scholarly journals Substituent effects in the decarboxylation reactions of coordinated arylcarboxylates in dinuclear copper complexes, [(napy)Cu2(O2CC6H4X)]+

2017 ◽  
Vol 23 (6) ◽  
pp. 351-358 ◽  
Author(s):  
Qiuyan Jin ◽  
Jiaye Li ◽  
Alireza Ariafard ◽  
Allan J Canty ◽  
Richard AJ O’Hair
Keyword(s):  
Density Functional Theory ◽  
Transition State ◽  
Density Functional ◽  
Copper Complexes ◽  
Substituent Effects ◽  
Density Functional Theory Calculations ◽  
Molecular Formula ◽  
Binuclear Complexes ◽  
Aryl Group ◽  
Functional Theory

A combination of gas-phase ion trap mass spectrometry experiments and density functional theory (DFT) calculations have been used to examine the role of substituents on the decarboxylation of 25 different coordinated aromatic carboxylates in binuclear complexes, [(napy)Cu2(O2CC6H4X)]+, where napy is the ligand 1,8-naphthyridine (molecular formula, C8H6N2) and X = H and the ortho ( o), meta ( m) and para ( p) isomers of F, Br, CN, NO2, CF3, OAc, Me and MeO. Two competing unimolecular reaction pathways were found: decarboxylation to give the organometallic cation [(napy)Cu2(C6H4X)]+ or loss of the neutral copper benzoate to yield [(napy)Cu]+. The substituents on the aryl group influence the branching ratios of these product channels, but decarboxylation is always the dominant pathway. Density functional theory calculations reveal that decarboxylation proceeds via two transition states. The first enables a change in the coordination mode of the coordinated benzoate in [(napy)Cu2(O2CC6H4X)]+ from the thermodynamically favoured O, O-bridged form to the O-bound form, which is the reactive conformation for the second transition state which involves extrusion of CO2 with concomitant formation of the CO2 coordinated organometallic cation, [(napy)Cu2(C6H4X)(CO2)]+, which then loses CO2 in the final step to yield [(napy)Cu2(C6H4X)]+. In all cases the barrier is highest for the second transition state. The o-substituted benzoates show a lower activation energy than the m-substituted ones, while the p-substituted ones have the highest energy, which is consistent with the experimentally determined normalised collision energy required to induce fragmentation of [(napy)Cu2(O2CC6H4X)]+.

Substituent Effects on Ultraviolet Absorption Spectra of 5-Substituted Nb-Acetyl-1-methoxytryptamines Studied by Density Functional Theory Calculations

Heterocycles ◽  
2007 ◽  
Vol 73 (1) ◽  
pp. 275 ◽  
Author(s):  
Kunihiro Tokumura ◽  
Kenta Imai ◽  
Akio Hayashi ◽  
Tomonori Ida ◽  
Masanori Somei
Keyword(s):  
Density Functional Theory ◽  
Absorption Spectra ◽  
Density Functional ◽  
Substituent Effects ◽  
Density Functional Theory Calculations ◽  
Ultraviolet Absorption ◽  
Functional Theory

scholarly journals The Mechanism of the Propagation in the Anionic Polymerization of Polystyryllithium in Non-Polar Solvents Elucidated by Density Functional Theory Calculations. A Study of the Negligible Part Played by Dimeric Ion-Pairs under Usual Polymerization Conditions

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1022
Author(s):  
Hideo Morita ◽  
Marcel Van Beylen
Keyword(s):  
Density Functional Theory ◽  
Transition State ◽  
Anionic Polymerization ◽  
Density Functional ◽  
Ion Pairs ◽  
Density Functional Theory Calculations ◽  
Dft Method ◽  
Functional Theory ◽  
Elementary Processes ◽  
Rate Of Reaction

The elementary processes occurring in the anionic polymerization of styrene with dimerically associated polystyryllithium (propagation during the anionic polymerization of dimeric polystyryllithium) in the gas phase and cyclohexane were studied using MX062X/6-31+G(d), a recently developed density functional theory (DFT) method and compared with the polymerization of styrene with non-associated polystyryllithium, which was described in a previous study. The most stable transition state in the reaction of styrene with dimeric polystyryllithium has a structure in which the side chains of styrene and the two chain end units of polystyryllithium are located in the same direction around the Li atom near the reactive site. The relative enthalpy for this transition state in cyclohexane is 28 kJ·mol−1, which is much lower than that for the reaction of non-associated polystyryllithium (51 kJ·mol−1). However, the relative free energy (which determines the rate constant) for the former is 93 kJ·mol−1, which is greater than that for the latter by 7 kJ·mol−1, indicating that the latter reaction (reaction with non-associated polystyryllithium) is advantageous over the former (reaction with dimeric polystyrylllithium). Their rates of reaction are also affected by initiator concentrations; in the case of reactions with low initiator concentrations, from which high molecular weight polymers are usually obtained, the rate of reaction corresponding to non-associated polystyryllithium is much larger than that corresponding to dimeric polystyryllithium.

