Iridium diketonates

Hydroxylamine hydrochloride was used as an indicator for the determination of Co(acac)2. The absorbance of the resulting colored solution was measured at 590 nm . Iridium -diketonates were fluorinated oxidatively with BrFs in Freon 113, followed by decomposition in 6M HCl to IrCle and spectrophotometric determination at 488 nm. ... 

Selective hydrogenation of a diketone. 4-Hydroxycyclohexanone has not been obtained in satisfactory yield by selective hydrogenation of 1,4-cyclohexanedione under homogeneous conditions. However it can be obtained in 70% yield by hydrogenation of the dione in 2-propanol with 5% ruthenium on silica. Some other metals (platinum, iridium) are more reactive, but less selective. 

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... 

Since the determination of the structure of tris(acetylacetonato)scandium (Sc—O of 2.061-2.082 A, average Sc—O 2.070(9) A), several other diketonates have been examined, though no detailed structures have been reported. The compound mer-[Sc(CF3COCHCOCH3)3] is isostruc-tural with the aluminium, gallium, rhodium, and iridium analogues, as well as those of the 3d metals V-Co whilst the dipivaloylmethanide [Sc(Me3COCHCOMe3)3] is isostructural with the iron and indium analogues. Scandium a-diketonates such as [Sc(tropolonate)3] form adducts in... 

The selective partial hydrogenation of symmetric cyclic diketones was accomplished by interrupting the reaction after the consumption of one equivalent of hydrogen, which indicates a stronger mode of adsorption for the diketone than for the ketol product. 2 The hydrogenation of 1,4-cyclohexanedione (30) to the ketol (Eqn. 18.23) was catalyzed by nickel, copper, palladium, platinum, iridium, and ruthenium. Iridium was the most active and selective of these catalysts. Hydrogenations run over this catalyst in iso-propanol at 20°C and 6 atmospheres... 

Figure 2.45 Square-planar rhodium(I) and iridium(I) / -diketonate metallomeso-gens (M = Rh, Ir X = COO, OOC, CHi)...

Bis(dicarbonyl)dichlorodirhodium, [Rh(CO)2Cl]2, is most easily obtained by passing CO saturated with ethanol over RhCl3-3H20 at ca. 100°, when it sublimes as red needles. It has the structure shown in Fig. 26-G-2, where the coordination around each Rh atom is planar, and there are bridging chlorides with a marked dihedral angle, along the CI-CI line. There appears to be some direct interaction between electrons in rhodium orbitals perpendicular to the planes of coordination. In rhodium and iridium /3-diketonates such as Rh(CO)2(acac) and in Ir(CO)2(8-quinolinolate), there is distinct metal—metal interaction in the lattice, leading to semi-conductor behaviour.3... 

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