149253-45-2Relevant academic research and scientific papers
Preparation of five- and six-coordinate aryl(hydrido) iridium(III) complexes from benzene and functionalized arenes by C-H activation
Werner, Helmut,Hoehn, Arthur,Dziallas, Michael,Dirnberger, Thomas
, p. 2597 - 2606 (2007/10/03)
The reaction of the in situ generated cyclooctene iridium(i) derivative trans-[IrCl(C8H14)(PiPr3)2] with benzene at 80 °C gave a mixture of the five-coordinate dihydrido and hydrido(phenyl) iridium(iii) complexes [IrH2(Cl)(PiPr 3)2] 2 and [IrH(C6H5)(Cl)(PiPr 3)2] 3 in the ratio of about 1: 2. The chloro- and fluoro-substituted arenes C6H5X (X = Cl, F), C 6H4F2 and C6H4F(CH 3) reacted also by C-H activation to afford the corresponding aryl(hydrido) iridium(iii) derivatives [IrH(C6H4X)(Cl) (PiPr3)2] 7, 8, [IrH(C6H3F 2)(Cl)(PiPr3)2] 9-11 and [IrH{C 6H3F(CH3)}(Cl)(PiPr3)2] 12, 13, respectively. The formation of isomeric mixtures had been detected by 1H, 13C, 19F and 31P NMR spectroscopy. Treatment of 3 and 7-13 with CO gave the octahedral carbonyl iridium(iii) complexes [IrH(C6H3XX′)(Cl)(CO) (PiPr3)2] 5, 14-20 without the elimination of the arene. The reactions of trans-[IrCl(C8H14)(PiPr3) 2] with aryl ketones C6H5C(O)R (R = Me, Ph), aryl ketoximes C6H5C(NOH)R (R = Me, Ph) and benzaloxime C6H5C(NOH)H resulted in the formation of six-coordinate aryl(hydrido) iridium(iii) compounds 21-25 with the aryl ligand coordinated in a bidentate κ2-C,O or κ2-C,N fashion. With C6H5C(O)NH2 as the substrate, the two isomers [IrH{κ2-N,O-NHC(O)C6H5}(Cl)(PiPr 3)2] 26 and [IrH{κ2-C,O-C 6H4C(O)NH2}(Cl)(PiPr3)2] 27 were prepared stepwise. Treatment of trans-[IrCl(C8H 14)(PiPr3)2] with benzoic acid gave the benzoato(hydrido) complex [IrH{κ2-O,O-O2CC 6H5}(Cl)(PiPr3)2] 29 which did not rearrange to the κ2-C,O isomer. The Royal Society of Chemistry 2006.
A mechanistic study of thermal C-H reductive elimination from a six-coordinate d6 indium complex
Rosini, Glen P.,Wang, Kun,Patel, Bhushan,Goldman, Alan S.
, p. 537 - 542 (2008/10/08)
The thermolysis of trans-IrL2(CO)Cl(H)(C6H5) (1a; L=P(i-Pr)3; H trans to CO) produces benzene and the Vaska-type complex IrL2(CO)Cl. A mechanistic study of the reaction has shown that 1a reversibly loses CO at 120 °C (as evidenced by the incorporation of 13CO) and isomerizes to the previously unreported 1b (H trans to Cl). It was found that 1b is the complex primarily responsible for the formation of benzene upon thermolysis under CO atmosphere; direct loss of benzene from 1a was determined to be, at most, a minor pathway. Benzaldehyde was also formed as a product of thermolysis of 1a under CO atmosphere. The first-order rate constant for benzene elimination in the absence of CO was found to be 8.5×10-5 s-1. The presence of only 5 Torr CO results in a decrease to 2.0×10-5 s-1, but little further inhibition is observed above 5 Torr CO. Added dihydrogen (100 Torr) was found to effect a novel catalysis of benzene elimination from 1a in the absence of CO atmosphere; it is suggested that trace amounts of dihydrogen, present in solutions of 1a, are responsible for the enhanced rate of elimination in the absence of CO. The thermolysis of 1-d6 in toluene was found to proceed without any toluene incorporation, implying that arene loss is irreversible.
