Iridium complexes nitrogen

Alkylation of sp3 C-H bonds adjacent to a heteroatom such as nitrogen and oxygen is possible. The early works using tungsten or iridium complexes involved the reaction of dimethylamine with 1-pentene (Equation (29)) and the alkylation of a C-H bond adjacent to oxygen with / r/-butylethylene.34,34a,34b... 

Coordination Compounds. A large number of iridium complexes with nitrogen ligands have been isolated, particularly where Ir is in the +3 oxidation state. Examples of ammine complexes include [Ir(NH3)6]3+ [24669-15-6], [IrCl(NH3)]2+ [295894)9-1], and trans-[Ir(03SCF3)2(en)2]+ [90065-94 4]. Compounds of IV-heterocyclic ligands include trans- [IrCl4(py)2] [24952-67-8], [Ir(bipy)3]3+ [16788-86-6], and an unusual C-metalated bipyridine complex, [Ir(bipy)2(C3,N-bipy)]2+ [87137-18-6]. Isolation of this latter complex produced some confusion regarding the chemical and physical properties of Pi(bipy)3]3+ (167). 

Iridium complexes having oxygen ligands are not nearly as extensive as those having nitrogen. Examples include acetylacetonates [Ir(P(C(5H5)3)2 (acac)H2] [64625-61-2], aqua complexes Ir(OH2)6]3+ [61003-29-0], nitrato complexes [Ir(0N02)(NH3),J2 [42482 42-8], and peroxides IrCl(P(C6I fy)3)2(02-/-(>/ I I9)2(CO) [81624-11-5]. Unlike rhodium, very few Ir(II) carboxylate-bridged dimers have been claimed and [Ir,2(OOCCI I3)4 has not been reported. Some Ir(T) complexes exhibit reversible oxidative addition of 02 to form Ir(III) complexes. That chemistry has been reviewed (172). 

Another unusual three-component coupling reaction involving an imine as intermediate has been developed by Ishii who has shown that a C-H bond adjacent to the nitrogen atom of an imine can be activated by an iridium complex. Carbo-metallation reactions of acetylenic compounds may then be achieved, which lead to unsaturated imines 155 (Scheme 8.67) [122]. 

Nitrogen-bridged iridium complexes, preparation and characteristics, 7, 377... 

We have already alluded to the diversity of oxidation states, the dominance of oxo chemistry and the cluster carbonyls. Brief mention should be made too of the tendency of osmium (shared also by ruthenium and, to some extent, rhodium and iridium) to form polymeric species, often with oxo, nitrido or carboxylato bridges. Although it does have some activity in homogeneous catalysis (e.g. of m-hydroxylation, hydroxyamination or animation of alkenes, see p. 558, and occasionally for isomerization or hydrogenation of alkenes, see p. 571), osmium complexes are perhaps too substitution-inert for homogeneous catalysis to become a major feature of the chemistry of the element. The spectroscopic properties of some of the substituted heterocyclic nitrogen-donor complexes may yet make osmium an important element for photodissociation energy research. 

The reaction of an iridium complex with furanoyl azide seems to involve coordination of the terminal nitrogen with the iridium, followed by dissociation to a stable iridium-nitrogen complex and furanoyl isocyanate (which incorporates a carbonyl that had been part of the iridium complex). 

NO, Nitrogen oxide, iridium complex, 21 104 NO2SC3H7, L-Cysteine, gold complex, 21 31 NO3C3H7, Serine, copper complex, 21 115 NFPtSe2C24H28, Platinum(II), (A. /V-diethyldi-selenocarbamato)methyl(triphenylphos-phine)-, 21 10... 

Figure 6. One electron oxidation of [M (R)(CO)(PP1i3)3] or release of nitrogen monoxide ftom [Ir (Cl)(NO )(CO)(PPh3)]" yields paramagnetic rhodium or iridium complexes of the type [M (R)(CO)(PPh3)3]+.

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