Iridium, tris

The bis platinum(II) complex Pt(Thpy)2, which has an excited state lifetime in acetonitrile solution of 2.2 ps at 293 K, resembles the similar tris iridium(in) complex Ir(Phpy)3, which has a lifetime of 2.0 ps at 293 K. This iridium(III) complex, by contrast with the platinum(II) complex, cannot undergo oxidative addition reactions, but it can undergo photoredox reactions. Thus the reduction potential for the Ir(Phpy)3/Ir(Phpy)3 couple is -1.8 V versus SCE, which makes... 

Subsequentiy, the PGM solution is oxidized and acidified to reconvert Ir(III) to Ir(IV). Tri- -octylamine is again used as the extractant, this time to extract iridium. The iridium ia the organic phase is reduced to Ir(III) and recovered. The remaining element is rhodium, which is recovered from impurities in the original solution by conventional precipitation or ion exchange (qv). 

Reaction of the cyclopentadienyl rhodium and iridium tris(acetone) complexes with indole leads to the species 118 (M = Rh, Ir) [77JCS(D)1654 79JCS(D)1531]. None of these compounds deprotonates easily in acetone, but the iridium complex loses a proton in reaction with bases (Na2C03 in water, r-BuOK in acetone) to form the ri -indolyl complex 119. This reaction is easily reversed in the presence of small amounts of trifluoroacetic acid. 

Rhodium-on-carbon has also been found to bring about the formation of 2,2 -biquinoline from quinoline, the yield and the percentage conversion being similar to that obtained with palladium-on-carbon. On the other hand, rhodium-on-carbon failed to produce 2,2 -bipyridine from pyridine, and it has not yet been tried with other bases. Experiments with carbon-supported catalysts prepared from ruthenium, osmium, iridium, and platinum have shown that none of these metals is capable of bringing about the formation of 2,2 -biquinoline from quinoline under the conditions used with palladium and rhodium. ... 

In the rhodium and iridium complexes, the C-coordination, carbene function, and cyclometallated cases prevail. Benzothiazole-2-thione was studied extensively as a ligand and various situations of the exocyclic S-monodentate coordination as well as N,S-combinations in the di-, tri-, and tetranuclear species were discovered. 

Bis-[triphenylphosphin]-carbonyl-organo-rhodium(0) bzw. -iridium(O) sind aus den entsprechenden Dichloro-Komplexen bzw. Carbonyl-tris-[triphenyl-phosphin]-rhodium(0) bzw.-iridium(O) aus den Chloro-Komplexen zuganglich7 ... 

Antimony, arsenic, selenium, tellurium, iridium, iron, molybdenum, osmium, potassium, rhodium, tungsten (and when primed with charcoal,) aluminium, copper, lead, magnesium, silver, tin, zinc. Interaction of lithium or calcium with chlorine tri- or penta-fluorides is hypergolic and particularly energetic. 

Szabo-Nagy and Keszethelyi (1999 and 2000) have carried out experiments which show a possible violation of parity in the crystallisation of racemates of tris(l,2-ethylenediamine-Co(III)) and the corresponding iridium compound. 

These spectra show even fewer features than those of the palladium catalysts. Absorption takes place almost exclusively in the region 2000-2100 cm-1. There are some weak bands below 2000 cm-1, but our experimental method did not allow us to determine their frequencies with reasonable accuracy. It is clear that also with the iridium catalysts the particle size has an effect on the spectra. The spectrum of Ir-8 shows only one intense band at 2048 cm-1, whereas the other two have additional bands at higher frequencies. There is also a marked dependence of the intensity of the 2048 cm-1 band on the CO pressure, especially in the case of Ir-37 and Ir-100. We shall not try to interpret the CO spectra of the iridium samples, as we consider the data available insufficient for the purpose. 

Orpen, A.G., Pringle, P.G., Smith, M.B., and Worboys, K., Synthesis and properties of new tris(cyanoethyl)phosphine complexes of platmum(0,II), palladium, II), iridium(I) and rhodium(I). Conformational analysis of tris(cyanoethyl)phosphine ligands, /. Organomet. Chem., 550, 255, 1998. 

C Adachi, MA Baldo, SR Forrest, and ME Thompson, High-efficiency organic electrophosphor-escent devices with tris(2-phenylpyridine)iridium doped into electron-transporting materials, Appl. Phys. Lett., 77 904-906, 2000. 

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... 

Once again, the most recent developments have been in the area of green phosphorescent materials where phenomenal efficiencies are now beginning to be coupled with good device lifetimes. The prototypical emitter of this type is iridium-tris-2-phenylpyridine (Ir(ppy)3) used as a dopant (Scheme 3.98), usually diluted into a carbazole type host, because it is prone to serious self-quenching problems. 

K. Dedeian, P.I. Djurovich, F.O. Garces, G. Carlson, and R.J. Watts, A new synthetic route to the preparation of a series of strong photoreducing agents fac tris-ortho-metalated complexes of Iridium (III) with substituted 2-phenylpyridines, Inorg. Chem., 30 1685-1687 (1991). 

K. Dedeian, J. Shi, N. Shepherd, E. Forsythe, and D.C. Morton, Photophysical and electrochemical properties of heteroleptic tris-cyclometalated Iridium(III) complexes, Inorgan. Chem., 44 4445-4447 (2005). 

C Lee, KB Lee, and J Kim, Polymer phosphorescent light-emitting devices doped with tris (2-phenylpyridine) iridium as a triplet emitter, Appl. Phys. Lett., 77 2280-2282, 2000. 

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]. 

Ir4(CO)ii(PPh3)149 The structures of the di- and tri-substituted iridium derivative are shown in Fig. 14. In all cases, the phosphines are around the basal plane. However, whereas the two phosphines are in relative trans-positions in the di-substituted compound, in the tris-derivative two of the phosphines are obliged to occupy relative c/s-position and, as a result, are involved in more steric interaction. 

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]. 

R. J. Watts, J. S. Harrington, and J. Van Houten, A stable monodentate 2,2-bipyridine complex of iridium (III) A model for reactive intermediates in ligand displacement reactions of tris 2,2-bipyridine metal complexes, J. Am. Chem. Soc. 99, 2179-2187 (1977). 

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