Iridium complexes 3-diketonates

IR, Raman and 13C NMR spectroscopic studies have been performed on various [Ir(acac)(L)2] complexes (L = ethylene, propene, vinyl chloride, vinyl acetate, methyl acrylate, styrene) for the elucidation of the bonding between Ir and the alkene ligand.142 Also, the square planar iridium(I) acetylacetonate complexes [Ir(LL)(L )2], where LL is a /J-diketonate and L is CO or ethylene, have been studied by UVPES.143 The enthalpies of reaction of the crystalline [Ir(acac)(L)2] complexes with gaseous CO (reaction 28) have been determined by differential scanning calorimetry. The enthalpies for the gaseous reaction have been derived from these results and Ir—L bond strengths estimated.143... 

Iridium(III) complexes incorporating /3-diketonate ligands include Ir(acac)3 (equation 19), y-halogenated derivatives," ... 

Iridium(in) /8-diketonates show a relatively week absorption in the 350-400 nm range, that can be ascribed to spin-aUowed MLCT transitions. Electroluminescent spectra (EL) show green light emission. In electronic spectra of Ir(III)), Pt(II), Ru(II) and Os(II) /3-diketonates " weak absorption bands between 330 and 560 nm can be assigned to singlet and triplet MLCT transitions. The n n transition from the complexes are blue-shifted for about 20 mn compared with the free ligands. 

Two recent determinations of activation volumes for Mel addition to rhodium(I) 8-diketonate complexes (197) could not discern which type operated. The values, along with those of AS - and the effects of solvent change, clearly indicated development of polar transition states (the charge separation involved in either 29 or 30 would fit) and the authors marginally favored 29. Interestingly, a complex of iridium(III) and Mel, 31, has been structurally characterized and reveals iodide-bonded Mel molecules (198). The Ir-I-C bond angles are 105.5° and 108.2° and although the interaction can be considered nucleophilic... 

Ruthenium(III), d, is ruthenium s most stable oxidation state and resembles rhodium(III) and iridium(III) more than osmium(III). The salts inelude the halides, hydroxides, and oxides RuCls SHaO is most important because it is a good starting material for other compounds and reacts readily with olefins and phosphines. Complexes of this oxidation state are known with water, eyanide, oxygenated organies, sueh as diketones and earboxylates, pyridines, earbonyls, ey-elopentadienyls, phosphine, and arsine ligands. A notable differenee between ruthenium(II) and ruthenium(III) is the absenee of ruthenium(III) nitrosyl complexes. 

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