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The complexes of group 13 element trispentafluorophenyl derivatives E(C6F5)3 (E = B, Al, Ga, In) with diethyl ether of 1:1 composition have been synthesized and structurally characterized. All compounds are isostructural. Thermal stability studies reveal that at elevated temperatures all complexes decompose with pentafluorobenzene evolution. The geometries and thermodynamic characteristics for the dissociation reactions of the compounds have been computed using three DFT methods. The 1H NMR α‐proton chemical shifts for the coordinated ether in deuteriobenzene and in CD2Cl2 solutions correlate with gas phase dissociation enthalpies of the complexes. Potentially high Lewis acidity of B(C6F5)3 is hindered by the large pyramidalization energy of the acceptor moiety.

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Complexes formed by interaction of E(C6F5)3 (E = B, Al, Ga, In) with excess of acetonitrile (AN) were structurally characterized. Quantum chemical computations indicate that for Al(C6F5)3 and In(C6F5)3 the formation of a complex of 1:2 composition is more advantageous than for B(C6F5)3 and Ga(C6F5)3, in line with experimental observations. Formation of the solvate [Al(C6F5)3·2AN]·AN is in agreement with predicted thermodynamic instability of [Al(C6F5)3·3AN]. Tensimetry study of B(C6F5)3·CH3CN reveals its stability in the solid state up to 197 °C. With the temperature increase, the complex undergoes irreversible thermal decomposition with pentafluorobenzene formation.

Ab initio calculation of spin-spin coupling constants 13 C 13 C for a series of ketone oximes was carried out in a framework of the second order polarization propagator approximation (SOPPA). Taking into account the electron correlation effects and the use of special correlation-consistent basic sets including functions allowing for internal correlation and dense functions provided a good agreement between the calculated and experimental values. These results open new possibilities for the configurational assignment of imine nitrogen compounds.Oximes are important semiproducts in the preparative organic sunthesis [1]. In recent years considerable study has been given to ketone oxime reactions with acetylene in superbasic media resulting in O-vinyloximes, pyrroles, and N-vinylpyrroles (Trofimov reaction) [2]. Trofimov reaction ensures an elegant way to previously unavailable or unknown compounds of pyrrole series, and the corresponding yields depend on the structure and configuration of initial oximes. Therefore the estimation of oxime configuration is among the most important problems of pyrrole synthesis [3]. The problems of oximes configuration is also extremely interesting because their isomers differ not only in physical constants but at the same time in chemical properties [4].The configurational structure of imine nitrogen compounds can be unambiguously assigned basing on the measurement the 13 C 13 C coupling constants in the NMR spectra for these values are very sensitive to the orientation of the lone electron pairs (the so-called LEP effect [5]). It was shown theoretically [6] that the LEP effect on the 13 C 13 C coupling constants consisted in a throughspace interaction of the lone electron pair of a heteroatom with a bonding and antibonding orbitals of the neighboring carbon-carbon bonds resulting respectively in an increase and decrease in the s-character of these bonds, i.e., in a positive and a negative contribution into the corresponding J CC constants. The observed stereospecificity of the carbon-carbon coupling constants in oximes and their derivatives makes it possible to use the LEP effect as a reliable and universal criterion for assignment of their configurational isomers [5].A reliable and economical procedure for nonempirical calculation of coupling constants of medium size organic molecules was reported in [7]. The method provides wide prospects for the use ab initio calculations in the theoretical study of the mechanism of the spin-spin coupling. The main goal of the present study is elucidation of the possibility to use procedure [7] for calculation of 13 C 13 C coupling constants in molecules containing multiple bonds and heteroatoms with lone electron pairs. In particular, we were interested whether the LEP effect would be reproduced by nonempirical calculations of 13 C 13 C coupling constants, and also whether this method would be promising for establishing the configuration of imine nitrogen compounds of unknown structure.Here we report the results of ab initio calculations ...