New organic two-dimensional metals, (ET)4(Hg2X6)·PhCl (X=Cl,Br)

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2872–2873, December, 1990.     

Complexes of arenechromium compounds with 7,7,8,8-tetracyanoquinodimethane

Conclusions For the first time complexes of arenechromium compounds with 7,7,8,8-tetracyanoquinodimethane were obtained.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2124–2125, September, 1968.     

Reduction of rhodium(III) trifluoroacetate by norbornadiene

It was shown that the action of heat on rhodium(III) trifluoroacetate with norbornadiene (NBD) leads to its reduction and the formation of red crystals of [Rh(CF₃COO)NBD]₂. The formation of the complex was confirmed by elemental analysis and IR, electronic, and x-ray photoelectron spectra. The reaction shows that Rh-Rh compounds can disproportionate under the influence of NBD with the formation of Rh(I) and Rh(III).Institute of Chemical Physics at Chernogolovka, Russian Academy of Sciences, 142432 Chernogolovka. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1438–1440, June, 1992.     

The study of molecular motions in substituted ferrocenes by means of NMR spectroscopy

The proton magnetic resonance spectra for ferrocene derivatives have been investigated in the solid state at a frequency of 27.5 MHz and at temperatures within the range 4.2–300 K. Evidence for re-orientation in various substituent groups and cyclopentadienyl rings has been deduced on the basis of the temperature dependence of the second moment of the PMR lines. The experimentally observed decrease in the second moment has been compared with the calculated contributions of different molecular groups to the second moment thus enabling an identification of these groups. In computing the second moment, account has been taken of both intra- and intermolecular dipole-dipole interactions. It is shown that the introduction of substituents into some ferrocene rings affects the magnitude of the re-orientation energy for both the substituted and unsubstituted rings. The change of the re-orientation energy of the substituted and unsubstituted rings in substituted ferrocenes with the structure and electronic properties of the substituents is discussed.     

Synthesis of diquinone derivatives of deuteroporphyrin ix for the study of the first stage in the process of photosynthesis

Diquinone derivatives of deuteroporphyrin IX containing covalent bridges of different lengths between the chromophores have been synthesized. The compounds were prepared by the condensation of hydroxy-quinones with deuteroporphyrin IX using a mixed anhydride method which employed the system di-tert-butyl pyrocarbonate — 4-dimethylaminopyridine. A spectral study of the resulting porphyrin-quinones was carried out.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 176–182, February, 1992.     

Low-temperature NMR investigation of iminoxyl radicals

By analysis of proton magnetic resonance spectra recorded at 4.2 and 3 K, the isotropic and anisotropic constants for the coupling of the unpaired electron with all the protons were determined for two investigated radicals. On the basis of these results, conclusions were reached on the spin density distribution and on the participation of the unpaired electron in hydrogen bond formation.We express our sincere gratitude to I. F. Shchegolev for useful discussions.     

X-ray structure of the organic conductor (ET)8[Hg2Br6·PhBr]2

The electrochemical oxidation of ET [bis(ethylenedithio)tetrathiafulvalene] in bromobenzene (electrolyte Bu ₄ N[HgBr ₃ ]) gave the radical-cation salt (ET) ₈ [Hg ₂ Br ₆ ·PhBr] ₂ (1), a new organic metal with a temperature range of 300–125 K. At 125 K a metal—dielectric transition is observed. Crystallographic data for (1):a=19.171(6),b=12.668(4),c=17.777(6) Å, =118.03(3), =89.45(2), =101.21(3)°, P ,Z=1,d _calc=2.30 g/cm ³ . The crystal structure of (1) is laminar. In the conducting organic layer the ET radical cations are linked into bands by shortened intermolecular S···S contacts of the side-to-side type. The anionic layer consists of centrosymmetric complexes [Hg ₂ Br ₆ ·C ₆ H ₅ Br] ₂ ^4– . The Hg ¹ and Hg ² atoms are characterized by a trigonal configuration of the Hg-Br bond which is built up, on account of secondary Hg···Br interactions, into trigonal-bipyramidal for Hg ¹ and trigonal-pyramidal (tetrahedral) for Hg ² . Interaction between the anionic and cationic layers is effected through Br ⁶ ...S ⁸ contacts [3.491(7) Å)].Institute of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 894–902, April, 1992.