107-25-5Relevant articles and documents
Thermally Stable Half-Sandwich Benzhydryl Ln(II) (Ln = Sm, Yb) Complexes Supported by Sterically Demanding Carbazolyl and Fluorenyl Ligands
Selikhov, Alexander N.,Shavyrin, Andrey S.,Cherkasov, Anton V.,Fukin, Georgy K.,Trifonov, Alexander A.
, p. 4615 - 4624 (2019)
A series of new isolable and thermally stable half-sandwich Ln(II) benzhydryl complexes coordinated by the sterically demanding ligands tert-butylcarbazol-9-yl [tBu4Carb]Ln[(p-tBu-C6H4)2CH](L) (Ln = Sm, L = DME (4); Ln = Yb, L = DME (5); Ln = Yb, L = TMEDA (6)) and 2,7-di-tert-butyl-fluoren-9-trimethylsilylyl [2,7-tBu2-9-Me3Si-C13H6]Yb[(p-tBu-C6H4)2CH](DME) (7) were synthesized by the alkane elimination reaction of [(p-tBu-C6H4)2CH]2Ln(Ln) (Ln = Sm, Yb) with tBu4CarbH and 2,7-tBu2-9-Me3Si-C13H7. X-ray analysis revealed that in 4, 5, and 7 the benzhydryl ligand is coordinated to the metal ion in an ν3 coordination mode, while in 6 it is ν1-bound. The type of coordination of the benzhydryl ligands in diamagnetic 5-7 is retained in their C6D6 solutions. Complexes 4-7 demonstrated unprecedented thermal stability and do not undergo decomposition after heating their solutions in C6D6 or toluene at 100 °C for 72 h. The reactions of [tBu4Carb]Ln[(p-tBu-C6H4)2CH](DME) (Ln = Sm (4), Ln = Yb (5)) with an excess of DME led to the formation of the symmetrical bis(carbazolyl) complex products [tBu4Carb]2Ln(DME)4 (Ln = Sm (8), Yb (9)) isolated in the form of separated ion pairs.
Snyder et al.
, p. 2037 (1966)
Decompositions of Ionized Isopropyl Methyl Ether: Complex-Mediated and Direct Processes in Unimolecular Dissociations
McAdoo, David J.,Traeger, John C.,Hudson, Charles E.,Griffin, Lawrence L.
, p. 1524 - 1530 (1988)
Methane and methyl losses from ionized isopropyl methyl ether (1) were characterized to improve our understanding of ion-neutral-complex-mediated dissociations in the gas phase.Photoionization appearance energies demonstrate that the onsets for the two reactions differ by only 2+/-1 kJ mol-1, consistent with the two processes being related by a common bond cleavage.Isotope effects confirm that the transition states for bond scission to form the complex and subsequent hydrogen transfer to form methane are at very similar energies.Loss of methane becomes insignificant 20-30 kJ mol-1 above its onset, whereas loss of methyl increases rapidly for at least 100 kJ mol-1 above threshold.From this it is concluded that the decompositions of 1 are complex-mediated near threshold but shift to a direct mechanism at higher energies, i. e., that decomposition is ion-neutral-complex-mediated over only a narrow range of energies just above threshold.
Gaseous 1-Methyl-1-oxoniacycloalkanes as Stable Intermediates on the C3H7O+ and C4H9O+ Potential Energy Surfaces
Angelini, Giancarlo,Speranza, Maurizio
, p. 1217 - 1219 (1983)
The nature and the isomeric distribution of the neutral products obtained from the gas-phase attack of CH5+, C2H5+, and CH3FCH3+ ions on cyclic CnH2nO (n = 2, 3, and 4) ethers provide the first experimental evidence in favour of 1-methyl-1-oxoniacyclopropane and 1-methyl-1-oxoniacyclobutane as stable intermediates on the corresponding potential energy surface.
SYNTHESIS OF 2-CHLOROETHYL DIAZOACETATE AND STUDY OF ITS CARBENIC DECOMPOSITION
Shapiro, E.A.,Lun'kova, G.V.,Dol'gii, I.E.,Nefedov, O.M.
, p. 2317 - 2322 (1984)
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Phosphine-Catalyzed Vinylation at Low Acetylene Pressure
Bienewald, Frank,Comba, Peter,Hashmi, A. Stephen K.,Menche, Maximilian,Rominger, Frank,Schafer, Ansgar,Schaub, Thomas,Sitte, Nikolai A.,Tuzina, Pavel
, p. 13041 - 13055 (2021/09/18)
The vinylation of various nucleophiles with acetylene at a maximum pressure of 1.5 bar is achieved by organocatalysis with easily accessible phosphines like tri-n-butylphosphine. A detailed mechanistic investigation by quantum-chemical and experimental methods supports a nucleophilic activation of acetylene by the phosphine catalyst. At 140 °C and typically 5 mol % catalyst loading, cyclic amides, oxazolidinones, ureas, unsaturated cyclic amines, and alcohols were successfully vinylated. Furthermore, the in situ generation of a vinyl phosphonium species can also be utilized in Wittig-type functionalization of aldehydes.
Chloro and alkyl rare-earth complexes supported by ansa-Bis(amidinate) ligands with a rigid o-phenylene linker. Ligand steric bulk: A means of stabilization or destabilization?
Tolpygin, Aleksei O.,Shavyrin, Andrei S.,Cherkasov, Anton V.,Fukin, Georgy K.,Trifonov, Alexander A.
, p. 5405 - 5413 (2012/11/13)
ansa-Bis(amidinate) ligands with a rigid o-phenylene linker, C 6H4-1,2-{NC(tBu)N(2,6-R2C6H 3)H}2 (R = Me (1), iPr (2)), were successfully employed for the synthesis of rare-earth chloro and alkyl species. The reaction of dilithium derivatives of 1 and 2 with LnCl3 (Ln = Y, Lu) afforded the monomeric bis(amidinate) chloro lanthanide complexes [C6H 4-1,2-{NC(tBu)N(2,6-R2C6H3)} 2]Y(THF)(μ-Cl)2Li(THF)2 (R = Me (3), iPr (5)) and [C6H4-1,2-{NC(tBu)N(2,6-Me2C 6H3)}2]LuCl(THF)2 (4). Bis(amidinate) ligands in complexes 3 and 4 are coordinated to the metal atoms in a tetradentate fashion, while the bulkier ligand in 5 is tridentate. The alkane elimination reactions of 1 and 2 with equimolar amounts of (Me 3SiCH2)3Ln(THF)2 (Ln = Y, Lu) allowed us to obtain the monoalkyl complexes [C6H4-1,2- {NC(tBu)N(2,6-R2C6H3)}2]Ln(CH 2SiMe3)(THF)n (Ln = Y, R = Me, n = 1 (6); Ln = Lu, R = Me, n = 1 (7); Ln = Y, R = iPr, n = 2 (8)). The kinetics of thermal decomposition of complexes 6-8 were measured, and for 6 the activation energy was obtained from the temperature dependence of the rate constants (E a = 67.0 ± 1.3 kJ/mol). Complexes 6 and 7 turned out to be inert toward H2 and PhSiH3. Surprisingly, complex 8 was inert toward H2 and PhSiH3 but rapidly cleaved C-O bonds of DME. The reaction resulted in the formation of the methoxy complex {[C 6H4-1,2-{NC(tBu)N(2,6-iPr2C6H 3)}2]Y(μ2-OMe)]}2(μ 2-DME) (9) and methyl vinyl ether.
