Quantum chemical study of the

Da Silva, G. Chen, C.-C. Bozzelli, J. W. Quantum chemical study of the thermal decomposition of o-quinone methide (6-methylene-2,4-cyclohexadien-l-one). J. Phys. Chem. A 2007, 111, 7987-7994. 

E. Broclawik, J. Haber, Quantum chemical study of the reaction of ammonia with transient oxygen species, J. Mol. Catal., 1993, 82, 353. 

Consider, for example, the well-studied reaction between C+ and NH3, for which one set of products consists of the ion CH2N+ + H. But what is the structure of the product ion Based on detailed quantum chemical studies of the very complex potential surface, it is likely that two isomers are produced initially—the linear HCNH+ ion and the T-shaped H2NC+form89—although it is also possible that the latter form can subsequently isomerize via a unimolecular path into the more stable... 

Voityuk AA, MichelBeyerle ME, Rosch N (1997) Protonation effects on the chromophore of green fluorescent protein. Quantum chemical study of the absorption spectrum. Chem Phys... 

Martin, M., F. Sanz, M. Campillo, L. Pardo, J. Perez, and J. Turmo. 1983a. Quantum Chemical Study of the Molecular Patterns of MAO Inhibitors and Substrates. Int. J. Quant. Chem. 23, 1627. 

The elusive nature of binary gold carbonyls - known only from earlier matrix-isolation studies and from CO adsorbed on surfaces of bulk gold - has prompted quantum-chemical studies of the hypothetical species Au(CO) with n = 1, 2, 3. Two independent investigations (on the HF and ab initio level, MP2, CCSD(T)) have consistently... 

C. Emmeluth, V. Dyczmons, T. Kinzel, P. Botschwina, M. A. Suhm, and M. Yanez, Combined jet relaxation and quantum chemical study of the pairing preferences of ethanol. Phys. Chem. 

The desired accuracy of the thermodynamic and kinetic activation parameters in systems of commercial interest has not yet been achieved in quantum chemical studies of the hydroformylation. Nevertheless, theoretical investigations have cast considerable light on this still little understood catalytic reaction. 

Photoelectron.—n-Orbital energies appear to be unsuitable to discern the aromatic nature of phospholes (120) due to combined nn and ttn interactions. It is concluded that n conjugative and P-Cw hyperconjugative interactions stabilize the phos-phole system relative to the interrupted cw-butadiene and phosphorus subunits, and that the p.e. spectrum can be interpreted in favour of an aromatic phosphole ring.143 Other workers have discussed144 and reviewed145 this aromaticity problem, and there has been a quantum-chemical study of the aromatic nature of phosphorus hetero-cycles.144 The p.e. spectrum of the ylide (121) contains peaks at 6.19, 8.32, and... 

N.U. Zhanpeisov et al., Cluster quantum chemical study of the interaction of dimethyl methylphosphonate with magnesium oxide. J. Phys. Chem. 98, 10032-10035 (1994)... 

Z. Czyznikowska, R. Zalesny, P. Cysewski, Quantum chemical study of the nature of stacking interactions of 2-oxo-adenine with native B-DNA purine bases. Pol. J. Chem. 82, 2269-2279 (2008)... 

Beran S (1984) Quantum chemical study of the effect of the structural characteristics of zeolites on the properties of their bridging hydroxyl groups, J Mol Catal 26 31—36... 

Zhanpeisov NU, Zhidomirov GM, Yudanov IV, Klabunde KJ (1994) Cluster Quantum Chemical Study of the Interaction of Dimethyl Methylphosphonate with Magnesium Oxide, J Phys Chem 98 10032-10035... 

Diaz, N., Suarez, D., and Merz, K.M., Jr. (2001) Molecular dynamics simulation of the mononuclear zinc-P-lactomase from Bacciluscereus complexed with benzylpenicillin and quantum chemical study of the reaction mechanism, /. Am. Chem. Soc. 123, 9867-9879. 

M. Brynda, L. Gagliardi, P.-O. Widmark, P. P. Power, and B. O. Roos, A Quantum Chemical Study of the Quintuple Bond Between Two Chromium Centers in... 

