Kinetics of N-oxidation of compounds of the quinoline series and isomeric benzoquinolines by perbenzoic acid in chloroform and aqueous dioxane

The kinetics of the N-oxidation with perbenzoic acid of 15 derivatives of quinoline and benzoquinoline in chloroform and 19 compounds in 50% aqueous dioxane at 20, 25, 30, and 35 °C were subjected to a comparative study. The rate constants, parameters of the Arrhenius equation, and the activation energies for the N-oxidation of the indicated monoazines were determined. A scale of the reactivities of derivatives of the quinoline series and benzoquinolines was calculated within the framework of general perturbation theory.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 89–94, January, 1981.     

An analysis of the vibrational structure of the UV absorption spectrum of acryloyl chloride vapor

The vibrational structure of the UV absorption spectrum of acryloyl chloride vapor was analyzed to obtain detailed information about the torsional vibration levels of the trans and cis isomers in the ground (S ₀) and excited (S ₁) electronic states. The spectrum contained 114 absorption bands of which ～90% were assigned. The 0-0 transition frequencies of the trans and cis acryloyl chloride isomers were determined. Several Deslandres tables for torsional vibrations from the 0–0 transition frequencies and local origins corresponding to the fundamental frequencies of two isomeric molecule forms in both electronic states were constructed. The corresponding systems of torsional vibration levels were determined, and the harmonic frequencies θ_ε and anharmonicity coefficients x ₁₁ of the trans and cis isomers were calculated. The torsional vibration levels in the ground electronic state obtained from the vibrational structure of the UV spectrum are compared with those determined using the Fourier spectrum. The 0–3 torsional transition of the trans isomer was found to be displaced because of Fermi resonance with a fundamental frequency.     

Electronic effects in the reaction of 1,3-diaryl-1,3-diketones with hydrazinopyridines

The regioselectivity of the condensation of electronically unsymmetrical 1,3-diaryl-1,3-diketones with 2-hydrazinopyridine and 2,6-bis-hydrazinopyridine to form N-(2-pyridyl)-3,5-diarylpyrazoles was studied. Significant electronic effects on regioselectivities were observed, and regioselectivities were opposite to those exhibited by perfluoroalkyl/alkyl 1,3-diketones. The electronic effects correlate well to the difference between the Hammett σ⁺ coefficients of the para substituents on the aryl rings.     

Effect of substituent position and lithium,sodium and potassium on the electronic structure of o-, m- and p-methoxybenzoic acids

We have studied the effect of the substituent position in the ring, and lithium, sodium and potassium ions on the electronic structure of o-, m- and p-methoxybenzoic acids (anisic acids) by the use of FT-IR, FT-Raman, Ar matrix FT-IR and ¹H NMR methods, and ab initio calculations at the B3LYP/6-311++G** level of theory. Characteristic shifts of the bands in the spectra and changes in the band intensities along the metal and ligand series were observed. On the basis of the obtained results we may answer the questions: (1) do the substituents in the benzene ring influence the electronic charge distribution in the carboxylic group of anisic acids and alkali metal anisates, (2) do the metal ions affect the electronic charge distribution in the methoxy group, (3) in what way do the alkali metals affect the electronic system of o-, m- and p-anisic acids? The substitution of lithium, sodium and potassium ions in the carboxylic group of o-, m- and p-anisic acids causes changes in the values of bond lengths and angles, and in the electronic charge distribution in the carboxylic group, methoxy group and aromatic ring. The influence of alkali metals on the electronic structure of the ligands is weaker than the effect of methoxy substituents. The effect of Li, Na and K ions on the aromatic ring of the ligands is mostly noticeable in the case of the ortho isomer. The carboxylic and methoxy groups situated in ortho positions in the ring weaken the effect of the alkali metals on the electronic charge distribution in the carboxylic anion and methoxy group.     

π-electron structure,reactivity, and absorption spectra of anthrapyridone

The π-electronic spectra, heats of atomization, and electronic indexes of the lactam and lactim forms of anthrapyridone were calculated by the Pariser-Parr-Pople method with allowance for 25 one-electron configurations. An examination of the π-bond orders and the charges on the atoms showed that a system with a π-electron distribution close to the distribution in anthraquinone and in α-pyridone for the lactam tautometer and in α-hydroxypyridine and anthraquinone for the lactim form is formed in the lactam and lactim of anthrapyridone. The electronic absorption bands were assigned. An analysis of the calculated values demonstrated that the long-wave band in the spectrum of the anthrapyridone is due to charge transfer from the amide group to the ketone group. The reactivity and localization energy indexes of aromatic substitution reactions calculated by the Hückel MO method are in satisfactory agreement with the experimental data.     

Electronic absorption spectra of 2,3- and 2.5-dimethylpyrazines

The electronic absorption spectra of 2,3- and 2,5-dimethylpyrazines were recorded and analysed considering C_2ν and C_2h symmetry for the molecules, respectively. Vibrational analysis of the electronic spectra of these molecules has shown the existence of a vibronic interaction between two electronic states of both the molecules through an out-of-plane bending mode.     

