Iridium ligand-containing complex

Oxidative addition of XY substrates to [IrL2(/x-pz)]2 [La = (CO)2, cod] and [Ir(CD)(PPh3)(/i,-pz)]2 occurs via a two-center, two-electron route toward the iridium-iridium bond-containing species 131 (960M3785 980M2743). Complex 132, which is prepared by the ligand-substitution reaction from [Ir(CO)2 (/x-pz)]2, adds methyl iodide to give 133. 

A wide range of carbon, nitrogen, and oxygen nucleophiles react with allylic esters in the presence of iridium catalysts to form branched allylic substitution products. The bulk of the recent literature on iridium-catalyzed allylic substitution has focused on catalysts derived from [Ir(COD)Cl]2 and phosphoramidite ligands. These complexes catalyze the formation of enantiomerically enriched allylic amines, allylic ethers, and (3-branched y-8 unsaturated carbonyl compounds. The latest generation and most commonly used of these catalysts (Scheme 1) consists of a cyclometalated iridium-phosphoramidite core chelated by 1,5-cyclooctadiene. A fifth coordination site is occupied in catalyst precursors by an additional -phosphoramidite or ethylene. The phosphoramidite that is used to generate the metalacyclic core typically contains one BlNOLate and one bis-arylethylamino group on phosphorus. 

The phosphoramidite ligands that are the focus of the remainder of this chapter have prompted the investigation of ligands containing related structures. Iridium complexes of aspartic acid-derived P-chirogenic diaminophosphine oxides (DlAPHOXs) catalyze the amination [62] and alkylation [63] of aUyhc carbonates (Scheme 6). With BSA as base and catalytic amounts of NaPFs as additive, branched amination and alkylation products were obtained from cinnamyl carbonates in excellent yields and enantioselectivities. However, the yields and enantios-electivities were lower for the reactions of alkyl-substituted aUyhc carbonates. Added LiOAc increased the enantioselectivities of aUyhc alkylation products. 

Apparently real metallasilsesquioxanes of cobalt, rhodium or iridium have thus far not been reported in the literature. However, several silsesquioxane ligands containing donor-substituted side chains as well as related silsesquioxane dendri-mers have been found to form complexes with cobalt and rhodium complex frag-ments.i°3.ii4 ns... 

Iridium-containing complexes have also been studied over the period reviewed <2000ICC511, 2002OM5775>. Treatment of the methoxy-functionalized ligand 98 with IrCl3 H20 in 2-propanol/water gave the chlorohydrido complex 99 (Equation 32). 

Rhodium(III) and Iridium(III) Complexes, in contrast to the b py and phen containing complexes of ruthenium(II), which invariably show a CT (tt -> d) type emission, the rhodium(III) analogs display either a metal localized (d -> d) or ligand localized luminescence (64,179-182). The tris com-... 

Scheme 11 Iridium C,N ligand-based complexes as superior catalysts for substrates containing acid-labile groups...

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