MO-SCF calculations for B2O3

The results of ab-initio molecular self-consistent field calculations with atomic optimized Gaussian bases are reported for the B₂O₃ molecule. These distinguish between several plausible structures and yield a V-shaped structure as the minimum energy geometry.This work was supported by the National Science Foundation program of Research Participation for College Teachers, Grant No. GY-5404, and by the Air Force Office of Scientific Research, Grant No. AFOSR-68-1438.     

Atom-surface elastic scattering in the presence of laser radiation

A qualitative discussion on atom-surface elastic scattering taking place in the presence of laser radiation is given. It is suggested that appreciable effects of laser radiation on diffraction patterns may be expected if the laser radiation is capable of inducing electronic transitions in atoms with a large probability.Research sponsored by the Air Force Office of Scientific Research (AFSC), United States Air Force, under Contract No. F49620-78-C-0005, and the National Science Foundation under Grant No. CHE77-27826. The United States Government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright notation hereon.Alfred P. Sloan Research Fellow, 1976–1980; Camille and Henry Dreyfus Teacher-Scholar, 1975–1980.     

Relaxation of laser induced transient plasmas in liquids

Transient plasma is induced in H₂O, D₂O, CS₂, optical glass, and Plexiglas by single pulses of aQ-switched neodymium laser in the power density range of 0.4 to 0.9 GW cm^–2. The relaxation times for the simple exponential decay of intensity of a white continuum emitted by all samples have been determined. Possible mechanisms of the formation and decay of the plasmas are discussed.With 2 FiguresThe experimental part of this work was performed at the University of Utah and was supported in part by the Directorate of Chemical Sciences, Air Force Office of Scientific Research under Grant AFOSR-69-1717-D.     

Recursive intermediate factorization and complete computational linearization of the coupled-cluster single,double, triple,and quadruple excitation equations

Summary The nonlinear CCSDTQ equations are written in a fully linearized form, via the introduction of computationally convenient intermediates. An efficient formulation of the coupled cluster method is proposed. Due to a recursive method for the calculation of intermediates, all computational steps involve the multiplication of an intermediate with aT vertex. This property makes it possible to express the CC equations exclusively in terms of matrix products which can be directly transformed into a highly vectorized program.This work has been supported by the U.S. Air Force Office of Scientific Research, Grant No. 90-0079     

Ground states of molecules

Detailed MINDO/2 calculations of naphthalene using the SIMPLEX minimization algorithm are reported. Comparison of results with experiment and various approximations is made.The results are in good agreement with experiment.Part XXII: Bingham,R.C., Dewar, M.J.S.: J. Amer. chem. Soc. (in press).This work was supported by the Air Force Office of Scientific Research through Contract F44620-70-C-0121, and the Robert A. Welch Foundation through Grant F-126.     

Table of Sanibel (spin projection) coefficients

Projection coefficients for total spin angular momentum of systems of 1 to 20 particles with spin 1/2 have been calculated on a digital computer.

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Zusammenfassung Die Projektionskoeffizienten für Eigenzustände des Betrages des Spindrehimpulses sind für Systeme von 1 bis 20 Spin-1/2-Teilchen berechnet worden.

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Résumé Les coefficients de projection du moment angulaire de spin total de systèmes de 1 à 20 particules de spin 1/2 ont été calculés sur un ordinateur.

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The research reported in this paper was sponsored in part by the Gustaf VI Adolf's 70-Years Fund for Swedish Culture, Knut and Alice Wallenberg's Foundation, and in part by the Aerospace Research Laboratories, (OAR), through the European Office of Aerospace Research, United States Air Force, under Contract AF 61(052)-701.     

Theoretical studies of atmospheric molecules: SCF and correlated energy levels for the NO2, NO 2 + and NO 2 − systems

SCF and MC-SCF/CI calculations were carried out on the low-lying electronic states of NO₂, NO ₂ ⁺ and NO ₂ ^– , using a double-zeta quality basis set of contracted Gaussian functions. The calculations were performed primarily at the equilibrium geometry (R _NO = 2.25 a_o, _ONO=134 °) of theX ² A ₁ state of NO₂. SCF calculations on NO ₂ ⁺ in a linear conformation were also performed. Results are presented and compared with experiment and other calculations.Research supported in part by Air Force Delivery Orders F33615-72-M-5015 and MIPR889474-00117 and Air Force Office of Scientific Research and in part by the United States Energy Research and Development Administration.     

