A new method for generating organosilanones

A new method for the generation of organosilanones by the reaction of betaines, R₃P⁺-CR¹R²-SiR³R⁴-S^–, with (Et₃Sn)₂O was suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2246–2247, December, 1994.This study was financially supported by the Russian Foundation for Basic Research, Project No. 94-03-09710.     

Status and prospects of VEPP-2000 electron-positron collider

High energy physics experiments were started at VEPP-2000 at the end of 2010; the third experimental run was finished in July 2013. The last run was devoted to the energy range 160–510 MeV in a beam. Compton backscattering energy measurements were used for the regular energy calibration of the VEPP-2000, together with resonance depolarization and NMR methods. The conception of the round colliding beam lattice along with precise orbit and lattice correction yielded a record high peak luminosity of 1.2 × 10³¹ cm^?2 s^?1 at 510 MeV and an average luminosity of 0.9 × 10³¹ cm^?2 s^?1 per run. A total betatron tune shift of 0.174 was achieved at 392.5 MeV. This corresponds to the beam-beam parameter ξ = 0.125 in terms of the collision point. The injection system is currently modernized to allow injection of particles at the VEPP-2000 energy maximum and the elimination of the existing lack of positrons.     

Germanium carboxylates: the first X‐ray diffraction study of germanium(II) dicarboxylate and germanium(IV) tetracarboxylate

Germanium(II) dipropionate (1) has been synthesized and its crystal structure, as well as that of germanium(IV) tetrapropionate (2), has been determined. By contrast to monomeric 2 with monodentate propionate ligands, compound 1 is associated, forming a cyclotetramer [Ge(O₂CEt)₂]₄ (1a) via intermolecular dative C?O → Ge interactions. Copyright © 2005 John Wiley & Sons, Ltd.     

Recommissioning the Modernized VEPP-2000 Electron–Positron Collider

The VEPP-2000 electron–positron collider has been operating at the Budker Institute of Nuclear Physics (BINP) since 2010. Applying the concept of round colliding beams allowed the record value of the beam–beam parameter ξ ～ 0.12 to be reached. The upgrading of the VEPP-2000 complex, including the connection to the new BINP Injection Complex and modification of the electron–position booster and the BEP–VEPP-2000 transfer channels to work at 1 GeV, resulted in a significant increase in luminosity. Work on statistical data collection using detectors is in progress.     

The germanium(II) ate complex [Ph3PiPr][Ge(OCOMe)3]: the first structurally characterized compound containing a discrete [E14(II)O3](−) (E14(II) = Si,Ge, Sn or Pb) anion

An X‐ray diffraction study reveals an unusual structure of the new thermally stable germanium(II) ate complex [Ph₃PⁱPr][Ge(OAc)₃] (4) containing a discrete [Ge(OAc)₃]^(?) anion containing monodentate acetate ligands with a trigonal pyramidal germanium centre. Copyright © 2005 John Wiley & Sons, Ltd.     

X-ray diffraction study of the first monomeric dioxygermylene Ge(OCH2CH2NMe 2)2 stabilized by two Ge ← N intramolecular coordination bonds: The influence of Ge ← N intramolecular coordination bonds on the structure and packing of molecules in crystals

The molecular and crystal structures of the first monomeric dioxygermylene Ge(OCH₂CH₂NMe ₂)₂ (I) stabilized by two Ge ← N intramolecular coordination bonds are determined by X-ray diffraction analysis. The Ge ← N bond lengths in two independent molecules are equal to 2.329(2), 2.337(2) and 2.324(2), 2.346(2) Å, respectively. The central germanium atom plays the role of a spiro atom between two five-membered heterocycles in the envelope conformation and adopts a trigonal-bipyramidal configuration with a lone electron pair in the equatorial position. Compound I has two planar-chiral isomers which crystallize jointly. Molecules in the crystal have a layered packing (molecular layers are perpendicular to the [001] direction) composed of four translationally independent equivalent layers. These layers are spaced at 1/4c intervals and displaced with respect to each other by approximately +0.35a, ?1/4b, ?0.35a, and +1/4b, respectively. The characteristic displacement of the layers and their proper symmetry (pba2) that differs from the symmetry of the crystal (space group P2₁2₁2₁) determine a large variety of pseudosymmetry operations.     

Measurement of the cross section for the e + e ? → ωπ0 → π0π0γ process in the energy range of 1.1–1.9 GeV

The cross section for the e ⁺ e ^? ?? ???⁰ ?? ??⁰??⁰?? process has been measured in the energy range of 1.1?C1.9 GeV. The measurement has been made with the Spherical Neutral Detector at the VEPP-2000 e ⁺ e ^? collider. The data in the energy range of 1.1?C1.4 GeV are in agreement with the earlier measurements with the SND and CMD-2 detectors. The cross section has also been measured above 1.4 GeV.     

New stable germylenes,stannylenes, and related compounds 7. Synthesis and structures of compounds Hal—Sn—OCH<Subscript>2</Subscript>CH<Subscript>2</Subscript>NMe<Subscript>2</Subscript> (Hal = Cl or F)

New stable divalent tin derivatives containing no bulky substituents at the metal atom, Hal—Sn— OCH₂CH₂NMe₂ (Hal = Cl or F), were synthesized, and their crystal structures were studied by X-ray diffraction. Unlike the analogous monomeric divalent germanium derivative Cl—Ge—OCH₂CH₂NMe₂, the new compounds are centrosymmetric dimers formed via two intermolecular Sn←CO coordination bonds. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 259–262, February, 2007.