F:Flammable;
592-41-6Relevant articles and documents
Role of Defects in Radiation Chemistry of Crystalline Organic Materials. 3. Geometrical and Electronic Structures of Alkene Radical Anion and Cation in Alkene/n-Alkane Mixed Crystals As Studied by ESR Spectroscopy
Matsuura, Kaoru,Muto, Hachizo,Nunome, Keichi
, p. 9481 - 9487 (1991)
An ESR study has been made in order to elucidate the electronic structures of alkene radical anion and cation, the former radical being first detected in the hexene/n-hexane mixed crystals irradiated at 4.2 K along with the cation.The present work extended to the hexene and butene isomers has resulted in evidence that both anions with vinylene and vinylidene groups have pyramidal structures with ?-character, which differ from the planar or twisted structures of corresponding cations.The proton hyperfine couplings of their anions were only about one-third as large asthose of the cations: A(two α-H) = 0.45, 0.1, -0.25 mT; a(two pairs of β-H) = 1.38 and 0.56 mT for the 3-hexene anion, and a(two α-H) = 1.3 mT and a(two pairs of β-H) = 4.6 and 2.9 mT for the cation.The differences in the geometrical structures and in the sizes of the proton couplings of the anion and cation radicals were discussed on the basis of a simple molecular orbital calculation.It has been found that the anion is stabilized by admixing 2s;C atomic orbitals (AO) with a lower core integral than 2p;C AO to the unpaired electron orbital and that the small β-proton couplings mainly originate from low extent of hyperconjugation due to a wide energy separation of C=C ?-antibonding and C-H pseudo-?-bonding orbitals.
LIGANDS FOR PRODUCTION OF 1-HEXENE IN CHROMIUM ASSISTED ETHYLENE OLIGOMERIZATION PROCESS
-
Paragraph 0054-0056, (2022/01/12)
Catalyst compositions and processes for the oligomerization of ethylene to 1-hexene are described. The catalyst composition includes a triamino bisphospino (NPNPN) ligand system with specific phosphorous and nitrogen ligands. The terminal nitrogen atoms include linear alkyl hydrocarbons that differ in the number of carbon atoms by 3.
Precursor Nuclearity and Ligand Effects in Atomically-Dispersed Heterogeneous Iron Catalysts for Alkyne Semi-Hydrogenation
Faust Akl, Dario,Ruiz-Ferrando, Andrea,Fako, Edvin,Hauert, Roland,Safonova, Olga,Mitchell, Sharon,López, Núria,Pérez-Ramírez, Javier
, p. 3247 - 3256 (2021/05/31)
Nanostructuring earth-abundant metals as single atoms or clusters of controlled size on suitable carriers opens new routes to develop high-performing heterogeneous catalysts, but resolving speciation trends remains challenging. Here, we investigate the potential of low-nuclearity iron catalysts in the continuous liquid-phase semi-hydrogenation of various alkynes. The activity depends on multiple factors, including the nuclearity and ligand sphere of the metal precursor and their evolution upon interaction with the mesoporous graphitic carbon nitride scaffold. Density functional theory predicts the favorable adsorption of the metal precursors on the scaffold without altering the nuclearity and preserving some ligands. Contrary to previous observations for palladium catalysts, single atoms of iron exhibit higher activity than larger clusters. Atomistic simulations suggest a central role of residual carbonyl species in permitting low-energy paths over these isolated metal centers.
