Density functional theoretical calculations

Dichloroethane Didecyldimethylammonium bromide Density function theoretical (calculations)... 

Interest in the preparation of high-spin organic compounds has led to the matrix isolation of polynitrenes, such as 57-61. " These species have been studied primarily by EPR spectroscopy, but increasing use is being made of matrix IR and UV-vis spectroscopy. Density functional theoretical calculations have been used to assign the vibrational spectra that have been observed. Polynitrenes are under active smdy by material scientists interested in the development of organic magnets. 

Density functional theoretical calculations were applied to the formation of internal primary ozonides from three PAHs (pyrene, coronene, and circum-pyrene O Hm) to simulate the atmospheric interaction between ozone and soot. No 1,2,4-trioxolane intermediate was considered in the conversion of the 1,2,3-trioxolane into aromatic epoxides via ring-opened trioxyl diradicals <2005PCA10929>. 

Park JY, Harris D. Construction and assessment of models of CYP2E1 predictions of metabolism from docking, molecular dynamics, and density functional theoretical calculations. J Med Chem 2003 46 1645-1660. 

FIGURE 12.3 Structures of a model intermediate [Cp2ZrMe(C2H4)]+ (left), showing the agostic methyl. The methyl leans over even more at the transition state (right). The results were obtained by Ziegler and coworkers by density functional theoretical calculations. Source From Fan et al., 1995 [65]. Reproduced with permission of the American Chemical Society. 

Electronic Structure of 2,2/-Bipyiidine Organotransition-Metal Complexes. Establishing the Ligand Oxidation Level by Density Functional Theoretical Calculations, C. C. Scarborough, K. Wieghardt, K. Inorganic Chemistry 2011, 50, 9773. 

Hydroxyfurazans exist solely in the hydroxy form. This is in accord with quantum chemical calculations (Scheme 167). Density functional theoretical studies (B3LYP/6-311- -G(2d,p)) indicate that 3-hydroxyfurazan is more stable than the... 

By ab initio MO and density functional theoretical (DPT) calculations it has been shown that the branched isomers of the sulfanes are local minima on the particular potential energy hypersurface. In the case of disulfane the thiosulfoxide isomer H2S=S of Cg symmetry is by 138 kj mol less stable than the chain-like molecule of C2 symmetry at the QCISD(T)/6-31+G // MP2/6-31G level of theory at 0 K [49]. At the MP2/6-311G //MP2/6-3110 level the energy difference is 143 kJ mol" and the activation energy for the isomerization is 210 kJ mol at 0 K [50]. Somewhat smaller values (117/195 kJ mor ) have been calculated with the more elaborate CCSD(T)/ ANO-L method [50]. The high barrier of ca. 80 kJ mol" for the isomerization of the pyramidal H2S=S back to the screw-like disulfane structure means that the thiosulfoxide, once it has been formed, will not decompose in an unimolecular reaction at low temperature, e.g., in a matrix-isolation experiment. The transition state structure is characterized by a hydrogen atom bridging the two sulfur atoms. 

An extensive review of the hetero-Diels-Alder reactions of 1-oxabuta-1,3-dienes has been published. Ab initio calculations of the Diels-Alder reactions of prop-2-enethial with a number of dienophiles show that the transition states of all the reactions are similar and synchronous.Thio- and seleno-carbonyl compounds behave as superdienophiles in Diels-Alder reactions with cyclic and aryl-, methyl-, or methoxy-substituted open-chain buta-1,3-dienes.The intramolecular hetero-Diels-Alder reactions of 4-benzylidine-3-oxo[l,3]oxathiolan-5-ones (100) produce cycloadducts (101) and (102) in high yield and excellent endo/exo-selectivity (Scheme 39). A density functional theoretical study of the hetero-Diels-Alder reaction between butadiene and acrolein indicates that the endo s-cis is the most stable transition structure in both catalysed and uncatalysed reactions.The formation and use of amino acid-derived chiral acylnitroso hetero-Diels-Alder reactions in organic synthesis has been reviewed. The 4 + 2-cycloadditions of A-acylthioformamides as dienophiles have been reviewed. ... 

In 2002, Musaev and coworkers performed the first theoretical investigation of the mechanism with the aid of density functional theory calculations [26]. They first studied the mechanism of cycloisomerization in the absence of a tungsten catalyst, as shown in Scheme 4.14. The D FT calculations showed that the exo-cycloisomerization of 4-pentyn-l-ol via a concerted transition state leading to a five-membered-ring exo product had a high barrier (52.0 kcalmol ) (path a of Scheme 4.14). The pathways leading to a six-membered-ring endo product have also been calculated (paths b and c... 

The dimerization process of [(C5H4Me)(dmpe)Mn=C=CHR]+ to [(C5H4Me) (dmpe)Mn=CCHRCHRC=Mn(dmpe)(C5H4Me)], studied both experimentally and theoretically, was briefly discussed. Density functional theory calculations showed that the dimerization process was favorable when R=H, Me, Ph and C6H4Me) but unfavorable when R = silyl. The calculations also showed that the LUMO of a given dimer consisted of Tc -antibonding character between Mn and Co,... 

No theoretical studies were reported in the previous volume <1996CHEC-11(7)89> for these 5-5 bicyclic systems. Since then a number of computational studies have been carried out. The structure and properties of cyclic sulfites 3a and 3b and thionosulfites 3c and 3d have been reported <2003HAC587, 2005HCA1451>. Density functional theoretical (DFT) calculations using the Becke s exchange with Lee, Yang, and Parr correlation functional (B3LYP/6-31G level) have shown that the cyclic sulfite 3b is more stable than its diastereomer 3a. 

The description of bonding at transition metal surfaces presented here has been based on a combination of detailed experiments and quantitative theoretical treatments. Adsorption of simple molecules on transition metal surfaces has been extremely well characterized experimentally both in terms of geometrical structure, vibrational properties, electronic structure, kinetics, and thermo-chemistry [1-3]. The wealth of high-quality experimental data forms a unique basis for the testing of theoretical methods, and it has become clear that density functional theory calculations, using a semi-local description of exchange and correlation effects, can provide a semi-quantitative description of surface adsorption phenomena [4-6]. Given that the DFT calculations describe reality semi-quantitatively, we can use them as a basis for the analysis of catalytic processes at surfaces. 

The reductive NO chemistry will cover some new developments on the electrophilic reactions of bound nitrosyl with different nucleophiles, particularly the nitrogen hydrides (hydrazine, hydroxylamine, ammonia, azide) and trioxodinitrate, along with new density functional theoretical (DFT) calculations which have allowed to better understand the detailed mechanistic features of these long-studied addition reactions, including the one with OH-. The redox chemistry of other molecules relevant to biochemistry, such as O2, H2O2 and the thiolates (SR-) will also be presented. 

The gas-phase proton affinity of the IV-heterocyclic carbene l-ethyl-3-methyl-imidazol-2-ylidene has been determined as 251.3 4 kcalmol-1 using the kinetic method, a value which makes the carbene one of the strongest bases reported thus far.160 Density functional theory calculations have been carried out at the B3FYP/ 6-31+G(d) level to compare the high experimental value with that estimated theoretically. 

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