Adsorption of<Emphasis Type="Italic"> N</Emphasis>-dodecyl-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethyl-3-ammonio-1-propanesulfonate (DDAPS), a model zwitterionic surfactant,on the Au(111) electrode surface

Electrochemical measurements including cyclic voltammetry, differential capacity, and chronocoulometry have been used to characterize the adsorption behaviors of the zwitterionic surfactant N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (DDAPS) on the Au(111) electrode surface. The thermodynamics of the ideally polarized electrode have been employed to determine the Gibbs excess and the Gibbs energy of adsorption. The results show that the adsorption of DDAPS has a multistate character. The first two states are observed at potentials close to zero charge. At low bulk DDAPS concentrations, it corresponds to the formation of a film of nearly flat adsorbed molecules. At higher concentrations it is converted into a hemimicellar state. The second state is formed at negative potentials and charge densities close to 0 C cm^–2. It corresponds to a film of tilted molecules oriented with the hydrocarbon tail towards the metal and the polar head toward the solution.Dedicated to Professor Zbigniew Galus on the occasion of his 70^th birthday and in recognition of his many contributions to electrochemistry.     

A statistical treatment of large configuration interaction eigenvectors

Summary A statistical treatment for very large configuration interaction (CI) calculations is presented. The energy is written as a sum of elementary contributions, one per determinant, and the statistical choice is made among these elementary contributions. Two types of practical tests determine what conditions must be verified to get reliable results. It is verified that, ifN is the dimension of the CI problem, the size of the statistical samples must grow as to keep the same accuracy in the results.     

Stability Constants of Manganese(II) Alkylenediaminetetraacetates

Stability constants of the manganese(II) complexes with 2-hydroxypropylene-1,3-diamine-N,N,N,N-tetraethanoic and ethylenediamine-N,N,N,N-tetraethanoic acids were determined by the potentiometric method at 298.15 K and ionic strengths of 0.1, 0.5 and 1.0 (KNO₃). The data obtained were extrapolated to the zero ionic strength of the solution using the equation with one individual parameter.     

ESR and ENDOR Investigations on Various <Emphasis Type="Italic">Wurster</Emphasis>’s Radical Cations in Solution. Experimental Results,Theoretical <Emphasis Type="Italic">Ab Initio</Emphasis>, and DFT Calculations

Summary. ESR and ENDOR spectra are reported of several symmetrical substituted N,N,N,N-tetraalkyl-p-phenylenediamine radical cations in solution. Different N,N-alkyl substituted para-phenylenediamines, like the ethyl, n-propyl, and iso-propyl derivative are compared with the parent N,N,N,N-tetramethyl-p-phenylenediamine (Wursters Blue Cation). N,N,N,N-Tetrabenzyl-p-phenylenediamine, 1,4-dipyrrolidinylbenzene, and N,N-bis[4-(dimethylamino)phenyl]piperazine are additionally investigated. Experimental and calculated hyperfine coupling constants are compared. Characteristic UV-VIS data and redox potentials in acetonitrile are reported, together with the syntheses of the compounds.     

Probability of fluctuations of the number of nearest neighbors in a hard sphere liquid: Asymptotic decomposition

Fluctuations of the number of nearest neighbors M _λ inside the coordination sphere of a given radius λ, in a hard sphere liquid (M _λ is the total number of neighbors for all N particles of the system) are analyzed. For the probability density distribution of this random value, an exact asymptotic decomposition over the number of particles N in the system has been derived, and the decomposition coefficients were recorded in terms of the semi-invariants of the random value of Mλ The result coincides completely with the asymptotic decomposition in the central limiting theorem of the probability theory. Due to this, the number of nearest neighbors in a liquid of N hard spheres can be represented as the sum of N independent random values with equal distributions. The hard sphere liquid of N particles was simulated by the Monte Carlo method in the canonical Gibbs ensemble over a wide range of densities (N= 864, periodic boundary conditions, occupancy pg from 0.005 to 0.500). The theoretical equations are in good agreement with the results of simulation.     

