Marginal electron density and density-difference functions

Summary For visual analysis of the density reorganization and distortion, the one-dimensional cut (x, y ₀,z ₀) and the two-dimensional cut (x, y, z ₀) of the three-dimensional electron density difference function (x, y, z) are frequently employed. However, these cut functions do not satisfy any sum rules in contrast to the original difference function (x, y, z). To avoid this difficulty, the use of the marginal electron density functions _x (x) and _xy (x, y) and their difference functions _x (x) and _xy (x, y) is proposed. The marginal densities are condensation of the three-dimensional density onto a particular plane or line of our interest, and they satisfy the sum rule (i.e., the conservation of the number of electrons) exactly. Some basic properties of the marginal electron density are clarified for typical diatomic molecular orbitals. An illustrative application is given for the bonding and antibonding processes in the H₂ system.     

Free energy of transfer of cobalt(III) complexes from water into water—t-butyl alcohol mixtures

The solubility of trans-(Coen₂Cl₂)₂ReCl₆ has been determined in water and in water +t-butyl alcohol mixtures. By comparzng these values with the solubility of Cs₂ReCl₆ in similar mixtures, values for the difference in free energy of transfer, G _t ^o (i) between water and water + t-butyl alcohol can be calculated for i =[Coen₂Cl₂]⁺ and Cs⁺. The introduction of G _t ^o (Cs⁺) then produces values for G _t ^o (Coen₂Cl₂ ⁺). The difference in G _t ^o (i) for i=[Coon₂Cl]²⁺ in the transition state and i=[Coen₂Cl₂]⁺ in the initiad' tate for the solvolysis of the trans-[Coen₂Cl₂]⁺ ion in water + t-butyl alcohol can be derived from the application of a free energy cycle: using G _t ^o (Coen₂Cl₂ ⁺) determined from the solubility measurements allows the calculation of values for G _t ^o (Coen₂Cl²⁺). G _t ^o (i) in water + t-butyl alcohol for bis (1,2-diamino) cobalt (III) ions are compared with G _t ^o (i) for tetrapyridinecobalt (III) ions.     

Raman spectra from partially deuterated water and ice VI to 10.1 kbar at 28°C

High-pressure argon-ion laser-Raman spectra (4880 Å excitation) have been obtained from partially deuterated water and ice VI (20 volume % D₂O) in the OD and OH stretching regions to pressures of 10.1 kbar at 28°C. The Raman spectra from ice VI are the first to be reported at room temperature, and they are similar to the liquid spectra obtained at 9.7 kbar. Raman shifts corresponding to contour intensity maxima were observed to change with pressure rise in the OD and OH stretching regions from v =2513–2490 cm^–1 and v = 3402–3380 cm^–1, respectively, for pressures from 1 bar to 10.1 kbar (ice VI). In addition, a shoulder observed at 1 bar on the OD contour near v = cm^–1 became less distinct and was visually absent for pressures from 6.4 to 10.1 kbar, although a shoulder on the OH contour at about v = cm^–1 intensified gradually for pressures to 9.7 kbar, and abruptly upon freezing at 10.1 kbar. The small effects of pressure on the OD component percentages obtained from computer analysis indicate that hydrogen-bond breakage is not a significant effect of pressure rise, and a downward change in the position of the OD stretching component having the largest Raman shift indicates that the nonhydrogen-bonded OD units or broken O-D...O bonds that exist at 1 bar are probably transformed by close packing due to compression into weak O-D...O bonds that are angularly deformed. In addition, intensification of the OH component at v = cm^–1 upon freezing or upon pressurizing the liquid to 9.7 kbar is indicated by the computer analyses, and an increase in intermolecular coupling is thus favored, as opposed to enhancement of Fermi resonance, because the positions of components at v = cm^–1 and v = cm^–1 are nearly independent of pressure. The computer results also strengthen previous evidence indicating that the OD component which occurs at about v = cm^–1 at 1 bar arises from broken O-D...O bonds, when it is understood that the severely deformed O-D...O bonds of ice VI give rise to intensity at a Raman shift of v = cm^–1, a difference of 37 cm^–1 in the direction of stronger hydrogen-bonding.This paper was presented at the symposium, The Physical Chemistry of Aqueous Systems, held at the University of Pittsburgh, Pittsburgh, Pennsylvania, June 12–14, 1972, in honor of the 70th birthday of Professor H. S. Frank.     