A series of papers by Beran et al. (102-112) was devoted to quantum-chemical studies of the cationic forms of zeolites using cluster models and the CNDO/2 technique. As a rule, cyclic clusters consisting of four or six T04 (T = Si, Al) tetrahedra were considered as models for four-membered (S, sites) and six-membered (S S, and S,r sites) oxygen windows in the zeolite structures. 

Mechanism of the nitration of benzimidazoles has not been studied much, but there are weighty arguments to conclude that they are nitrated as conjugated acids [51, 103], Kinetic studies of the nitration of benzimidazole and some of its 2-substituted derivatives have confirmed that the protonated form is involved in the process [104], Recent results of quantum chemical studies of the nitration of ben-zazoles indicate the importance of the protonated benzimidazolium cations in the nitration process [43],... 

A great number of publications deal with the reaction of nitration [7-20], At the same time, volumes literature on nitro heterocycles has not been systematized until the present time. Direct nitration of some five-membered heterocycles such as pyrroles, furans, thiophenes, pyrazoles, imidazoles, and thiazoles has been discussed by Katritzky [21, 22], Some synthetic routes to nitrated six-membered nitrogen-containing aromatic heterocycles [23], as well as the nitration of oxo-pyrimidines and -imidazoles [24], and quantum-chemical studies of the nitration of benzazoles [25] have been reported. 

The importance of 1,3-dipolar cycloadditions (1,3-DC) in the realm of heterocyclic synthesis is widely documented and recent results concerning the intramolecular version of this methodology, including reactions with nitrile oxides and nitrones for access to isoxazole derivatives, have been reviewed <07T12247>. A quantum chemical study of the Lewis acid effect on the cycloaddition of benzonitrile oxide to propyne has been reported evidencing a small influence on the outcome of the reaction <07T5251>. 

We undertook a quantum chemical study of the protonation of monocyclic and benzannulated five-membered heterocyclic systems with one heteroatom (03KGS38). The initial calculations, carried out by the semi-empirical CNDO/2 method (81ZOR1129), gave values for the differences in energy of the cations formed on protonation of the a- and yS-positions iAEa-p) that corresponded with the available experimental data on the sequence of change in positional selectivity furan > thiophene > pyrrole. However, the place of selenophene between thiophene and pyrrole in this series predicted by these calculations was contradicted by the experimental results obtained later (95JHC53). The results of calculations by the MNDO and PM3 methods also did not fit the experimental data, possibly linked with poor parametrization for selenium atom (97M12). 

Bacskay, G. B. and Craw, J. S., Quantum chemical study of the trimethylamine-hydrogen chloride complex, Chem. Phys, Lett. 221, 167-174 (1994). 

Miscellaneous Reactions of Phosphines. The effects of substituents at phosphorus on the basicity and donor properties of phosphines have continued to attract the attention of the theoretical chemists. Among recent papers are a quantum chemical study of the protonation of phenylphosphine and its... 

A quantum chemical study of the mechanism of the cis-trans photochemical isomerization in retinal like protonated Schiff bases uses the model compound 1-imino-2.3-pentadiene23. The lowest excited state is B like but the second A like state is particularly labile photochemically. The photoisomerization of all trans-retinal has been studied in a variety of organic solvents and organized media232 The structure of the isomers involved in the photoisomerization of retinoic acid and photoprotective effects in model physiological solutions have been determined233. picosecond time-resolved absorption study of... 

Andres, J., Silla, E., Tapia, O. Quantum-chemical studies of the energy hypersurface for the Meyer-Schuster rearrangement. STO-3G calculation of minimum-energy paths. Intermolecular mechanism. Chem. Phys. Lett. 1983, 94,193-197. 

A conformational analysis of naproxen anion and monensin sodium has been performed by the use of the /hc couplings. Especially extensive use of these couplings has been made by the authors in the case of the latter compound. They concluded that the conformation of monoensin in solution is very close to that in crystals. Further examples of the application of vicinal proton-carbon couplings in the conformational analysis of compounds include the NMR and quantum-chemical study of the stereochemistry of spiroepoxides obtained by oxidation of (Z)-3-arylidene-l-thioflavan-4-ones performed by Toth et and the elucidation of the structure of isomalyngamides A and B isolated from a collection of the cyanobacterium Lyngbya majuscula from Hawaiian waters by Kan et... 

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