Statistical theory for hydrogen bonding fluid system of AaDd type (Ⅱ): Properties of hydrogen bonding networks

Making use of the invariant property of the equilibrium size distribution of the hydrogen bonding clusters formed in hydrogen bonding system of A_aD_d type, the analytical expressions of the free energy in pregel and postgel regimes are obtained. Then the gel free energy and the scaling behavior of the number of hydrogen bonds in gel phase near the critical point are investigated to give the corresponding scaling exponents and scaling law. Meanwhile, some properties of intermolecular and intramolecular hydrogen bonds in the system, sol and gel phases are discussed. As a result, the explicit relationship between the number of intramolecular hydrogen bonds and hydrogen bonding degree is obtained. Supported by the National Natural Science Foundation of China (Grant Nos. 20303006 and 20574016), the Natural Science Foundation of Hebei Province (Grant Nos. B2006000959 and B2004000093) and the Natural Science Foundation of Education Committee of Hebei Province (Grant No. 2003101)     

An efficient copper(II)-catalyzed synthesis of benzothiazoles through intramolecular coupling-cyclization of N-(2-chlorophenyl)benzothioamides

A wide range of 2-aryl or 2-alkyl-substituted benzothiazoles are synthesized through intramolecular C_(aryl)-S bond forming-cyclization using copper(II)-BINAM-catalyzed coupling of less reactive N-(2-chlorophenyl)benzo or alkylthioamide under mild reaction conditions (82 °C).     

Degradation of an Acetylene Terminated Sulfone (ATS) resin

A study of the rates and mechanisms of degradation of an acetylene terminated sulfone resin, more precisely, bis[4-(3-ethynyl phenoxy) phenyl] sulfone and its higher oligomers, under high vacuum conditions, and under a flowing atmosphere of nitrogen, was made using techniques such as programmed thermogravimetry (TG), Thermal Volatilization Analysis (TVA), and Sub Ambient Thermal Volatilization Analysis (SATVA). Gravimetric product analyses made in conjunction with quantitative Infrared and Nuclear Magnetic Resonance Spectroscopy were used to develop a quantitative product distribution for the process. By so doing, we established the sulfone residue as the thermal weak link in the system, and identified two overlapping processes of backbone polyphenylether thermal decomposition; a low temperature process involving scissions promoted by the sulfone moiety, and a higher temperature process involving more random scissions of residual sulfone free polyphenylethers.

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Zusammenfassung Mittels TG, TVA und SATVA wurde eine Untersuchung der Reaktionsgeschwindigkeit und des Reaktionsmechanismus des Abbaues von Sulfonharz mit endständigem Acetylen (von bis-[4-(3-ethinylphenoxy)phenyl]sulfon und seiner höheren Oligomere) im Hochvakuum bzw. in einer dynamischen Stickstoffatmosphäre durchgeführt. In Verbindung mit quantitativer IR- und NMR-Spektroskopie wurde eine gravimetrische Analyse der Produkte erstellt, um eine quantitative Produktezusammensetzung des Prozesses zu erhalten. Der Sulfonrest konnte somit als schwaches Kettenglied des Systemes erkannt und zwei überlappende Prozesse der thermischen Zersetzung des hauptkettigen Polyphenylethers identifiziert werden: ein Prozess bei niedrigerer Temperatur beinhaltet durch die Sulfonkomponente geförderte Spaltungen und ein zweiter Prozess verursacht bei höherer Temperatur Random-Spaltungen des verbleibenden sulfonfreien Polyphenylethers.

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W.T.K. Stevenson would like to acknowledge the financial assistance of the National Research Council who funded a Research Associateship at Wright Patterson Air Force Base for the duration of this work. In addition, both authors would like to offer thanks to Mr. J. Heines for his sound technical assistance, and to Mr. R. Grant who fabricated most of the glassware described here.     

