935-31-9Relevant articles and documents
Moore
, p. 3788 (1962)
A highly stable adamantyl-substituted pincer-ligated iridium catalyst for alkane dehydrogenation
Punji, Benudhar,Emge, Thomas J.,Goldman, Alan S.
, p. 2702 - 2709 (2010)
The adamantyl-substituted pincer-ligand precursor AdPCP-H [(AdPCP = κ3-C6H3-2,6-(CH 2PAd2)2); Ad = 1-adamantyl] has been synthesized by the reaction of 1,3-dibromoxylene with di-1-adamantylphosphine in the presence of triethylamine. Treatment of AdPCP-H with [Ir(COD)Cl]2 (COD = 1,5-cyclooctadiene) affords the pincer-ligated complex (AdPCP)IrHCl, which was crystallographically characterized. Dehydrohalogenation of (AdPCP)IrHCl either with LiBEt3H or with KOtBu, under hydrogen atmosphere, yields the hydrides ( AdPCP)IrH2 and (AdPCP)IrH4. ( AdPCP)IrH2 catalyzes dehydrogenation of alkanes with a level of activity comparable to that of the previously reported ( tBuPCP)IrH2, while it is thermally much more robust than the tBuPCP analogue, as well as iPrPCP or tBuPOCOP pincer complexes.
Investigation of iridium CF3PCP pincer catalytic dehydrogenation and decarbonylation chemistry
Adams, Jeramie J.,Arulsamy, Navamoney,Roddick, Dean M.
experimental part, p. 1439 - 1447 (2012/04/10)
The iridium fluorinated pincer complex (CF3PCP)Ir(cod) (CF 3PCP = 2,6-C6H3(CH2P(CF 3)2)2) catalyzes hydrogen transfer from cyclooctane (coa) to tert-butylethylene (tbe) in 1/1 coa/tbe at 200 °C to give cyclooctene (coe) and neohexane (tba) at an initial rate of 40 TO h -1. In 5/1 coa/tbe, higher initial activity (155 TO h-1) and higher turnovers (2580 TON's after 1450 min) are found. Samples of 95% tbe contain significant amounts of isoprene (2-methyl-1,3-butadiene), which reacts with (CF3PCP)Ir(cod) to initially form (CF3PCP) Ir(isoprene). Alkene inhibition studies show that (CF3PCP)Ir is only modestly inhibited (67% reduced initial activity) in the presence of 800 equiv of added coe. Unlike donor pincer systems, no decrease in activity is noted under 1 atm of N2 or in the presence of excess water. Hydrogenation of (CF3PCP)Ir(L) (L = cod, isoprene) did not produce (CF 3PCP)Ir(H)x but instead afforded the first example of the unusual aryl-bridged bimetallic complex [(μ-1κ2(P,C), 2κ2(P′,C)-CF3PCP)Ir(H)2] 2(μ-CF3PCPH)(μ-H), which has been isolated and crystallographically characterized. Ir(I) pincer complexes (CF 3PCP)Ir(L) (L = MeP(C2F5)2, CO, dfepe (dfepe = (C2F5)2PCH2CH 2P(C2F5)2)) also serve as moderately active aldehyde decarbonylation catalyst precursors for 2-naphthaldehyde with similar activities in diglyme (1.7 TO h-1, 152 °C) and in 1,4-dioxane (0.052 TO h-1, 94 °C). The catalyst resting states are the corresponding five-coordinate carbonyl complexes (CF3PCP) Ir(MeP(C2F5)2)(CO), (CF3PCP)Ir(CO) 2, and [(CF3PCP)Ir(CO)]2(μ-dfepe). DFT studies indicate that the preferred catalyst resting state for alkane dehydrogenation, (CF3PCP)Ir(cod), can be ascribed to the lower steric requirements of the CF3-substituted pincer ligand.
Thermochemical alkane dehydrogenation catalyzed in solution without the use of a hydrogen acceptor
Xu, Wei-Wei,Rosini, Glen P.,Gupta, Mukta,Jensen, Craig M.,Kaska, William C.,Krogh-Jespersen, Karsten,Goldman, Alan S.
, p. 2273 - 2274 (2007/10/03)
(PCP)IrH2 [PCP = η3-C6H3(PBut2) 2-1,3] catalyzes the efficient (several hundred mol product/mol catalyst) dehydrogenation of alkanes under reflux to give the corresponding alkenes and dihydrogen.