The electronic spectrum of VCr

The electronic spectrum of VCr has been studied using the complete-active-space self-consistent field complete-active-space second-order perturbation theory approach. Potential-energy curves for 12 electronic states have been computed. Transition energies, with respect to the X² ground state, for some of the calculated electronic states are (with possible experimental values within parentheses) 0.53 eV (0.56) for A²⁺, 1.03 eV (1.14) for A⁴, 1.20 eV (1.14) for B², 1.45 eV (1.51) for B⁴, 1.60 eV (1.51, 1.78) for C², and 1.61 eV (1.63) for A^4–. AcknowledgementsThe research reported in this communication was supported by a grant from the Swedish Natural Science Research Council (NFR). S. Alex and D.G. Leopold are acknowledged for providing results from their negative ion photoelectron spectroscopy on VCr.Contribution to Björn Roos Honorary Issue     

Einwirkung von Schwefel und Ammoniak auf Triacetonamin

Zusammenfassung 2,2,6,6-Tetramethylpiperidon-(4) (Triacetonamin), für dessen Herstellung ein verbessertes Verfahren beschrieben wird, reagiert mit Schwefel und NH₃ glatt zum entsprechenden 5,5,7,7-Tetramethylpiperidino-[5,4—c]-³-thiazolin-2-spiro-4-(2,2,6,6-tetramethyl)-piperidin (2).2 reagiert mit CH₃J je nach den angewandten Reaktionsbedingungen wahlweise zum N-mono-,-dioder-permethylierten ³-Thiazolin. Durch Hydrolyse von2 in verd. HCl entsteht fast quantitativ das stabile 3-Mercaptotriacetonaminhydrochlorid; die freie Base kann rasch zu Triacetonamin entschwefelt oder oxydativ in das entsprechende Disulfid übergeführt werden. 3-Mercaptotriacetonamin reagiert mit Ketonen oder Aldehyden in Gegenwart von Ammoniak zu in 2-Stellung unterschiedlich substituierten ³-Thiazolin, von denen die mit Aldehyden erhaltenen Thiazoline zu Thiazolen dehydriert werden können.

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2,2,6,6-Tetramethyl-(4)-piperidone (Triacetonamine), of which an improved method of syntheses is described, reacts with sulfur and ammonia to give the corresponding 5,5,7,7-tetramethylpiperidino[5,4—c]-³-thiazoline-2-spiro-4-(2,2,6,6-tetramethyl)-piperidine (2). The reaction of2 with methyl iodide will give the N-mono-,-di- or-tetramethylated ³-thiazoline in function of the reaction conditions. The hydrolyses of2 in diluted hydrochloric acid will give the stable 3-mercaptotriacetonamine-hydrochloride, the free base of which will rapidly desulfurize to the triacetonamine. Oxidation of the 3-mercapto compound leads to the corresponding disulfide. 3-Mercaptotriacetonamine reacts with ketones or aldehydes in the presence of ammonia to the various in the 2-position different substituted ³-thiazolines.³-Thiazolines thus formed with aldehydes may be dehydrogenated to the corresponding thiazoles.

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Mit 1 Abbildung

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61. Mitt.:F. Asinger, H. Offermanns undC. Dudeck, Mh. Chem.99, 1428 (1968).

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5. Mitt.:F. Asinger, W. Schäfer undH.-W. Becker, Ann. Chem.674, 57 (1964).

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Teil der Dissertation vonE. Michel, Techn. Hochschule Aachen, 1968.     

Effect of intramolecular rotational reorganization of reagents on the ratio between free energies of activation and reaction

Conclusions The relationship between the free energies of activation G and reaction G_o for proton transfer processes have been analyzed, taking into account the effect of hindered rotation of the reagents. We have shown that the considered effect can considerably affect the shape of the G=f(G_o) curve.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 77–81, January 1989.     

Gibbs Energy and Entropy of Mixing in the NaNO2-KNO3 System

The activity and activity coefficients of the components of the NaNO₂-KNO₃ system, determined from the experimental data on the saturated vapor pressure at 798, 823, and 848 K, are used to calculate the relative and excess partial molar Gibbs energies (G _i and G _i ^{e x c}), entropies (S _i and S _i ^{e x c}), and integral relative and excess thermodynamic functions (G, G ^{e x c}, S, and S ^{e x c}) of the system.     

