The Epimerization of Trimethylsilyl Ethers During Their Gas Chromatographic Analysis

We are grateful to the donors of the Petroleum Research Fund, administered by the American Chemical Society, to the National Science Foundation and to the Research Board of the University of Illinois for support of this research, to Dr. B. Willhalm for useful comments and to the Department of Organic Chemistry, University of Geneva, for its hospitality (1971/72).     

Quantum-chemical investigation of some oligomeric heteroaromatic compounds

Indigo and its dimer, trimer, dehydro, and leuco forms were investigated within the framework of the Pariser-Parr-Pople method. The electronic structures of the compounds in the ground and excited states and the effect of chain lengthening are discussed, and the UV absorption spectra are interpreted. Several characteristics of the chromaticity of the investigated compounds as representatives of vat dyes are examined. The estimated (from calculations) energetic favorability of the indigoid, dehydro, and leuco forms of indigo is used in discussing the observed and experimental ease of redox transformations of indigo.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 794–798, June, 1972.     

Estimating stability in the problem of reconstructing the additive type of a distribution

A numerical estimate of stability is obtained in the problem of reconstructing the additive type of a distribution via the distribution of a maximal invariant.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im V. A. Steklova AN SSSR, Vol. 61, pp. 68–74, 1976.     

Relative stability of linear and cyclic configurations of systems containing four atoms of nitrogen,carbon, or oxygen

Conclusions The present article has been devoted to an investigation of the relative stability of various conceivable structures of systems X₄ (where X=C, CH, N, or O). We regard the comparative regularities which we have discovered as reliable, in spite of the use of MHM, in which no account is taken in any explicit way of the interelectronic interaction. We have considered homoatomic systems, where, on the qualitative side many conclusions are essentially of a theoretical-group character, while from a quantitative point of view the accuracy of the results obtained is increased because of the justifiable similarities assumed in the approximations of the matrix elements (both diagonal and nondiagonal). We have also investigated the geometry of the molecules, a problem of the solution of which the MHM method (as shown by comparing this with the SSP-MO [26] method) is remarkably effective.The main results of the present work are in our view to be found in the great similarity discovered in the structures of the systems C₄H₄ and N₄ (and their appreciable difference from the structure of the O₄ molecule). Therefore, returning to the over-all problem formulated at the beginning of this article, we are able to emphasize that the hypothesis of the possible formation of the N₄ system by combination of molecular nitrogen in certain complexes of the transition metals [1] is still further confirmed.N. S. Kurnakov Institute of General and Inorganic Chemistry of the Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 10, No. 4, July–August, 1969.