Are reaction rate coefficients additive? Revised transition state theory calculations for OH + alkane reactions

Recent shock tube measurements [1,2] of the reactions of OH radicals with various hydrocarbons provide the incentive for revising an earlier model [3] used to carry out thermochemical transition state theory calculations for the reaction rate coefficients of OH radicals with alkanes. In this article, details of the revised model are presented and calculations are described and compared with experiments. Of particular interest is the question of the reliability of an additive formulation for H atom abstraction rate coefficients; i.e., can we evaluate the total rate coefficient as the sum of site-specific rate coefficients, k_total = Σ_ink_i, where we sum either over primary, secondary, and tertiary H atoms or over some larger number of classes of atoms? It is argued that there are two major reasons for expecting different primary, secondary, or tertiary H atoms to have different rate parameters: (1) activation energies may depend on next-nearest neighbors and (2) activation entropies can be mass-dependent. In principle the first factor invalidates the common procedure of treating the total rate coefficient for OH + RH H abstraction processes as the sum of invariant primary, secondary, and tertiary rates multiplied by the respective number of such H atoms in the molecule. The second factor places limits on the accuracy of any additive formulation. A separate question is whether there is sufficient experimental evidence to justify these distinctions, or whether, given experimental and theoretical uncertainties, it is adequate to treat them all as equivalent. It is concluded that (1) mass-dependent variations are just barely discernible; and (2) there are measurable differences among various primary H atom abstractions, and possibly among secondary atoms, but the data base does not justify distinguishing among tertiary H atoms.     

Study of correlation holes. I. Number–sum rules and infinite system

The correlation holes in a finite system of any size are known to satisfy integral number–sum rules directly related to the N-representability of the reduced density matrices. In regard to infinite systems, the same rules are known to be satisfied in the electron gas. It is shown that the number–sum rules are not generally satisfied in any infinite system, and that this happens independently of the kind of boundary conditions assumed in the N → ∞ limit. A violation is explicitly found within the alternant molecular orbital formalism. The apparent paradox is explained in terms of surface effects (end effects in a linear system), which are present in a large, but finite system. In other words the N-representability does not imply the number–sum rules. In the N → ∞ limit the rules are satisfied only in physical systems having short-range correlation.     

Struktur zweier trans-Bis (N,N-dimethylethylendiamin)kobalt(III)-Komplexe. Simulation der sterischen Ligand-Ligand-Wechselwirkungen durch ein ‘Molecular-Mechanics’-Modell

The Crystal and Molecular Structures of Two trans -Bis(N,N-dimethylethylenediamine)cobalt(III) Complexes. Estimate of Steric Ligand-Ligand Interactions by a Molecular-Mechanics Model Two trans-bis (N,N-dimethylethylenediamine)cobalt(III)m complexes with different axial ligands (SNC^?, NO) have been synthesized starting from the corresponding Co^II-amine species. An X-ray crystal-structure analysis revealed widely differing Co? N bond distances. While for the primary amino groups, as in complexes of unsubstituted bidentate amines, bond distances are close to 196 pm, those for the tertiary amino groups are stretched by ca. 10 pm. The good agreement between the molecular geometry as calculated by a molecular-mechanics model and experimental data suggests that the differences in bond distances must be primarily due to simple steric effects.     

