Iridium Ir

The most sensitive analytical line for iridium is at 208.882 nm with a characteristic concentration of about Co = 3.2 mg/L in a reducing air/acetylene flame, and a linear working range up to about 55 mg/L. Iridium may also be determined in a nitrous oxide/acetylene flame with about a factor of two lower sensitivity, but significantly reduced interferences. The characteristic mass at this line, using a transversely heated graphite tube atomizer, is mo = 120 pg. No further information is available about the determination of this element. 

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Among complexes of bidentate ligands, the dithiocarbamate Ir[S2CN(CH2)4]3 has octahedrally coordinated iridium (Ir-S 2.38 A) [153],... 

A particularly interesting case is that of the platinum metal group which, in addition to platinum (Pt), comprises ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), and palladium (Pd). These carbonyl halides are usually the most practical precursors for metal deposition because of their high volatility at low temperature. Indeed two of them, palladium and platinum, do not form carbonyls but only carbonyl halides. So does gold. 

The platinum-group metals comprise ruthenium (Ru), rhodium (Rh) and palladium (Pd) from the second transition series and osmium (Os), iridium(Ir), and platinum (Pt) from thethird transition series. Little or no C VD investigation of palladium and osmium have been reported and these metalsarenotincludedhere. The properties of the other platinum-group metals are summarized in Table 6.9. 

In the case of cyclopentenyl carbamate in which a directive group is present at the homoallyl position, the cationic rhodium [Rh(diphos-4)]+ or iridium [Ir(PCy3)(py)(nbd)]+ catalyst cannot interact with the carbamate carbonyl, and thus approaches the double bond from the less-hindered side. This affords a cis-product preferentially, whereas with the chiral rhodium-duphos catalyst, directivity of the carbamate unit is observed (Table 21.7, entry 7). The presence of a hydroxyl group at the allyl position induced hydroxy-directive hydrogenation, and higher diastereoselectivity was obtained (entry 8) [44]. 

The first iridium complex used in PHOLED devices was fac tris(2-phenylpyridine) iridium Ir(ppy)3 complex [282]. It has a short triplet lifetime ( 1 ps) and high phosphorescent efficiency (p = 40% at room temperature in solution) [283]. However, in the solid state, most iridium complexes showed very low phosphorescent QE due to aggregate quenching. In most cases, the complexes have to be diluted in host materials to avoid reducing the... 

PHOLEDs also show excellent stability under display drive conditions. First generation phosphorscent dopants such as PtOEP, fac tris(2-phenylpyridine)iridium (Ir(ppy)3), and iridium(III)/Vv(2-phcnylquinolyl-jV,C2)acetylacetonate (PQ2Ir(acac)) have demonstrated lifetimes of several thousands of hours [60,96], Recent PHOLEDs have shown lifetimes in excess of 30,000 h at display brightnesses [97]. 

Another efficient material introduced by the same group is the green emitting /ac-tris(2-phenylpyridine)iridium [Ir(ppy)3, 67] [38], A suitable host for this phosphorescent emitter is CBP (10). The triplet lifetime is rather short, the experimentally determined value being 500 ns in the CBP matrix. Another iridium complex was shown to emit in the red with high efficiency due to the short phosphorescence lifetime in comparison with PtOEP [165]. 

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