Mechanisms of rearrangements in platinacyclobutane chemistry

2020 ◽  
pp. 1-8
Author(s):  
Richard J. Puddephatt
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Activation Energies ◽  
High Activation ◽  
Functional Theory ◽  
Hydride Complexes ◽  
Decomposition Reactions ◽  
Trigonal Bipyramidal ◽  
Mechanisms Of Formation

The mechanisms of formation, decomposition, and isomerisation of platinacyclobutane complexes [PtCl2(C3H6)L2] (L is typically pyridine) are discussed on the basis of density functional theory (DFT). The isomerisation and decomposition reactions occur through 5-coordinate intermediates [PtCl2(C3H6)L] that cannot be directly detected. These 5-coordinate complexes are predicted to have distorted square pyramidal structures, but a pinched trigonal bipyramidal (PTBP) stereochemistry is easily accessible. Both α- and β-elimination from these complexes to give hydride complexes [PtHCl2(C3H5)L] are predicted to have high activation energies. The isomerisation of [PtCl2(C3H6)L2] to the ylide complex [PtCl2{CH(L)CH2CH3)L] is instead predicted to occur after cleavage of a Pt–C bond to give an intermediate that can be considered as a corner platinated cyclopropane, leading to 1,3-hydrogen transfer without a hydridoplatinum intermediate. The reaction of [PtCl2{CH(L)CH2CH3}L] to give the alkene complex [PtCl2(CH2 = CHCH3)L] involves dissociation of the C–L bond followed by a 2,1-hydrogen transfer. The selectivity of related reactions from phenylcyclopropane follows naturally from these mechanisms.

scholarly journals Density Functional Theory Calculations on Copper-Mediated Peroxide Decomposition Reactions: Implications for Jet Fuel Autoxidation

2020 ◽  
Vol 34 (6) ◽  
pp. 7439-7447 ◽  
Author(s):  
Christopher M. Parks ◽  
Ehsan Alborzi ◽  
Simon G. Blakey ◽  
Anthony J. H. M. Meijer ◽  
Mohamed Pourkashanian
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Jet Fuel ◽  
Functional Theory ◽  
Decomposition Reactions ◽  
Peroxide Decomposition

Binuclear O2 activation and hydrogen transfer mechanism for aerobic oxidation of alcohols

2020 ◽  
Vol 10 (7) ◽  
pp. 2183-2192
Author(s):  
Zhiyun Hu ◽  
Hongyu Ge ◽  
Xinzheng Yang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Aerobic Oxidation ◽  
Density Functional Theory Calculations ◽  
Transfer Mechanism ◽  
Functional Theory ◽  
O2 Activation ◽  
Oxidation Of Alcohols

Density functional theory calculations reveal a binuclear O2 activation and hydrogen transfer mechanism with spin-crossovers for aerobic oxidation of alcohols.

THEORETICAL STUDIES ON THE REACTION MECHANISM OF HNCS WITH CH2CH RADICAL

2007 ◽  
Vol 06 (01) ◽  
pp. 1-12 ◽  
Author(s):  
JIAN-HUA XU ◽  
LAI-CAI LI ◽  
YAN ZHENG ◽  
JUN-LING LIU ◽  
XIN WANG
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Main Product ◽  
Reaction Pathways ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Ch Radical

The reaction mechanisms of HNCS with CH 2 CH radical have been investigated by density functional theory (DFT). The geometries and harmonic frequencies of the reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311++G(d,p) level. The results show that the reaction is very complicated. Nine possible reaction pathways were identified. The results show that the most feasible reaction channel is the hydrogen-transfer pathway CH 2 CH + HNCS → IMA1 → TSA1 → CH 2 CHH + NCS . The pathway VIC C-S addition channel ( CH 2 CH + HNCS → TSD5 → IMD4 → TSD9 → CH 2 CHS + CNH ) can also occur easily. Ethene and radical NCS is the main product of the studied reaction, and product P8 ( CH 2 CHS and CNH ) may also be observed. Compared with our previous study on the reaction HNCS + CH 2 CH , the present reaction is easier to proceed.

A density functional theory study of the mechanisms of addition of transition metal oxides ReO3L(L = Cl-, O-, OCH3, CH3) to substituted ketenes

2015 ◽  
Vol 14 (05) ◽  
pp. 1550035 ◽  
Author(s):  
Issahaku Ahmed ◽  
Richard Tia ◽  
Evans Adei
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Metal Complexes ◽  
Oxidation State ◽  
Density Functional ◽  
High Activation ◽  
Functional Theory ◽  
Activation Barriers ◽  
Reaction Energies ◽  
Addition Pathway