Highly resolved structure of the electronic spectra of azulene in frozen hydrocarbon matrices

Vibronic structures of electronic spectra of azulene embedded into various hydrocarbon matrices are examined at 77°K. High-resolution spectra are obtained using crystalline matrices of isooctane and methylcyclohexane. The O-O bands of third and fourth electronic transitions (33836 and 35550 cm^?1, respectively, in the low-temperature modification of the isooctane matrix) are identified in the absorption spectrum of azulene. Using the P-P-P approximation with the unified parametrization the lowest excited states energies as well as bond lengths for the S_o and their respective changes in the S₁ and S₂ electronic states are calculated. Differences in the vibrational frequencies found for the respective electronic states of the azulene molecule are discussed in connection with the lack of the mirror symmetry between the S₂←S_o absorption and S₂→S_o fluorescence.     

On the origin of the red-shift of the resonant raman profile from the electronic absorption spectrum

The red-shift of the position of the resonant Raman scattering excitation profile with respect to the maximum of the electronic absorption band is explained by considering the variation of the inverse vibronic lifetime _γn in the electronic excited state with quantum number n.     

Electronic configurations of the d- and f-block elements follow the simple rules of energy ordering which were considered to be anomalous,previously

The existing set of principles used for the explanation of electronic configurations, has not been able to explain the electronic configurations of all the d- and f-block elements, systematically. This study proposes a new theory based on two principles, the relative decrease in the energies of the outermost atomic orbitals and the pairing energies of the electrons in different atomic orbitals for the explanation of the electronic configurations of the elements. The theory for the first time has been able to address the anomalies of the electronic configurations of the all the d- and f-block elements, systematically.     

Über thermische,eine Amino-Claisen-Umlagerung einschliessende. Reaktionen von N-Propargyl-naphthylaminen

N-Propargyl-1-naphthylamine ( 1 ), the corresponding N-butinylcompound 5 and N-propargyl-2-naphthylamine ( 2 ) - unlike N-propargyl-anilines - on heating to 250° are converted to a mixture of py-tetrahydro-benzoquinolines and benzoquinolines (scheme 1). The mechanism of these reactions which are induced by a [3s, 3 s] rearrangement of the propargyl group and include a [1,5s] H-shift is depicted in scheme 4. N-Methylation of 1 and 2 reduces for steric reasons the rate of the [1,5s] H-shifts; therefore ring closure of the allenylnaphthylamine intermediates to indols 13 and 14 is favoured (schemes 2 and 5).     

Electronic spectra of tetrahedral CoII complexes with thiourea and its derivatives and with triphenyl-phosphine

The electronic spectra of CoCl₂L₂ (L= triphenylphosphine, thiourea, phenylthiourea and N,N'-diphenylthiourea) have been examined. The parameters Dq and B were calculated and tentative structures of the green and blue forms of the complex dichlorobis(N,N'-diphenylthiourea)cobalt are proposed on the basis of electronic and infrared spectra.     

Synthesis and spectral properties of merocyanine dyes based on fluorene and its derivatives

The di-, tetra- and hexamethine merocyaninyes, the derivatives of fluorene, diphenyl 9H-fluorene-2,7-disulfonate, and bis(2,2,3,3,4,4,5,5-octafluoropentyl) 9H-fluorene-2,7-disulfonate, as well as the derivatives of the heterocycles of moderate (indolylidene and benzotiazolylidene), weak (benzo[c,d]indolylidene and 2,6-diphenylpyrane) and strong (2,6-diphenylpyridine) electron-donor properties were synthesized and their absorption spectra in solvents of different polarity were studied. The quantum-chemical analysis of electronic structure of the synthesized merocyanines was performed and the types of electronic transitions in them were found by the DFT and TDDFT methods with the B3LYP/6-31G(d,p) basis.     

Structural phase transition and 5f-electrons localization of PuSe explored by ab initio calculations

An investigation into the structural phase transformation, electronic and optical properties of PuSe under high pressure was conducted by using the full potential linearized augmented plane wave plus local orbitals (FP-LAPW+lo) method, in the presence and in the absence of spin-orbit coupling (SOC). Our results demonstrate that there exists a structural phase transition from rocksalt (B 1) structure to CsCl-type (B 2) structure at the transition pressure of 36.3 GPa (without SOC) and 51.3 GPa (with SOC). The electronic density of states (DOS) for PuSe show that the f-electrons of Pu are more localized and concentrated in a narrow peak near the Fermi level, which is consistent with the experimental studies. The band structure shows that B 1-PuSe is metallic. A pseudogap appears around the Fermi level of the total density of states of B 1 phase PuSe, which may contribute to its stability. The calculated reflectivity R(ω) shows agreement with the available experimental results. Furthermore, the absorption spectrum, refractive index, extinction coefficient, energy-loss spectrum and dielectric function were calculated. The origin of the spectral peaks was interpreted based on the electronic structures.     

