several iridium( —I) nitrosyl complexes are known. Those with the general formula [Ir(NO)2X(PPh3)2] (X = Cl, Br, I) are produced upon reduction of [Ir(NO)2(PPh3)2] with the appropriate lithium halide. IR spectral data for these complexes indicate bridging NO groups, as shown by the low N—O frequencies [v(N—O) 1540-1490 cm-1].7 Reaction of [Ir(NO)2X(PPh3)2] with NO results in the oxidation of NO according to reaction (l).8... 

M = Rh, 1626 cm M = Ir, 1545 cm ) led to the incorrect conclusion that different solid-state structures are adopted by the two compounds (60). However, X-ray powder data showed the rhodium material to be isomorphous with the structurally characterized iridium complex, which in the solid state has a square-pyramidal geometry and a bent apical nitrosyl ligand (61). 

Figure 2.100 Synthesis of some iridium nitrosyl complexes.

Table 2.14 Structural data for iridium nitrosyl complexes...

Figure 2.102 Addition reactions for iridium nitrosyl complexes (i (N-O) (cm ) is shown for...

Later related reactions of iridium nitrosyl complexes of a slightly different type were reported (equations 40-42). 

With respect to the derivatives of metal carbonyls, the substituted metal carbonyls of the VIB Group (e.g., Mo(CO)apya), the halogenocar-bonyls of iron, ruthenium, iridium, and platinum, the hydridocarbonyls H2Fe(CO)4 and HCo(CO)4 discovered in 1931 and 1934, and the nitrosyl carbonyls FelCOj NOjg and Co(CO)3NO were the most important (/). The known anionic CO complexes were limited to [HFe(CO)J and [Co(CO)J-. For studies of substitution reactions of metal carbonyls at this time, work was almost totally limited to reactions involving the classical N ligands such as NH3, en, py, bipy, and phen. 

The iridium(II) complex [Ir(Br)3(NO)(PPh3)2] has been reported by Malatesta and coworkers.7 A + II oxidation state assignment depends on the formalism used regarding the nitrosyl ligand. The complex is considered iridium(II) if the NO ligand is assigned as (NO)+. 

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