Two novel interpenetrated zinc(II) and cadmium(II) coordination polymers based on 4-imidazole-benzoate: Syntheses,crystal structures and properties

Two novel interpenetrated coordination polymers, [Zn(IBA)₂] _n (1) and {[Cd(IBA)₂(H₂O)]·4H₂O} _n (2), have been synthesized by using 4-imidazole-benzoic acid (HIBA) as ligand under hydrothermal conditions. Complex 1 crystallizes in a chiral space group and has a two-fold interpenetrated 2D network structure with (4,4) topology, while complex 2 is a 3D porous dia network with four nets interpenetrating each other. The SHG activity of 1 and the photoluminescent property of 2 have been investigated. Supported by the National Natural Science Foundation of China (Grant Nos. 20731004 & 20721002) and the National Basic Research Program of China (Grant No. 2007CB925103)     

Multiphysics modeling of electric-swing adsorption system with in-vessel condensation

Mathematical modeling of an Electric-Swing Adsorption (ESA) system (adsorption cycle with electrothermal desorption step, performed by direct heating of the adsorbent particles by passing electric current through them), with annular, radial-flow, cartridge-type fixed-bed and in-vessel condensation, is performed by using Comsol Multiphysics™ software. Three multiphysics models are built, in order to describe three stages of a compete ESA cycle: adsorption, electrothermal desorption before the start of condensation and electrothermal desorption with in-vessel condensation. In order to describe the complete ESA cycle the models for the three stages are integrated, by using a combination of Comsol Multiphysics™ and Matlab™. The models were successfully used for simulation of separate stages of the process and of the complete ESA cycles, as well as for investigation of the influences of the main operational parameters on the process performance. The views and conclusions contained herein are those of the author and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Air Force Office of Scientific Research or the U.S. Government.     

W(CO)5(L)-catalyzed 6-endo-selective cyclization and formal Cope rearrangement of allenyl silyl enol ethers

On treatment of 5-siloxy-1,2,5-trienes with a catalytic amount of W(CO)₆ under photoirradiation, two types of synthetically useful compounds, that is, 6-endo-cyclized products or formal Cope rearrangement products, are obtained selectively via the same intermediates simply by changing reaction conditions. In these reactions, electrophilic activation of the allene moiety is effectively achieved by coordination of W(CO)₅, allowing intramolecular attack by neutral carbon nucleophiles in a 6-endo manner.     

Studies of surface processes of electrocatalytic reduction of CO<Subscript>2</Subscript> on Pt(210), Pt(310) and Pt(510)

Surface processes of CO2 reduction on Pt(210), Pt(310), and Pt(510) electrodes were studied by cyclic voltammetry. Different surface structures of these platinum single crystal electrodes were obtained by various treatment conditions. The experimental results illustrated that the electrocatalytic activity of Pt single crystal electrodes towards CO2 reduction is decreased in an order of Pt(210)＞Pt(310)＞Pt(510), i.e., with the decrease of (110) step density on well-defined surfaces. When the surfaces were reconstructed due to oxygen adsorption, the catalytic activity of all the three electrodes has been enhanced to a certain extent. Although the activity order remains unchanged, the electrocatalytic activity has been enhanced more significantly as the density of (110) step sites is more intensive on the Pt single crystal surface. It has revealed that the more open the surface structure is, the more active the Pt single crystal electrode will be, and the easier for the electrode to be transformed into a surface structure that exhibits higher activity under external inductions. However, the relatively ordered surfaces of Pt single crystal electrode are comparatively stable under the same external inductions. The present study has gained knowledge on the interaction between CO2 and Pt single crystal electrode surfaces at a microscopic level, and thrown new insight into understanding the surface processes of electrocatalytic reduction of CO2.     

Synthesis of Fréchet-type dendritic homotriptycenes

A rapid and efficient synthesis of novel dendrimer homotriptycenes is presented. The dendronized 9,10-dihydroanthracen-9-ols 4, having high electron densities in the benzene rings of the Fréchet-type dendrons, exhibited in the presence of acid a quantitative transannular ring closure to the corresponding dendritic homotriptycenes. The electron-donating Fréchet-type dendrons enabled the intramolecular FC alkylation by a regioselective 1,7-elimination of H2O.     

