On the symmetry of iron(III) tris-acetylacetonate crystals

The crystal structure of iron tris-acetylacetonate is re-determined. Crystal data at 293 K are: a = 15.4524(5) Å, b = 13.5876(4) Å, c = 16.5729(7) Å, Z = 8; at 150 K: a = 15.2541(4) Å, b = 13.4451(3) Å, c = 16.4256(5) Å, Z = 8. The structure is molecular and comprises isolated molecules. The coordination polyhderon of iron is an almost regular octahedron, Fe-O bond lengths are 1.977–2.003 Å (293 K) and 1.982–2.006 Å (150 K). In the crystalline state, the molecules are arranged in layers, and iron atoms are located on a plane yielding an almost regular trigonal net with the Fe...Fe separations of 7.558–8.103 Å (293 K) and 7.472–8.017 Å (150 K). The adjacent layer is positioned exactly over the first one with a Fe...Fe distance of 8.303 Å (293 K) and 8.236 Å (150 K).     

Analysis of the interaction kinetics of two phases in a binary system. Formulation of the problem,model, and method

An approach to the analysis of the interaction kinetics of two phases in a binary system is outlined, on the basis that: 1) the rates of transfer of the matter of the components through the phase boundary, the rates of boundary motion, and the diffusional flux densities in the boundary layers are represented as explicit functions of the boundary concentrations of foreign components in the phases c ^B and c ^A ; 2) the features of the system behavior in various regions of the field of values of c ^B and c ^A are considered; 3) the trajectory of the process in the space of the parameters c ^B and c ^A is determined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 43–49, June, 1985.     

Paths for the formation of dioxin-type xenobiotics: Quantum-chemical treatment 1. Formation of polychlorobiphenylenes from polychlorobenzenes

The heats of formation of polychloroarynes (PCA's) from polychlorobenzenes (PCB's) have been calculated by the AMI method as a function of the composition and structure of the PCB's according to a two-step scheme including deprotonation with the formation of carbanions (PCCA's, H₁) and dechlorination to PCA's (H₂). The influence of the solvent on H₁ and H₂ has been evaluated in the framework of the solvaton model. It has been shown that the value of H₁ decreases as the number of C1 atoms in the PCB is increased, while H₂ increases along the same series due to the increase in the relative stability of the PCCA as the number of C1 atoms is increased. Although the dimerization of PCA's with the formation of polychlorobiphenylenes (PCBP's) is forbidden by orbital symmetry rules, calculations of fragments of the potential-energy surface have shown that this reaction takes place with an energy barrier amounting to about 1 kcal/mole.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Institute of Organic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 350–355, February, 1992.     

Calculation of the proton affinities of polyfluorobenzenes and the activation energies for 1,2-hydrogen shifts in their carbocations

Isolated polyfluorobenzene (PFB) molecules and their protonated forms are investigated by the AM1 method with full geometry optimization. The proton affinities of PFB are estimated for different protonated positions. The proton affinity of PFB averaged over all isomers is shown to decrease monotonically as the number of fluorine atoms in the molecule increases. The relative populations of different isomers of arenonium ions (AI) formed by PFB protonation are determined. From the calculated data, the value of ⁺ for the F atom in theipso-position is estimated as 1.00. The activation energies of the 1,2-hydrogen shifts in AI are calculated. The dependences of the proton affinity and the activation energies of 1,2-hydrogen shifts on the number of halogen atoms are found to have distinct characters for PFB and polychlorobenzenes. The physical reasons for these difference are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1878–1882, November, 1993.     

Energy estimate of bond polarity

Conclusions The bond polarity, determined as the ionic component fraction of the bond energy, is related in a linear manner to the Pauling polarity value.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No, 10, pp. 2401–2402, October, 1982.The author thanks I. V. Stankevich for discussing the work.     

Chemistry of indole

,-Unsaturated ketones form pyrimido[1,2-a]indoles with 2-aminoindole, while 1-alkyl-2-aminoindoles under these conditions are converted to the corresponding -carbolines. The structures of the compounds obtained were confirmed by alternative synthesis.See [1] for communication XIX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 61–64, January, 1971.