The Influence of Dimerization of Water-Soluble Metalloporphyrins as Photosensitizers on the Efficiency of Generation of Singlet Oxygen

Quantum yields () for the generation of singlet oxygen sensitized by Pd(II) complexes of water-soluble porphyrins: meso-tetrakis(4-N-methylpyridyl)porphine [PdTMPyP]⁴⁺ ( = 0.9), meso-tetrakis(4-N,N,N-trimethylaminophenyl)porphine [PdTTMAPP]⁴⁺ ( = 0.8), meso-tetrakis(4-carboxyphenyl)porphine [PdTCPP]^4– ( = 0.7), and meso-tetrakis(4-sulfonatophenyl)porphine [PdTSPP]^4– ( = 0.5) were determined using a chemical method. It was found that the dimerization and aggregation of metalloporphyrins greatly influence the value. The quantum yields evaluated for the formation of singlet oxygen sensitized by metalloporphyrin monomeric and dimeric forms are _{, M} 0.9 and _{, D} 0.2, respectively, and do not depend on the porphyrin nature.     

Unusual transformation of 3-carbomethoxy-Δ2-pyrazoline under the influence of lead tetraacetate

3-Carbomethoxy-1-(1-carbomethoxy-1-cyclopropyl)pyrazole and 3-carbomethoxy-1-(3-carbomethoxy-1-pyrazolyl)-²-pyrazoline were obtained by the action of lead tetraacetate on 3-carbomethoxy-²-pyrazoline.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1239–1242, September, 1976.     

The effect of the relative location of the double bond and the alkoxy group on the mass-spectrometric behavior of alkoxydihydropyranes

Conclusions The mass spectra ofthree 6-alkoxy-³-dihydropyranes and of three 6-alkoxy-²-dihydropyranes have been studied. As distinct from the previously studied 2-alkoxy-³-dihydropyranes, the dominant fragmentation pattern for the compounds under investigation is by retrodiene degradation. Furthermore, in the case of the ²-isomers the charge is preferentially localized on the olefin fragment while for the ³-isomers, it is located on the diene fragment.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1442–1444, June, 1970.     

Optical and electrical measurements on CO2 covered copper films

Thin polycrystalline copper films are deposited in a special UHV cell on glass substrates and are covered step by step with CO₂. The optical and electrical properties of the films are studied in-situ by means of ellipsometry and resistivity measurements. The properties of the clean films correspond to literature data. In the case of monolayer adsorption of CO₂, the changes in the ellipsometrical angles are +1° and +0.1°, similar to the Cu/O and Cu/CO systems. Three-dimensional island growth leads to a drastical increase of and by several orders of magnitude. The resistivity first quickly decreases and then slowly reapproaches the initial value. This marked kinetics is quantitatively interpreted on the basis of a diffusion model.     

Thermodynamics of the extraction of europium(III) radiotracer by benzyl-phosphonic acid monoester

The extraction of Eu³⁺ from perchloric acid by ethyl hydrogen benzyl phosphonate (HEBP) dissolved in a series of organic diluents, has been studied at different temperatures. From the variation of the distribution ratio with temperature, the thermodynamic functions H, S and G have been determined. The meaning of the experimentally obtained thermodynamic quantities is discussed.     

Steroid derivatives of indolylacrylonitrile

2-Cyano-3-(3-indolyl)-²-steroids are formed when 2-cyano-3-ketosteroids are refluxed with indole and its homologs in acetic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No, 2, pp. 222–223, February, 1973.     

Oxidation of [Co(en)2(SOCH2CO2)]+ by S2O82− and by IO4− in binary aqueous solvent mixtures at pressures up to 1.25 kbar

Second order rate constants and activation parameters H, S, and V have been measured for the oxidation of [Co(en)2(SOCH2CO2)]+ by S2O82– and by IO4– in highly aqueous H2O – t-BuOH mixtures. The changes in solvation on going from the initial to the transition state are discussed on the basis of the transfer functions Gto, Hto and Sto. Whereas Gt changes smoothly as the proportion of t-BuOH increases, the plots of Ht and TSt exhibit mirror behaviour and pass through extrema located around x2(t- BuOH)=0.038. Information on the role of solvation is complemented by the determination of activation volumes. These are discussed in terms of intrinsic and solvational contributions. It is proposed that changes in hydrophobic hydration are of principal importance in determining the response of H, S, and V to changes in solvent composition in H2O – t-BuOH mixtures.     