Charge calculations in molecular mechanics. Part 8 Partial atomic charges from classical calculations

Summary The CHARGE2 programme, which involves the classical calculation of both the inductive and resonance contributions to the partial atomic charges in molecules is described, and the charges and electrostatic potentials obtained presented for some illustrative examples.In substituted methanes (CH₃X, CF₃X, CCl₃X) the effects of varying the electronegativity of the substituents and the - and -substituent contributions are clearly illustrated for a variety of substituent groups X.The problems involved in the inclusion of silicon into this scheme are detailed, together with the methods of overcoming them. The partial atomic charges ( and contributions) and electrostatic potentials for some silicon oxygen compounds are presented and discussed.The partial atomic charges from CHARGE2 for all the natural amino acids as their N-acetyl, N-methyl-amides are given and compared with those obtained from the AMBER and ECEPP/2 force fields. Considerable differences in these figures are observed, with the AMBER charges consistently much larger than those from the other two methods.The CHARGE2 partial atomic charges and electrostatic potentials for the four common nucleic acids, adenine, cytosine, guanine and thymine, are given and compared with those derived from other calculations. Again there is general similarity but also there are considerable differences, with those from the AMBER force field somewhat larger than the other methods.For previous parts in this series, see Refs. 1-7.     

Die thermische Zersetzung von Bariumazid-Einkristallen, 8. Mitt.: Theorie des Zerfalls der N3 o-Radikale und der Bildung von Ba3N2

Zusammenfassung Die beim thermischen Zerfall von Alkali- und Schwermetallaziden auftretende und bei den Erdalkaliaziden fast völlig fehlende UV-Strahlung wird dem ÜbergangA ³ _u ⁺ X ¹ _g ⁺ im N₂-Molekül unter Berücksichtigung versciedener Schwingungszustände (v, v) zugeordnet. Monomolekularer Zerfall der N ₃ ^o -Radikale ist impuls-und spinverboten. Bimolekularer Zerfall der an der Zerfallsgrenzfläche schwach getrappten N ₃ ^o -Radikale verläuft in Form einer zweidimensionalen quasi-Gasreaktion und kann adiabatisch über lineare oder cyclische Übergangskomplexe zu N₂ in¹ _g ⁺ und³ _u ⁺ -Zuständen führen, wenn nur die Korrelation der Elektronenterme betrachtet wird. Korrelation über Elektronen-Schwingungsterme erlaubt daneben auch die Entstehung desB ³II_g-Termes und erklärt weiters das Auftreten der SpeziesA ³ _u ⁺ in angeregten Schwingungszuständen. Desaktivierung dieses metastabilen Zustandes erfolgt bei der Zersetzung von Ba(N₃)₂ durch Reaktion mit Ba₂ an der Zerfallsgrenzfläche unter Ausbildung der instabilen Zwischenverbindung Ba₂N₂ bzw. [Ba₄N₄], welche zu Ba+Ba₃N₂ im experimentell gefundenen Verhältnis weiter zerfällt.

---

The UV-radiation accompanying thermal decomposition of alkali-and heavy metal azides but being very weak in the case of alkaline-earth azides is attributed to vibronic transitions between the electronic statesA ³ _u ⁺ andX ¹ _g ⁺ of N₂. Unimolecular decomposition of the N ₃ ^o -radicals is forbidden by the conservation rules for angular momentum and spin. Bimolecular decomposition of two N ₃ ^o -radicals trapped weakly at the decomposition interface can be supposed to proceed like a two-dimensional gasreaction via either linear or cyclic transition complexes. Correlation of the electronic states of reactants and products can yield both¹ _g ⁺ and³ _u ⁺ -states of N₂, whereas by correlation of the vibronic states theB ³II_g-state of N₂ too can be obtained. Vibronic correlation explains the vibrational excitation of the³ _u ⁺ -state leading to the observed bands in the UV-region. In the case of Ba(N₃)₂-decomposition deactivation of the metastable state³ _u ⁺ takes place by reaction with Ba₂ at the interface yielding an instable intermediate compound Ba₂N₂ and [Ba₄N₄], resp., which finally decomposes into Ba and Ba₃N₂ in the ratio found experimentally.

