Iridium, bis

CH2PBU2 ] (x = 2 and y = 1 or x = 0 and y = 2). However, with Bu NC one major intermediate product, so far only detected in solution by P-31- H-1 NMR spectroscopy, appears to be a bis-iridium complex with four bridging hydrogens. The P-31- H-1 (organic hydrogens only) pattern is very complex but symmetrical about a midpoint (38). Thus the iridium chemistry with these medium-chain diphosphines is unusual but some aspects of it still need clarification. 

Perhaps as a consequence of Johnson s failure, 20 years elapsed before Sessler and coworkers reported that certain p -type complexes could in fact be formed with heterosapphyrins.These latter workers were clearly inspired by their earlier successful syntheses of p -type rhodium(I) and iridium(I) carbonyl complexes of pentaazasapphyrins 5.21 and 5.23 vide supra). Thus, in a first experiment, they treated the monothiasapphyrin 5.71 with Rli2(CO)4Cl2 (Scheme 5.5.4). This afforded the structurally characterized [Rh(CO)2]2 monothiasapphyrin complex 5.100 (Figure 5.5.6). Subsequently, they prepared the bis-iridium complex 5.101 of the mono-selenasapphyrin 5.73. This complex was also characterized by X-ray diffraction analysis. The resulting structure then served to confirm the expected sitting-a-top binding mode (Figure 5.5.7). 

Ruiz-BoteUa S, Guisado-Barrios Mata JA, Peris E. Coordination singularities of a bis(p-xylyl)bis(benzimidazolylidene) ligand and the bis-iridium and rhodium-related complexes. OrganometalUcs. 2013 32 6613-6619. 

Iridium, dicarbonylcyclopentadienyl-reaction with hexafluorobut-2-yne, 1, 666 Iridomyrmecin crystallography, 3, 624 Iron, bis(borinato)-, 1, 645 Iron, bis(l-methylborinato)-deborination, 1, 645... 

Cases of the S-coordinated rhodium and iridium are quite scarce. To complete the picture, we next consider the possibilities of S-coordination using complicated derivatives of thiophene. 2,5-[Bis(2-diphenylphosphino)ethyl]thiophene is known to contain three potential donor sites, two phosphorus atoms and the sulfur heteroatom, the latter being a rather nucleophilic center (93IC5652). A more typical situation is coordination via the phosphorus sites. It is also observed in the product of the reaction of 2,5-bis[3-(diphenylphosphino)propyl]thiophene (L) with the species obtained after treatment of [(cod)Rh(acac)] with perchloric acid (95IC365). Carbonylation of [Rh(cod)L][C104]) thus prepared yields 237. Decarbonylation of 237 gives a mixture of 238 and the S-coordinated species 239. Complete decarbonylation gives 240, where the heterocycle is -coordinated. The cycle of carbonylation decarbonylation is reversible. 

An unusual variation in kinetics and mechanisms of decomposition with temperature of the compound dioxygencarbonyl chloro-bis(triphenyl-phosphine) iridium(I) has been reported by Ball [1287]. In the lowest temperature range, 379—397 K, a nucleation and growth process was described by the Avrami—Erofe ev equation [eqn. (6), n = 2]. Between 405 and 425 K, data fitted the contracting area expression [eqn. (7), n = 2], indicative of phase boundary control. At higher temperatures, 426— 443 K, diffusion control was indicated by obedience to eqn. (13). The... 

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 ... 

More recently, the same type of hgand was used to form chiral iridium complexes, which were used as catalysts in the hydrogenation of ketones. The inclusion of hydrophihc substituents in the aromatic rings of the diphenylethylenediamine (Fig. 23) allowed the use of the corresponding complexes in water or water/alcohol solutions [72]. This method was optimized in order to recover and reuse the aqueous solution of the catalyst after product extraction with pentane. The combination of chiral 1,2-bis(p-methoxyphenyl)-N,M -dimethylethylenediamine and triethyleneglycol monomethyl ether in methanol/water was shown to be the best method, with up to six runs with total acetophenone conversion and 65-68% ee. Only in the seventh run did the yield and the enantioselectivity decrease slightly. 

It is found that the tetra-isoamylphosphonium cation does not take a roughly spherical shape but accommodates an iodide ion 480 pm from the phosphorus atom. Neutron diffraction of phosphonium bromide crystals shows no evidence of hydrogen-bonding. The ructures of bis(trimethylphosphine)silicon tetrachloride and the iridium salt (134) are also reported. 

The reversible complexing of carbon dioxide by bis[bis(l,2-diphe-nylphosphino)ethane]iridium(I) chloride, [Ir(dpe)2]Cl, in acetonitrile [Eq. (36)] (48) appears not to involve carboxylation of a cyanomethylir-idium(III) complex or its formation by decarboxylation of the cyanoacetate... 

Iridium(III) hydride forms complexes with DIOP, BDPP (2,4-bis(diphenyl-phosphino)pentane), NORPHOS, and BINAP ligands to produce amines in 11 -80% ee.679 Similar modest results are obtained in the reduction of N-arylketimines with an iridium(HI) complex with (2S,3 S) -C HIRA PHOS as the chiral ligand.680 The indium complexes with chiral phosphinodihydrooxazoles catalyze the enantioselective hydrogenation of imines in supercritical carbon dioxide with up to 80% ee, but generally lower ee values are observed in... 

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