Application of periodic density functional theory calculations for exploring copper(II) coordination effects on the mesophase behavior of p-n-alkoxybenzoic acids

2019 ◽  
Vol 18 (01) ◽  
pp. 1950006 ◽  
Author(s):  
Li-Fen Wang ◽  
Cheng-Xian You
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Valuable Insight ◽  
Binuclear Complexes ◽  
Functional Theory ◽  
Bidentate Coordination ◽  
Smectic C ◽  
Cu Complexes ◽  
Insight Into

Copper(II) benzoates ([Formula: see text]OBA-Cu) with various terminal alkoxy carbon numbers, [Formula: see text]–12, were prepared from [Formula: see text]-[Formula: see text]-alkoxy benzoic acids (nOBAs). Fourier transform infrared (IR) experiments suggested that dimerization through copper(II) chelating bidentate coordination created [Formula: see text]OBA-Cu with a linear rod-like structure, similar to the hydrogen-bonded structure of its parent [Formula: see text]OBA. However, the coordination structure of [Formula: see text]OBA-Cu changed during heating. Periodic density functional theory calculations provided valuable insight into the possible arrangement of the parent and copper(II)-coordinated [Formula: see text]OBAs. The formation of binuclear complexes between two adjacent [Formula: see text]OBA-Cu dimers forced [Formula: see text]OBA-Cu to arrange itself in a layer and exhibit smectic A mesophase. Accordingly, four types of IR stretching absorption of benzoyl carbonyl were observed in binuclear [Formula: see text]OBA-Cu complexes, replacing the original symmetric and asymmetric vibrations of benzoyl carboxylate in chelating bidentate coordination. The lateral association by [Formula: see text]–[Formula: see text] interactions between adjacent parent [Formula: see text]OBA dimers preferred a progressive smectic C arrangement. The origin of the odd–even effect was understood from the consideration of the molecular structure.

scholarly journals Prediction of the [4 + 2]- and [5 + 4]-cycloaddition reactions in zig-zag carbon nanotubes via an ambimodal transition state: density functional theory calculations

RSC Advances ◽  
2020 ◽  
Vol 10 (19) ◽  
pp. 11111-11120
Author(s):  
Akanksha Ashok Sangolkar ◽  
Ravinder Pawar
Keyword(s):  
Carbon Nanotubes ◽  
Density Functional Theory ◽  
Transition State ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
State Density ◽  
Dft Study ◽  
Cycloaddition Reactions ◽  
Functional Theory

A DFT study has been performed to unveil the ambimodal reaction in H-terminated CNTs.

Electronic or steric effects: Detailed DFT investigations of titanium amino based Kaminsky type olefin catalysts

2018 ◽  
Author(s):  
Jörg Saßmannshausen
Keyword(s):  
Density Functional Theory ◽  
Strong Correlation ◽  
Density Functional ◽  
Steric Effects ◽  
Aryl Group ◽  
Functional Theory

We report detailed Density Functional Theory (DFT) investigations of a series of structurally similar titanium (IV) chelating σ-aryl catalysts. Particular attention was paid to the electronic charges of the Ti, C ipso of the substituted aryl group and the benzylic CH<sub>2</sub> and C<i><sub>ipso</sub></i> atoms. The Bader and NBO derived charges were compared with the recently reported polymerisation results by Chan. We found a strong correlation between the relative energies of one of the computed isomers and the activity of the catalyst. Neither NBO nor Bader charges could be convincingly correlated to the observed activity.

Is a Non-Transition Element Nitride Ferromagnet Ever Achievable? Indication of the N-N Pairing Instability

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1525-1531 ◽  
Author(s):  
Wojciech Grochala
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Transition Element ◽  
Density Functional Theory Calculations ◽  
Functional Theory

The enthalpy of four polymorphs of CaN has been scrutinized at 0 and 100 GPa using density functional theory calculations. It is shown that structures of diamagnetic calcium diazenide (Ca2N2) are preferred over the cubic ferromagnetic polymorph (CaN) postulated before, both at 0 and 100 GPa.

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