---

---

Mit 4 Abbildungen

---

7. Mitt.,K. Torkar undH. T. Spath, Mh. Chem.99, 118 (1968).     

Novel azaandrostane derivatives for the synthesis of 17β‐(N‐tert‐butyl carbamoyl)‐4‐aza‐5α‐androst‐1‐ene‐3‐one

A new industrially viable process for the preparation of 1β‐(N‐tert‐butyl carbamoyl)‐4‐aza‐5α‐androst‐1‐ene‐3‐one, also known by the generic name finasteride ( 6 ) from the new azaandrostane derivatives such as 1β‐(N‐tert‐butyl carbamoyl)‐4‐benzoyl‐4‐aza‐5α‐androstane‐3‐one ( 4 ), 1β‐(N‐tert‐butyl carbamoyl)‐4‐benzoyl‐4‐aza‐5α‐androst‐1‐ene‐3‐one ( 5 ) is reported. In this process, benzoyl group is demonstrated as a novel protecting group for lactamic NH group. The structures of newly prepared compounds were established on the basis of spectral data (IR, ¹H‐NMR, and MS).     

Intersequence cyclization in copolymers of N-vinyl carbamates

Monomer reactivity ratios determined for the copolymerization of tert-butyl N-vinylcarbamate (r_A = 0.55 ± 0.05) with phenyl N-vinylcarbamate (r_B = 2.08 ± 0.15) indicate that the monomer units are distributed randomly along the polymer chains. The following sequence of reactions was used to cause intersequence cyclization between tert-butyl N-vinylcarbamate and phenyl N-vinylcarbamate units in the copolymers. The extent of cyclization obtained was in accord with that expected for random copolymers.      

On the molecular electrostatic potentials obtained with CNDO and INDO wave functions

Molecular electrostatic potentials computed with CNDO/2 and INDO wave functions are shown to present systematic differences with respect to ab initio potentials in the case of out-of-plane potentials and in-plane vicinal hetero atoms in planar hetero molecules.     

Bohr Sommerfeld quantisation and molecular potentials

We combine, within the Bohr Sommerfeld quantization rule, a systematic perturbation with asymptotic analysis of the action integral for potentials which support a finite number of bound states with E < 0 to obtain an interpolation formula for the energy eigenvalues. We find interpolation formulae for the Morse potential as well as potentials of the form \({V=V_0 \left[ {\left( {\frac{a}{x}} \right)^{2k}-\left( {\frac{a}{x}}\right)^{k}} \right]}\). For k = 6 i.e. the well known Lennard Jones potential this yields results within 1 per cent of the highly accurate numerical values. For the Morse potential this procedure yields the exact answer. We find that the result for the Morse potential which approaches zero exponentially is the \({k\rightarrow\infty}\) limit of the Lennard Jones class of potentials.     

Salt effect in the base-catalyzed polymerization of unsaturated amide compounds. IV. Polymerization of p-vinylbenzamide in the presence of LiCl/N,N,N′,N′-tetramethylethylenediamine

In the presence of lithium chloride and N,N,N′,N′-tetramethylethylenediamine, p-vinylbenzamide was polymerized in basic media to form a polymer with structure consisting of units due to both proton transfer and vinyl type polymerization, whereas in the presence of the salt alone the monomer underwent exclusively vinyl type of polymerization to give a polystyrene derivative:      

Thermal reactions of N‐alkyl‐2‐benzylaniline and N‐alkyl‐N′‐phenyl‐o‐phenylenediamine: An unusual route to 2‐phenylindole and 2‐phenylbenzimidazole

Thermal cyclization reactions of N‐alkyl‐2‐benzylaniline 1a‐d and N‐alkyl‐N′‐phenyl‐o‐phenylenediamine 2a‐b were carried out expecting to get seven‐membered heterocyclic compounds. However, the results show that aside from the formation of the normally expected six‐membered ring products of acridine 5 , anthracene 6 , and phenazine 8 , thermal cyclization of N‐alkyl‐2‐benzylaniline and N‐alkyl‐N′‐phenyl‐o‐phenylenediamine also resulted to the unexpected formation of 2‐phenylindole 3 and 2,3‐diphenylindole 4 , and 2‐phenylbenzimidazole 7 , respectively.     