First-principles calculations of the stability and hydrogen storage behavior of C14 Laves phase compound TiCrMn

The structural, elastic properties, electronic structure and hydrogen storage behavior of TiCrMn with a hexagonal C14 structure were investigated by the first-principles calculations within the frame work of DFT. The calculated lattice constants were consistent with the experimental values, and obtained cohesive energy and formation enthalpy showed TiCrMn is of the structural stability. These results also indicated that Mn atoms would optionally substitute on the Cr sites of TiCr₂ phase to form the ternary intermetallic TiCrMn. The five independent elastic constants as well as polycrystalline elastic parameters (bulk modulus B, shear modulus G, Young's modulus E, Poisson's ratio ν and anisotropy value A) were calculated, and then the ductility and elastic anisotropy of TiCrMn were discussed in details. Furthermore, the electronic DOS and charge density distribution of TiCrMn were also calculated, which revealed the underlying mechanism of structural stability and chemical bonding. Finally, the binding energy of hydrogen in hydride TiCrMn(H₃) was investigated, confirming the better hydrogen storage behavior of C14 Laves phase TiCrMn.     

General properties of the electronic structure of alkali metal clusters and Ia-IIa mixed clusters

The results of the systematic ab-initio CI investigation of neutral and charged Li _n , Na _n , BeLi _k and MgNa _k clusters are summarized and analyzed. The general characteristic features of the electronic structure are pointed out:a) The participation of the atomic orbitals, which are empty in Ia and IIa metal atoms, allows for a higher valency of these atoms in clusters.b) Jahn-Teller and pseudo-Jahn-Teller effects strongly influence the electronic and geometric structure of clusters.c) Deformations of cluster geometry can lead to biradicaloid structures with higher spin multiplicity in their ground states.d) The peculiarities of the electronic structures of clusters can be deduced from the presence of many “surface” atoms. The theoretical results agree with experimental data presently available and they are useful for interpretation of the experimental findings.     

Theoretical study on the electronic spectra in cyclic 1,2-diketones

The structural and electronic properties of some α-diketones have been investigated theoretically by performing both Hartree–Fock and density functional theory calculations at HF/6-31G(d,p) and B3LYP/6-31G(d,p) levels of theory.The electronic spectra were calculated by ZINDO and TD methods at each level of theory. The wavelength of the n → π1 electronic transitions was correlated with the torsion angle between the two carbonyl groups in these compounds. The study revealed that the n → π1 electronic transitions in the studied compounds are functions of the torsion angles between the two carbonyl groups within the linkage CO–CO.     

Electronic structure of Lanthanum-carbon clusters

As the attachment of a metal change the molecular and electronic structure of carbon clusters, the electronic properties as ionization potentials (IP) and electron affinities (EA) for small Lanthanum-carbon clusters LaC _n with n=1–6 have been investigated theoretically. They were studied by density-functional-theory (DFT) within LDA and considering Gradient corrections (GC) for the exchange-correlation potential ( Becke-Perdew). The results for both quantities were obtained in good agreement with the experimental data: odd-even alternating IP’s, and no alternations for the EA’s. The different charge location in the carbon chains or at the La atom can explain the different trends of both quantities, respectively.     

Synthesis of terphenyl oligomers as molecular electronic device candidates

Six functionalized bis(phenylene ethynylene)-p,p-terphenyls (BPETs) have been synthesized as potential molecular electronic devices. The molecules containing mono- and dinitro terphenyl cores, were rationally designed based on the electronic properties recently found in oligo(phenylene ethynylene)s (OPEs). From our understanding of the conductance properties in OPEs, improvement of electronic properties may be possible by using BPETs due to a higher rotational barrier between the central aromatic rings of the compounds prepared here. BPETs cores were functionalized with nitro groups and with different metallic adhesion moieties (alligator clips) to provide new compounds for testing in the nanopore and planar testbed structures.     

Ab initio electronic structure of NiCoCrGa half-metallic quaternary Heusler compound

In this study, ab initio calculation results of electronic structure and elastic properties of NiCoCrGa quaternary Heusler compound are presented. Plane wave pseudopotential method is used with spin-polarized Generalized Gradient Approximation (σ-GGA) scheme of the Density Functional Theory (DFT). Static elastic constants of the cubic system satisfy mechanical stability criteria. The cubic phase of the system remains stable under tetragonal distortion. The spin-polarized electronic band structures and density of electronic states indicate a metallic band structure for majority spins, while minority spin structure has semiconducting character. This situation displays a slightly disturbed half-metallic behavior with high-spin polarization ratio (P = 0.961) at Fermi level E_F. Two electronic bands of minority spins resulting from d-states of cobalt atom cross Fermi level at Γ-point. This situation gives a finite but very low density of states at E_F. The material can be classified as a new half-metallic ferromagnet for spintronic applications.