Structure of korseveridine

Summary The configuration 3, 15-dihydroxy-5, 9, 13, 12, 17, 22-⁸⁽¹⁴⁾-cevine has been proposed for korseveridine.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 2, pp. 101–106, 1968     

Isomerization of 5, 5-dimethylpyrazolines. preparation and properties of 5, 5-dimethyl-Δ1-pyrazoline and 3, 4-dimethyl-Δ2-pyrazoline

Slow distillation of 5, 5, -dimethyl-²-pyrazoline isomerizes it to 5, 5-dimethyl-¹-pyrazoline, and heating the latter with hydrazine hydrochloride reconverts it to the ² isomer. This is the first experimental evidence that the ² double bond in a pyrazoline can move to the ¹ position, i. e., in a direction the reverse of that previously known. The 5, 5-dimethyl-¹ -pyrazoline described is the simplest ¹ pyrazoline hitherto isolated.The authors heartily thank A. A. Petrov for making it possible to chart the PMR spectra, and V. B. Lebedev and V. S. Stopskom for obtaining and treating the spectrograms.     

Additive prediction of thermodynamic functions of hydrofluorides

Summary The experimental data available on the thermodynamic functions ⁰ forMF·nHF hydrofluorides [M=Li, Na, K, Rb, Cs, NH₄, Ag(I) and Tl(I);n=1–3] have been evaluated additively. The unknown values of ⁰ forn=0÷7 are predicted.

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Additive Voraussagen der thermodynamischen Funktionen von Hydrogenfluoriden (Kurze Mitt.)

Zusammenfassung Die vorhandenen experimentellen Daten über die thermodynamischen Funktionen ⁰ von HydrogenfluoridenMF·nHF [M=Li, Na, K, Rb, Cs, NH₄, Ag(I) und Tl(I);n=1–3] werden linear ausgeglichen und die fehlendenden Werte für ⁰ mitn=0÷7 vorausgesagt.

     

Einwirkung von Schwefel und Ammoniak auf Methyl-neopentylketon

Zusammenfassung Bei der Einwirkung von Schwefel und Ammoniak auf Methylneopentylketon in Pyridin bei Raumtemp. bilden sich die beiden theoretisch möglichen Thiazoline-³, das 2,4-Dimethyl-2-neopentyl-5-tert. butyl-thiazolin-³ und das 2-Methyl-2,4-di-neopentyl-thiazolin-³ (etwa im Verhältnis 793). Daneben entsteht 2-Methyl-2,4-dineopentyl-imidazolin-³. Die Darstellung und Charakterisierung der sich vom Methylneopentylketon ableitenden reinen isomeren -Brom- bzw. -Mercaptoketone sowie einiger daraus synthetisierter Thiazoline-³ bzw. Thiazole wird beschrieben.Für Korrespondenz ist diese Adresse zu verwenden.49. Mitt.:F. Asinger, W. Schäfer undA. Saus, Mh. Chem.96, 1278 (1965).Teil der DissertationF. Gentz, Techn. Univ. Dresden 1963.     

Transformed steroids. 149. Microbiological dehydrogenation of Δ5-3β-acetoxysteroids with additional 16-oxa-ring E by means ofCorynebacterium mediolanum

Conclusions Corresponding ⁴-3-ketones were obtained by microbiological dehydrogenation of ⁵-3-acetoxysteroids with an oxa-ring E by means ofCorynebacterium mediolanum culture.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 446–449, February, 1986.     

Reaction of methylmagnesium iodide with steroid keto oxides

Summary The reaction of the 3-acetate of the 20-ketal of 16,17-oxido-⁵-pregnenol-3-one-20 with methylmagnesium iodide and subsequent hydrolysis of the reaction product yielded 16-methyl-⁵-pregnenediol-3 –17-one –20. 18-Nor-17-methyl-17-iso-^5.11-pregnadienediol-3,16-one-20 was formed as a by-product.