Ketenes are excellent precursors for catalytic asymmetric reactions, creating chiral centers mainly through addition across their C = C bonds. Density functional theory (DFT) calculations at the MO6/LACVP* and B3LYP/LACVP* levels of theory were employed in a systematic investigation of the peri-, chemo- and regio-selectivity of the addition of transition metal oxo complexes of the type ReO 3 L ( L = Cl -, O -, OCH 3, CH 3) to substituted ketenes O = C = C ( CH 3)(X) [ X = CH 3, H , CN , Ph ] with the aim of elucidating the effects of substituents on the mechanism of the reactions. The [2 + 2] addition pathway across the C = C or C = O (depending on the ligand) is the most preferred in the reactions of dimethyl ketene with all the metal complexes studied. The [2 + 2] pathway is also the most preferred in the reactions of ReO 3 Cl with all the substituted ketenes studied except when X = Cl . Thus of all the reactions studied, it is only the reaction of ReO 3 Cl with O = C = C ( CH 3)( Cl ) that prefers the [3 + 2] addition pathway. Reactions of dimethyl ketene with ReO 3 L favors addition across C = O bonds of the ketene when L = O - and CH 3 but favors addition across C = C bonds when L = OCH 3 and Cl . In the reactions of ReO 3 Cl with substituted ketenes, addition across C = O bonds is favored only when X = H while addition across C = C bonds is favored when X = CH 3, Cl , Ph , CN . The reactions of dimethyl ketene with ReO 3 L will most likely lead to the formation of an ester precursor in each case. A zwitterionic intermediate is formed in the reactions except in the reactions of [Formula: see text]. The order in the activation energies of the reactions of dimethyl ketenes with the metal complexes ReO 3 L with respect to changing ligand L is O - < CH 3 O - < Cl - < CH 3 while the order in reaction energies is CH 3 < CH 3 O - < O - < Cl -. For the reactions of substituted ketenes with ReO 3 Cl , the order in activation barriers is CH 3 < Ph < CN < Cl < H while the reaction energies follow the order Cl < CH 3 < H < Ph < CN . In the reactions of dimethyl ketenes with ReO 3 L , the trend in the selectivity of the reactions with respect to ligand L is Cl - < CH 3 O - < CH 3 < O - while the trend in selectivity is CH 3 < CN < Cl < Ph in the reactions of ReO 3 Cl with substituted ketenes. It is seen that reactions involving a change in oxidation state of metal from the reactant to product have high activation barriers while reactions that do not involve a change in oxidation state have low activation barriers. For both [3 + 2] and [2 + 2] additions, low activation barriers are obtained when the substituent on the ketene is electron-donating while high activation barriers are obtained when the substituent is electron-withdrawing.

scholarly journals Mechanism of Reactions of 1-Substituted Silatranes and Germatranes, 2,2-Disubstituted Silocanes and Germocanes, 1,1,1-Trisubstituted Hyposilatranes and Hypogermatranes with Alcohols (Methanol, Ethanol): DFT Study

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2803 ◽  
Author(s):  
Denis Chachkov ◽  
Rezeda Ismagilova ◽  
Yana Vereshchagina
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical ◽  
Density Functional ◽  
Activation Energies ◽  
Functional Theory ◽  
Gibbs Energies ◽  
The Density Functional Theory ◽  
Lower Activation ◽  
One Step ◽  
Intramolecular Hydrogen

The mechanism of reactions of silatranes and germatranes, and their bicyclic and monocyclic analogues with one molecule of methanol or ethanol, was studied at the Density Functional Theory (DFT) B3PW91/6-311++G(df,p) level of theory. Reactions of 1-substituted sil(germ)atranes, 2,2-disubstituted sil(germ)ocanes, and 1,1,1-trisubstituted hyposil(germ)atranes with alcohol (methanol, ethanol) proceed in one step through four-center transition states followed by the opening of a silicon or germanium skeleton and the formation of products. According to quantum chemical calculations, the activation energies and Gibbs energies of activation of reactions with methanol and ethanol are close, their values decrease in the series of atranes–ocanes–hypoatranes for interactions with both methanol and ethanol. The reactions of germanium-containing derivatives are characterized by lower activation energies in comparison with the reactions of corresponding silicon-containing compounds. The annular configurations of the product molecules with electronegative substituents are stabilized by the transannular N→X (X = Si, Ge) bond and different intramolecular hydrogen contacts with the participation of heteroatoms of substituents at the silicon or germanium.

scholarly journals Copper mediated decyano decarboxylative coupling of cyanoacetate ligands: Pesci versus Lewis acid mechanism

2015 ◽  
Vol 44 (19) ◽  
pp. 9230-9240 ◽  
Author(s):  
Jiawei Li ◽  
George N. Khairallah ◽  
Vincent Steinmetz ◽  
Philippe Maitre ◽  
Richard A. J. O'Hair
Keyword(s):  
Mass Spectrometry ◽  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Ion Trap ◽  
Functional Theory ◽  
Decomposition Reactions ◽  
Decarboxylative Coupling ◽  
Gas Phase Ion ◽  
Sequential Decomposition

A combination of gas-phase ion trap multistage mass spectrometry (MSn) experiments and density functional theory (DFT) calculations have been used to examine the mechanisms of the sequential decomposition reactions of copper cyanoacetate anions, [(NCCH2CO2)2Cu]−.

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