6-Membered ring intermediates in polymerization of N-carboxyanhydride-L-α-arginine in H2O

In polymerization of N-carboxyanhydride-L-α-arginine (L-Arg-NCA) in H₂O, nucleophilic reaction of guanidine group with the carbonyl group of L-Arg-NCA leads to quick intramolecular rearrangement, yielding a 6-membered ring intermediate 1-amidino-3-amino-2-piperidone, which is either elongated by another L-Arg-NCA yielding arginyl-1-amidino-3-amino-2-piperidone or hydrolyzed to L-α-arginine. The oligoarginines are formed mainly through hydrolysis of arginyl-1-amidino-3-amino-2-piperidones. This is a unique pathway in polymerization of L-Arg-NCA with regard to the usual pathway of elongations by reaction of N-carboxyanhydride-L-α-amino acid with L-α-amino acid or oligopeptides. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users. Supported by the Special Research Project of Beijing Scientific and Technical Committee (Grant No. Z00063002040191) and the Natural Basic Research Program of China (Grant No. 2007CB935901)     

Bi(OTf)3-Catalyzed Intramolecular Amination of Triazenylaryl Allylic Alcohols: A Stereoselective,High-Yield Synthesis of (E)-3-Alkenyl 2H-indazoles

An efficient Bi(OTf)₃-catalyzed synthesis of 3-alkenyl-2-pyrrolidine-2H-indazoles from triazenylaryl allylic alcohols via the intramolecular direct amination process is reported. Compared with the dodecyl benzenesulfonic acid (DBSA)-catalyzed method, the new method is more efficient and gives greater yields and functionality tolerance. Additionally, the 3-alkenyl-2-pyrrolidine-2H-indazoles can be transformed to a series of new products under different reaction conditions.     

Syntheses, structures and magnetic properties of a family of one-dimensional M(Ⅱ)-lanthanide(Ⅲ) (M =Ni(Ⅱ) and Zn(Ⅱ)) coordination polymers

A series of 1D nickel(Ⅱ)/zinc(Ⅱ)-lanthanide(Ⅲ) coordination polymers, [M(μ-L)2Ln(NO3)3]n· solvents (HL =bis(2-pyridylcarbonyl)amine; M = Ni, Ln = Gd (1 · NiGd), Tb (2· NiTb), Dy (3· NiDy), Ho (4· NiHo), Y (5· NiY);M = Zn, Ln =Gd (6· ZnGd), Tb (7· ZnTb), Dy (8· ZnDy), Ho (9· ZnHo); solvents = H2O or H2O-ethanol), was synthesized and characterized. All of the complexes are isostructural at 293 K and crystallize in the orthorhombic space group Fddd. Magnetic measurements were performed on 1-9, where weak ferromagnetic interaction is found in 1 · NiGd, ferromagnetic interaction in 2·NiTb and 3·NiDy, and antiferromagnetic interaction in 4· NiHo. A remarkable dc magnetic field dependence of ac susceptibilities was found in this series of complexes.     

The study of the dehydration and dehydroxylation of smectites by emanation thermal analysis

The dehydration and dehydroxylation of the smectites, beidellite and montmorillonite (dioctahedral) and saponite and laponite (trioctahedral), were investigated by ETA, DTA, TG and X-ray diffractions. There are differences between the behaviors of di- and trioctahedral clays which are due to the differences in the ability of the exchangeable cations to migrate into hexagonal holes of the SiO₄ network and due to the fact that the dehydroxylation and recrystallization of dehydroxylated trioctahedral smectites occur simultaneously, whereas there is a temperature gap of about 300°C between the dehydroxylation and the recrystallization of dioctahedral smectites.Dedicated to Dr. Robert Mackenzie on the occasion of his 75th birthdayThe authors wish to thank Laporte Industries, Inc. UK for the laponite sample.This research was supported under Project No. C12-219, Grant No. HRN5544 G002069, U.S.-IsraelCooperative Development Research Program, Office of the Science Advisor, U.S. Agency for International Development.     

Iron(0)-Mediated Stereoselective (3+2)-Cycloaddition of Thiochalcones via a Diradical Intermediate

Reactions of α,β-unsaturated aromatic thioketones 1 (thiochalcones) with Fe₃(CO)₁₂ leading to η⁴-1-thia-1,3-diene iron tricarbonyl complexes 2 , [FeFe] hydrogenase mimics 3 , and the thiopyrane adduct 4 are described. Obtained products have been characterized by X-ray crystallography and by computational methods. Completely regio- and diastereoselective formation of the five-membered ring system in products 3 , containing four stereogenic centers, can be explained by an unprecedented, stepwise (3+2)-cycloaddition of two thiochalcone molecules mediated by Fe₃(CO)₁₂. Quantum chemical calculations aimed at elucidation of the reaction mechanism, suggest that the formal (3+2)-cycloaddition proceeds via sequential intramolecular radical transfer events upon homolytic cleavage of one carbon-sulfur bond leading to a diradical intermediate.