Substituent Effects in S- and Se-Centered Radical Cations

The first ionization potentials of molecules XZY and 1,4-XC₆H₄ZR (X, Y are inorganic, organo- metallic, or organic substituents; Z = S, Se), as well as the energies of charge-transfer bands in the electronic spectra of tetracyanoethylene complexes of these molecules are determined by the inductive, resonance, and polarization effects of substituents X and Y. Z-Centered radical cations formed both from individual molecules in the gas phase and from those incorporated in tight radical ion pairs in solutions are closely allied in their electronic structure. The resonance parameters ⁺ _R of organosilicon, organogermanium, and organotin substituents bound to the radical cation center Z+^· were determined.     

Mesoionic 1-amino-1,3,4-triazole-2-thiones and their azomethine derivatives

The reaction of triethylammonium salts of -acyldithiocarbazic acids with sodium chloroacetate and hydrazine leads to the formation of mesoionic 1-amino-1,3,4-triazole-2-thiones, which react with aldehydes to give the corresponding azomethine derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 424–428, March, 1976.     

Substituent effects in donor-acceptor complexes with D→A coordination bonds (D = N, O, S; A = B, Al, Ga, Sn, Sb) and related systems

The effect of substituent on the enthalpy ΔH ⁰ and free energy ΔG ⁰ of complexation, on the dipole moments of complexes μ_C and coordination bonds μ_DA, and on the degree of charge transfer Δq was analyzed for 20 series of complexes with D→A coordination bonds (D = N, O, S; A = B, Al, Ga, Sn, Sb), hydrogen bonds, and charge transfer. It was found that ΔH ⁰, ΔG ⁰, μ_C, μ_DA, and Δq depend not only on the inductive and resonance effects, but also on the polarization effect of substituents; its contribution varies in a wide range and can exceed 50%.     

UV-spectroscopic study of complex formation by certain cycloolefins with tetracyanoethylene and molecular iodine

UV spectroscopy of charge-transfer complexes (CTCs) with tetracyanoethylene (TCE) and iodine has been used to study the relative donor ability of mono- and bicycloolefins and the stability of the CTCs. The donor ability of bicycloolefins, characterized by _CT(TCE), increases with increase in ring strain. The equilibrium constants for complex formation of bicycloolefins with TCE are linearly related to the rate constants of the reaction of epoxidation by tert-butyl hydroperoxide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1314–1318, June, 1990.     

Spectroscopic study of compounds possessing a bond of an element of group IVB with hydrogen

Conclusions The frequencies of the valence vibrations of the Si-H bond in trisubstituted silanes depends not only on the inductive effect of substituents, but also on the effects of d-p interaction, ,- and p,-conjugation. An analysis was made of the relative contributions of these effects, depending on the nature of the substituent.For the preceding communications, see [1, 2].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 544–550, March, 1971.     

Correlation analysis of quantum chemical data and the polarizability effect in H-complexes

The study is concerned with analysis of the energies of formation (E), frequency shifts (Δν) in IR spectra, ionization potentials (IP) of H-complexes, hydrogen bond lengths (r), and spin densities (sd) in H-complexes involving radical cations, obtained from quantum chemical calculations for 20 series of H-complexes. It was for the first time established that the E, IP, r, and sd values and the changes in enthalpy (δH) depend not only on the inductive and resonance effects but also on the polarizability effect of the substituents bound to the donor and acceptor centers in the H-complexes. Interrelations between the polarizability effect and the molecular structure of H-complexes are considered. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 602–608, April, 2006.     

Effect of substituents on ionization potentials of phosphorus compounds. Conjugation in radical cations

The first vertical ionization potentials (I) of phosphorus compounds P(X_i)₃, OP(X_i)₃, SP(X_i)₃, (4-XC₆H₄)₃P, and PCX are related to the inductive, resonance, and polarizability parameters of inorganic, organic, and organometallic substituents X by dependences of the type I = I _H + a_I + b_R ⁺ + c, where I _H is the I value for X = H. The I values are also affected by hyperconjugation. The ratio of the contributions of the resonance (b_R ⁺) and polarizability (c) effects to the I value is determined by the degree of delocalization of the unpaired electron and the positive charge in the radical cations formed upon ionization of neutral molecules. The _R ⁺ resonance parameters of organosilicon, organogermanium, and organotin substituents bound to the P ^·+ radical cation center were calculated for the first time.     

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.