Facile regiospecific syntheses of N‐α,N‐1(τ)‐dialkyl‐l‐histidines

Two diverse methodologies describe the first synthesis of suitably protected N‐α,N‐1(τ)‐dialkyl‐Lhistidine derivatives. Synthesis of suitably protected N‐α,N‐1(τ)‐dialkyl‐L‐histidines 7‐9 containing different alkyl groups at the N‐α and N‐1(τ) positions was achieved in four steps starting from L‐histidine methyl ester. Whereas, in the one‐step alternate route N‐α‐Boc‐L‐histidine methyl ester upon direct and simultaneous N‐α and N‐1(τ) alkylation with various alkyl halides in the presence of sodium hydride in DMF easily afforded N‐α,N‐1(τ)‐dialkyl‐L‐histidines 14 containing identical alkyl group at the N‐α and N‐1(τ) positions in high yields. Both procedures allowed facile entry to methyl and other higher alkyl groups at the N‐α‐position of the histidine ring     

Perturbation theory for excited states of molecules. I

The problem of perturbations of excited states is discussed and three methods are developed. The first of these uses a zero order wave-function made up of a linear sum of singly excited SCF configurations, whereas the second uses just one of these configurations. The third method is restricted to small -systems, the zero order wave-function being a linear sum of all possible determinants formed from the basis set used. The perturbations considered here are one-electron operators. Example calculations are performed on the butadiene molecule within the context of the -electron approximation.

---

Zusammenfassung Für das Problem einer Störung von Einelektronen-Operatoren für angeregte Zustände werden drei Verfahren vorgeschlagen: Erstens die Verwendung einer Zustandsfunktion nullter Ordnung, die eine Linearkombination einfach angeregter SCF-Konfigurationen ist, zweitens die entsprechende Verwendung nur einer ausgewählten Konfiguration. Drittens läßt sich, wenn auch nur bei kleinen -Elektronensystemen, als nullte Näherung eine Linearkombination von allen möglichen angeregten Konfigurationen verwenden. Als Beispiel wird das -Elektronensystem des Butadiens gewählt.

---

Résumé Discussion du problème de perturbation pour les états excités et développement de trois méthodes. La première utilise une fonction d'ordre zéro combinaison linéaire de configurations SCF monoexcitées, alors que la seconde utilise seulement une de ces configurations. La troisième méthode est restreinte à de petits systèmes , la fonction d'onde d'ordre zéro étant une combinaison linéaire de tous les déterminants construits dans la base utilisée. Les perturbations envisagées ici sont constituées par des opérateurs monoélectroniques. La molécule de butadiène sert d'exemple dans le cadre de l'approximation à électrons .

     

Heteroaryl‐substuted semicarbazones: Synthesis and anticonvulsant activity of N‐(3‐methylpyridin‐2‐yl)‐substituted semicarbazones

A series of substituted N‐(3‐methylpyridin‐2‐yl) semicarbazones was designed and synthesized to meet the structural requirements essential for anticonvulsant activity. The structures of all the synthesized compounds were confirmed by means of spectral and elemental analysis. All the compounds were evaluated for their anticonvulsant activity by maximal electroshock seizures (MES) test, subcutaneous pentylenetetrazole (scPTZ) screen, subcutaneous strychnine (scSTY) pattern test and subcutaneous picrotoxin (scPIC) seizure threshold test along with the behavioral, and neurotoxicity evaluation. A number of N‐(3‐methylpyridin‐2‐yl) semicarbazone derivatives exhibited significant protection after intraperitoneal administration at the dose of 100 and 300 mg/kg. Compound N¹‐(3‐methylpyridin‐2‐yl)‐N⁴‐(isatin) semicarbazone ( 19 ) emerged as the most active analogue of the series, being more effective in most of the test models than ethosuximide and sodium valporate.