Synthesis and chiral-optical properties of (+)-3-methyl-3,4-dihydroisoquinoline-1-thione

(+)-3-Methyl-3,4-dihydroisoquinoline-1-thione was obtained by sulfuration of (+)-3-methyl-3,4-dihydroisoquinolone with phosphorus pentasulfide or by cyclization of (+)--benzylethyl isothiocyante under the influence of polyphosphoric acid. Measurements of the rotatory dispersion and circular dichroism showed the presence of two positive Cotton effects due to n^* and ^* transitions in the thioamide chromophore, as well as Cotton effects apparently due to ^* transitions in the aromatic chromophore.Communication XXXV from the series Stereochemical Investigations. See [11] for communication XXXIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 94–97, January, 1976.     

Some peculiarities of π—π interactions between tetraphenylporphine metal complexes and aromatic solvents

The — complexes of metal tetraphenylporphinates with benzene, toluene, and xylenes were characterized by means of thermogravimetry. The ability of metalloporphyrins to form — complexes with certain -donor molecules depends largely on the -acceptor capacity of the macroheterocycle, and on the peculiarities of the metal—porphyrin coordinative linkage. Stoichiometry, energy parameters, and thermal stability of the - complexes of metalloporphyrins with various aromatic ligands are determined to a great extent by the molecular structure of solvents.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp.850–853, May, 1993.     

Calculation of some electronic excited states of formaldehyde

The optimized MO's of several excited states of formaldehyde have been calculated by means of a large basis set of modified Gaussian functions; particular attention has been paid to the * transition. The total energy of the various states has been obtained as the sum of the SCF and correlation energies; the last one has been calculated as a functional of the electronic density. The calculated values for the transition energies are in good agreement with the experiment. A strong interaction of the * state with the continuum is evidentiated; this fact can justify the absence of the * band in the absorption spectrum.     

PPP and CNDO calculations for protonated molecules

CNDO calculations have been used to obtain the one-centre core integrals for protonated azines required in calculating the ^* absorption spectra of such molecules using the PPP method. Calculated spectra for both the parent and the protonated molecules are obtained in satisfactory agreement with experiment. The changes in the -framework of the molecules on protonation are also discussed in terms of the CNDO results.

---

Zusammenfassung CNDO-Rechnungen wurden benutzt, um die Einzentren-Rumpf-Integrale für protonierte Azine zu erhalten, die bei der Berechnung der ^* -Absorptionsspektren mit Hilfe der PPP-Methode benötigt werden.Die berechneten Spektren für die Ausgangsmoleküle und die protonierten Moleküle sind in zufriedenstellender Übereinstimmung mit dem Experiment. Die Veränderungen im -Rumpf der Moleküle bei der Protonierung werden ebenfalls mit Hilfe der CNDO-Resultate diskutiert.

---

Résumé Des CNDO ont tét utilisés pour obtenir les intégrales de coeur monocentriques des azines protonées nécessaires au calcul de leur spectre d'absorption ^* par la méthode PPP. Les spectres calculés pour les molécules protonées ou non sont en accord satisfaisant avec l'expérience. Les modifications subies lors de la protonation par le squelette sont discutées en fonction des résultats des calculs CNDO.

     

Connection between the electronic structure of tin in its compounds and the isomer shifts in the Mössbauer spectra

A formula is obtained which relates the isomer shifts in the Mössbauer spectra to the electronic structure of tin in its compounds. It is shown that these formulas describe the isomer shifts of various kinds of chemical compounds: tetravalent tin with -bonding (tin tetrahalides), tetravalent tin with no -bonding (compounds in which the tin is bound to alkyl, aryl, or metal carbonyl radicals), divalent tin, etc. The formulas are used to analyze the electronic structures of tin in compounds of these classes. It is shown that in tetravalent tin compounds with -bonding the isomer shift in the negative direction (with respect to -Sn) is due to the decreased number of 5s-valence electrons, and in the absence of -bonding, by an increase in the number of 5s-valence electrons.     

Molar cotton-mouton constants and anisotropy of magnetic susceptibility of benzyl chlorides and benzyl bromides

Conclusions Due to thearom^–gsC-Hal* interaction, the magnetic susceptibility ellipsoids of -haloalkylbenzenes, with the exception of ,'-p-xylylidene bromide, undergo rearrangement of the semimajor axes with a decrease in the diamagnetic component in direction 1, 4 and along the axis of symmetry of the electrons in the ring.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No No. 7, pp. 1552–1557, July, 1986.     

