4741-94-0Relevant academic research and scientific papers
C-H Bond Activations by Monoanionic, PNP-Supported Scandium Dialkyl Complexes
Levine, Daniel S.,Tilley, T. Don,Andersen, Richard A.
, p. 4647 - 4655 (2015/10/28)
A series of scandium dialkyl complexes, (PNP)ScR2 (R = neopentyl, trimethylsilylmethyl), supported by the monoanionic, chelating PNP ligand (2,5-bis(dialkylphosphinomethyl)pyrrolide; alkyl = cyclohexyl, tert-butyl) was synthesized, and the reactivities of these complexes toward simple hydrocarbons was investigated. The scandium-carbon bonds undergo σ-bond metathesis reactions with hydrogen, and these complexes are catalysts for the hydrogenation of alkenes. Reactions with primary amines led to formation of amido complexes that undergo cyclometalation via σ-bond metathesis, without involvement of an imido complex intermediate. A variety of carbon-hydrogen bonds are also activated, including sp-, sp2-, and sp3-C-H bonds (intramolecularly in the latter case).
Exchange Reactions of Alkanes containing Quaternary Carbon Atoms over Supported Metal Catalysts
Brown, Ronald,Kemball, Charles
, p. 2159 - 2172 (2007/10/02)
A comparison has been made of the exchange reactions with deuterium of 2,2-dimethylpropane (DMP), 2,2,3,3-tetramethylbutane (TMB) and 2,2,4,4-tetramethylpentane (TMP) over supported catalysts containing iridium, palladium, platinum or rhodium at temperatures in the neighbourhood of 400 K.Reactions were followed mass-spectrometrically and products were also examined by deuterium n.m.r. spectroscopy.Four processes or mechanisms were found to contribute to different extents with the various hydrocarbon-metal systems.These were (I) stepwise exchange, (II) methyl-group exchange, and more general multiple exchange involving (III) αγ-diadsorbed or (IV) αδ-diadsorbed intermediates.Some isomerisation of TMP was observed to occur simultaneously with exchange with the TMP-rhodium system.
Intermolecular activation of C-D bonds in benzene-d6 by trans-neopentyl(trifluoromethanesulfonato)bis(trimethyl-phosphine) platinum (II)
Brainard, Robert L.,Rodger Nutt,Randall Lee,Whitesides, George M.
, p. 2379 - 2386 (2008/10/08)
trans-(Me3P)2Pt(CH2C(CH3) 3)(SO3CF3) (L2PtNpTf, 1) reacts with benzene-d6 at 133°C and gives trans-(Me3P)2Pt(C6D5)(SO 3CF3) (2) and neopentane-d1 as the major products. When this reaction is carried out in concentrated solutions ([1]0 ≥ 0.04 M), small quantities of neopentane-d0 (8-17%) and 1,1-dimethylcyclopropane (1-3%) are also detected; larger quantities of neopentane-d0 are produced (32-45%) when the initial concentration of 1 is low ([1]0 = 0.01-0.03 M). The rate of reaction is decreased by the addition of Bu4N+Tr- and increased by the addition of Bu4N+BF4-. A competitive kinetic isotope effect was estimated by allowing 1 to react with C6D5H and comparing the relative yields of neopentane-d0 and neopentane-d1: kH/kD is large, but its quantitative value is uncertain because of experimental ambiguities. The mechanism for this reaction seems to involve generation of L2PtNp+ as an essential intermediate. This intermediate appears to react with benzene by direct oxidative addition of a C-H bond, but electrophilic attack on the benzene ring cannot be rigorously excluded.
