Iridium complexes chemical properties

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(III) complexes have been widely explored in the past few decades because of their outstanding photophysical properties and superior photo- and chemical stability (123-129). Much effort has been devoted to both neutral and cationic luminescent iridium complexes in which fine-timing of the energy of their long-lived excited state can be achieved by proper choice of the coordinated ligands (130-136). 

Rhodium and iridium have closely related chemical properties, and their metal complexes adopt similar coordination geometries. Therefore, occasionally iridium congeners were used as models to study the catalytic properties of rhodium complexes, which are less stable under catalytic conditions [4, 5]. Unfortunately, in comparison to rhodium, only a few studies with quite different catalytic systems exist, and therefore general conclusions are hard to draw. 

The electronic ground-state configuration of the free neutral atom of element 109 has been predicted to be 5f 6d 7s and thus it should belong to the group VIII elements of the periodic table [75]. Element 109 is expected to have a chemical behavior similar to iridium but may exhibit an even more noble character [75]. The oxidation states 6+ [77], 3 -H [99], and 1 -t- [78] have been predicted to be stable, and a wide variety of valence states are anticipated in aqueous solution for element 109 [75], Like Ir, element 109 should form numerous solution complexes [75], Some of the predicted chemical properties of element 109 are given in Table 13.10. 

Johnson J.A., Lisoni J.G., Wonters D.J. Iridium based electrodes for ferroelectric capacitor fabrication. Mater. Res. Soc. Symp. Proc. 2002 688 59-64 Kang J., Yoko T., Kozuka H., Sakka S. Preparation of Pb-based complex perovskite coating films by sol-gel method. In Sol-Gel Optics, vol. II, J.D. Mackenzie, ed. Pfoc. SPIE 1992 1758 249-259 Kim Dong-Joo, Maria Jon-Paul, Kingon A.I. Compositional effect on the piezoelectric and ferroelectric properties of chemical deposited PZT thin films. Mater. Res. Soc. Symp. Proc. 2002 688 351-356... 

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