Homodimerization of spiro{bicyclo[2.2.1]Hepta-2,5-Diene-7,1′-cyclopropane}, catalyzed by group VIII transition metal complexes

Conclusions The homodimerization of spiro{bicyclo[2.2.1]hepta-2,5-diene-7,1-cyclopropane} (I) has been investigated in the presence of Ni-, Fe-, Co-, Rh-, and Ir-based metal complex catalysts. Depending on the nature of the metal and its ligand environment cyclodimerization of (I) can take place via [2+2]-, [2+2+2]-, and [4+4]-cycloaddition schemes, to give high yields of hepta-, octa-, and nonacyclic strained hydrocarbons.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2592–2599, November, 1988.     

Geometries of excited states of small polyenes

The behaviour under rotations around one or two double bonds of the first () singlet and triplet states of small conjugated molecules have been investigated using localized Molecular Orbitals. The results obtained with a ( + ) excitonic matrix are in agreement with previous results obtained with delocalized Molecular Orbitals: 1. the rotation around one double bond is more favorable than two symmetrical rotations around two double bonds, 2. the rotation occurs around one inner double bond rather than around a terminal bond. This work shows the role played by the ( — ) mixing in the stabilization of the twisted conformations. A further optimization of the bond lengths in the excited singlet and triplet states of butadiene shows that the preferred geometry is a non symmetrical twisted geometry with different lengths for the two C=C double bonds. This symmetry instability suggests to introduce a vibronic wave-function in which the various locally excited electronic wave functions are multiplied by different vibrational wave functions corresponding to local deformations of the nuclear skeleton.     

Excited Π states of divinyl chalcogenides and chalcophenes

Electron transitions in divinyl chalcogenides (CH₂=CHXCH=CH₂, where X is S, Se, or Te) have been analyzed using UV absorption spectra of dialkyl and alkyl vinyl chalcogenides. The following relations for the orbital energies are found: ^* < ^* < ^* < ^* for Te and ^* < ^* < ^* < ^* for S and Se. For chalcophenes, a correlation between the energy of the excited state (E ^*) of specific symmetry, the ionization potential (I) and the electron affinity (EA) is obtained:E ^*=const+(I+EA)/2. The electron affinity of divinyl chalcogenides is estimated. The correlation between the excited ^* states of divinyl chalcogenides and chalcophenes is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 831–835, May, 1994.     

Structure électronique du fluoroacétylène et du chloroacétylène

Résumé La structure et le spectre électronique du fluoroacétylène et du chloroacétylène ont été étudiés à l'aide d'une méthode matricielle du type LCAO SCF MO où les fonctions monoélectroniques sont des orbitales orthogonalisées de Löwdin. Le transfert de charge de l'halogène au système est d'environ 0,04 électron 2p pour le fluor et 0,08 électron 3p pour le chlore. L'étude des transitions électroniques indique pour la transition du type - située vers 1850 Å un effet bathochrome et une augmentation de la force oscillatrice lorsque l'électronégativité de l'halogène décroît. Ceci permet d'identifier la transition située vers de plus grandes longueurs d'onde avec une transition - dont la force oscillatrice varie en sens inverse de celle de la transition -.

---

The electronic structure and spectra of fluoroacetylene and chloroacétylène have been studied by a matricial method of LCAO SCF MO type where the monoelectronic functions are Löwdin'S orthogonalized orbitals. The charge transfer from the halogen to the system is equal to about 0,04 2p electron for fluorine and to 0,08 3p electron for chlorine. A bathochromic effect and an increase of the oscillator strength with the halogen electronegativity decreasing have been found for the - transition at 1850 Å; from the theoretical results it is possible to identify the transition of lower energy as a - transition whose oscillator strength varies the other way than that of the - transition.

---

Zusammenfassung Struktur und Elektronenspektren von Fluor- und Chloracetylen wurden mit Hilfe einer Matrizenmethode vom LCAO-SCF-MO-Typ untersucht, wobei die Einelektronenfunktionen nach Löwdin orthogonalisiert wurden. Der Ladungsübergang vom Halogen zum -System entspricht etwa 0,04 2p-Elektronen bei Fluor und 0,08 3p-Elektronen bei Chlor. Für den --Übergang um 1850 Å wird für abnehmende Elektronegativität des Halogens eine bathochrome Verschiebung und eine Zunahme der Oscillatorenstärke gefunden. Das erlaubt, die längerwellige Bande einem - -Übergang zuzuordnen, dessen Oscillatorenstärke sich in entgegengesetzter Richtung ändert.

