Density functional theoretical

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. 

Kushto, G. R, Andrews, L., 1999, Infrared Spectroscopic and Density Functional Theoretical Investigation of the Reaction Products of Laser-Ablated Zr, Hf, and Th Atoms With Nitric Oxide , J. Phys. Chem. A, 103, 4836. 

Venturini, A., Joglar, J., Fustero, S., Gonzalez, J., 1997, Diels-Alder Reactions of 2-Azabutadienes With Aldehydes Ab Initio and Density Functional Theoretical Study of the Reaction Mechanism, Regioselectivity, Acid Catalysis, and Stereoselectivity , J. Org. Chem., 62, 3919. 

Gosh, A., J. Almlof, and L. Que Jr. 1994. Density Functional Theoretical Study of Oxo(porphyroinato)iron(IV) Complexes, Models of Peroxidase Compounds I and II. J. Phys. Chem. 98, 5576. 

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. ... 

Computational studies in the field of imidazo[2,l-f>]thiazoles are still lacking. The results of some semiempirical (AMI, PM3) (90MI1), ab initio (93MI1), and density functional theoretical (95MI1) investigations (96UP2) are also given in Table VI. 

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

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. 

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. 

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. 

Ab initio and density functional theoretical studies of the 4 + 2-cycloaddition of 2-azabutadiene with formaldehyde predict a concerted reaction that agrees well with experimental evidence.184 The azadiene A-plienyl-l-aza-2-cyanobuta-l,3-diene reacts with electron-rich, electron-poor, and neutral dipolarophiles under mild thermal conditions.185 5,6-Diliydro-4//-1,2-oxazines have been shown to be usefiil as synthon equivalents of 2-cyano-l-azabuta-1,3-dienes.186 The intramolecular Diels-Alder reaction of 1-aza-l,3-butadienes (106) can be activated by a 2-cyano substituent (Scheme 37).187 Stereoselectivity in the hetero-Diels-Alder reactions of heterobutadienes, nitrosoalkenes, and heterodienophiles has been extensively reviewed.188 The azadiene l-(f-butyldimethylsilyloxy)-l-azabuta-1,3 -diene (107) reacts with halobenzo-quinones, naphthoquinones, and A-phcnylmalcimidc to yield low to good yields of various pyridine heterocycles (108) (Scheme 38).189 The 4 + 2-cycloaddition of homophthalic anhydride with A-(cinnamylidcnc)tritylaminc produces the 3,4-adduct whereas with A -(cinnamylidcnc)bcnzylidinc the 1,2-adduct is produced.190... 

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. 

K.K. Onchoke et al., Density functional theoretical study of nitrated polycyclic aromatic hydrocarbons. Polycyclic Aromat. Compd. 24, 37-64 (2004)... 

Recently, the borylene complex [p-B(NMe2) (r 5-C5H5)Mn(CO)2 2] (1) was subject to detailed computational studies and the theoretically predicted and the experimentally derived structural parameters were found to be in very good agreement (Table I).117 Density functional theoretical studies have concluded that borylenes BX can be viable ligands in the design of transition metal complexes, which are thermodynamically stable with... 

Amsterdam Density Functional, Theoretical Chemistry, Vrije Uni-versiteit, Amsterdam, The Netherland (1995). 

Tsukamoto T, Ishikawa Y, Vilkas MJ, Natsume T, Dedachi K, Kurita N. Density-functional theoretical study on hydrated DNA duplex Effect of hydrating water molecules on HOMO distribution in DNA. Chem. Phys. Lett. 2006 429 563-569. 

Experimental and theoretical studies have shown that intramolecular nonbonded S- -X (X = O or S) interactions in a large number of organosulfur compounds, including natural antitumor antibiotic leinamycin 5, are important in controlling their structural properties and chemical reactivity <2000JOC4883>. Density functional theoretical and semi-empirical calculations on compound 5 and benzodithiolanone oxide 372 as a member of the model systems 371-374 confirm the stabilizing effect of interactions of that type, which amounts to approximately 6 kcal moF in the case of 5. 

The reference fluid which consists by TPT of non-bonded nitrogen atoms represents the so-called non-associated limit (NAL) of the hard molecular fluid. The nitrogen atoms interact as hard spheres with the diameter ra via the hard sphere pair potential. The density functional theoretical description of the NAL falls back on that which are used by the spherical DFT approach. The latter provides beside other a suitable description for the inhomogeneous hard sphere fluid. 

Giese, B. and McNaughton, D. (2002) Density functional theoretical (DFT) and surface-enhanced Raman spectroscopic study of guanine and its alkylated derivatives 2. Surface-enhanced Raman scattering on silver surfaces. Physical Chemistry Chemical Physics, 4,... 

Zhou Z, Chu S (2009) A time-dependent momentum-space density functional theoretical approach for electron transport dynamics in molecular devices. Europhys Lett 88 17008... 

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