---

---

Nous tenons à remercier Monsieur Berthier pour de nombreuses discussions sur ce travail, Messieurs Romanet et Wojtkowiak pour avoir attiré notre attention sur les problèmes posés par les spectres ultraviolets des halogéno-acétyléniques et Monsieur H. v. Hirschhausen pour nous avoir signalé une erreur numérique dans la fin de cet article.     

Electronic structure of monosubstituted benzenes and X-ray emission spectroscopy

The electronic structure of the benzaldehyde molecule has been studied by X-ray emission spectroscopy. The gas-phase O-K- and C-K-spectra of this compound have been obtained. MNDO quantum-chemical calculations have been carried out. The structure of the MO's of benzaldehyde has been compared with those of benzene and formaldehyde molecules. The character of the p-p interaction of the phenyl and formyl fragments has been considered. The contribution of the latter to the highest occupied molecular orbitals of the-system has been shown to be small.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1033–1037, June, 1994.     

The Effect of cis-trans Isomerism on the Electronic-vibrational Structure of the Ground and Excited States and Reactivity of 2-(2-Furyl)- and 2-(2-Thienyl)oxazole

The fluorescent properties, structure, and electronic structure of the ground and excited singlet and triplet electronic states of the cis and trans forms of 4,5-dihydro-2-(2-furyl)oxazole, 4,4-dihydro-2-(2-thienyl)oxazole, 2-(2-furyl)oxazole (FO), and 2-(2-thienyl)oxazole (TO) have been studied. The orbital nature of the lower excited singlet and triplet states has been studied by the semiempirical INDO/S (valence approximation) and PPP/S ( approximation) methods. It was shown that for FO and TO molecules the lower triplet state is of the * type, for which delocalization of the electronic excitation on atoms is characteristic. In the singlet excitation state inversion was observed of the energy levels of the delocalized * states and n* states localized over several bonds (for the free TO and FO molecules the lower excited singlet states S₁* were assigned to * and n* types respectively). Owing to the low position of the T * and T _n* levels relative to the singlet level of * type, the rate constant for intercombination conversion is greater than the rate constant for radiative decay. Consequently an efficient population of the triplet states of the molecules occurs under conditions of electronic-vibrational excitation. The direction of reactions during synthesis was compared with the localization indices in the ground state for electrophilic, nucleophilic, and radical substitution, and also with the excitation localization numbers L for a wide selection of electronically excited states. It was concluded that the change in the structure of the azole molecule on replacing an O atom by an S atom, or on changing from a partially hydrogenated to a heteroaromatic system, was the main reason for the change of all the spectral parameters characterizing the electronic-vibrational or the spin-orbital interaction of the most reactive groups of atoms in the molecular structure.     

Ionic character

The concept of ionic character in and bond systems is considered in the light of recent definitions of orbital electronegativity [6, 14].

---

Zusammenfassung Das Konzept des ionischen Charakters in und Bindungen wird im Lichte neuerer Definitionen von Orbitalelektronegativitäten diskutiert.

---

Résumé Le caractère ionique des liaisons et est discuté en tenant compte des définitions récentes de l'électronégativité des orbitales.

---

---

We wish to acknowledge financial support from the National Research Council of Canada. One of us (N.C.B.) thanks the council for the award of a studentship.     

The UV spectra of arsines and arsine selenides

Short-wavelength n_Se ^* and long-wavelength n_Se ^* bands are observed in the UV spectra of saturated trialkylarsine selenides in the near-UV region. The n_x ^* band in going from arsine selenides to arsine sulfide and then to arsine oxides is shifted hypsochromically, as in the corresponding phosphorus compounds. The n_x ^* band is only slightly sensitive to the chalcogen. Saturated trialkylarsines, in contrast to alkylphosphines, absorb in the near UV region (the n_As ^* band is at 208 nm).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 940–942, April, 1990.     

Quantum-chemical study of manifestations of conjugation in molecules containing conjugated C=C and C=O bonds

Based on the MNDO calculations of the electronic structure of the molecules of acrolein, glyoxal, and butadiene, possible mechanisms of the conjugation in systems containing conjugated C=C and C=O bonds have been analyzed. In the electronic ground state ofs-trans-acrolein, the , -conjugation is very small, whereas in the first excited electronic state, the conjugation is substantial, In the ground state ofs-trans-glyoxal, the ,-conjugation should manifest itself clearly but should be weaker than in butadiene, whereas in the first excited electronic state, this conjugation should be more pronounced, Alternation of double and single bonds in the classic structural formula of a molecule does not ensure that this molecule exhibits the properties of a -conjugated system even in planar conformations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1648–1652, July, 1996.     

Molecular orbital calculations on the optical rotatory properties of chiral allene systems

The chiroptical properties associated with the ^* transitions in dissymmetric allene systems are calculated and relationships between the chiroptical observables and the stereochemical and electronic structural features of these systems are examined. The calculations are based on the INDO and CNDO/S semiempirical molecular orbital models for the electronic structure of the molecular systems and excited states are constructed in the virtual orbital-configuration interaction approximation. The dipole strengths, rotatory strengths, and dissymmetry factors for the three lowest energy ^* transitions are computed and reported for eleven chiral allene structures. Relationships between absolute configuration and the signs of the ^* rotatory strengths are examined and discussed.     

Ab initio SCF and CI study of the electronic spectrum of pyridine N-oxide

Configuration interaction (CI) studies of ground, n *, * * electronically excited states are reported for pyridine N-oxide. The transition energy to the lowest * excited ¹ B ₂ state is calculated at 4.35 eV, compared to the experimental spectrum range of 3.67–4.0 eV. This state lies below the lowest n * excited ¹ A ₂ state calculated at 4.81 eV above the ground state. The only experimentally reported triplet state at 2.92 eV above the ground state is predicted to be the ³ A ₁ (*) state. The calculated energy lies at 3.27 eV. Numerous other high-lying singlet states as well as the triplet states have also been calculated. The intramolecular charge transfer character of the ground and the excited states have been studied in terms of the calculated dipole moment and other physical properties.     

Spectroscopic study of compounds possessing a bond of an element of group IVb to hydrogen

Conclusions In the silanes (C₂H₅)X₃SiH and X₃SiH, the substituants X of which form d-p bonds with the silicon atom, the effect of d-p conjugation depends on the inductive and mesomeric effects of X, which change the charge on the silicon atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 342–347, February, 1972.The authors would like to express their gratitude to G. A. Domrachev for discussing certain questions in this article.     

σ-π separation: Excited H2 as a model system

The low-lying states of H₂ consist of one core () and one valence () electron and afford a direct evaluation of intershell - interaction. After resolution of the electronic energy into only, only, and - parts, it is shown that an electronic change in this model system is due solely to a change in the electrons. Simple Hückel theory is examined. If the molecular core is represented properly, regardless of the wave function the calculated and parameters are in reasonable agreement with the empirical parameters. This agreement appears to be due to a fortuitous cancellation of energy contributions.

---

Zusammenfassung Die niedrig liegenden -Zustände des H₂ bestehen aus einem Rumpfelektron und einem Valenzelektron und ermöglichen eine direkte Auswertung der --Wechselwirkung zwischen zwei Schalen. Nach der Zerlegung der elektronischen Energie in -,- und --Anteile wird gezeigt, daß eine elektronische Veränderung in diesem Modellsystem nur auf eine Veränderung des -Elektronenanteils zurückgeht. Die einfache Hückeltheorie wird untersucht. Wenn der Molekülrumpf geeignet dargestellt wird, so sind, unabhängig von der -Wellenfunktion, die berechneten Parameter und in guter Übereinstimmung mit den empirischen Parametern. Diese Übereinstimmung scheint auf eine starke Auslöschung von Energieanteilen zurückzugehen.

---

Résumé Les états inférieurs de H₂ consistent en un électron de coeur () et un électron de valence () et fournissent une évaluation directe de l'interaction entre couches -. Après expression de l'énergie électronique en parties , et -, on montre qu'une modification électronique de ce système modèle est due seulement à une modification des électrons . La théorie de Hückel simple est examinée. Si le coeur moléculaire est convenablement représenté, quelle que soit la fonction d'onde , les paramètres at calculés sont en accord raisonnable avec les paramètres empiriques. Cet accord apparaît comme le résultat d'une compensation fortuite de contributions énergétiques.

---

---

Work performed in part under the auspices of the U.S. Atomic Energy Commission.

---

Work aided by the U.S. Public Health Service via grant GM 08068.     

New synthesis of iridicinium salts

Conclusion -Cyclopentadienyl--(1,2-diphenylcyclopentadienyl)iridium fluoborate was obtained by reacting tolan with -allyl--cyclopentadienyliridium chloride in the presence of silver fluoborate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1412–1414, June, 1982.The authors wish to thank A. I. Lutsenko and A. S. Shashkova for taking the PMR spectra.