From small structural modifications to adjustment of structurally dependent properties: 1‐methyl‐3,5‐bis[(E)‐2‐thienylidene]‐4‐piperidone and 3,5‐bis[(E)‐5‐bromo‐2‐thienylidene]‐1‐methyl‐4‐piperidone

The molecules of the title compounds, C₁₆H₁₅NOS₂, (I), and C₁₆H₁₃Br₂NOS₂, (II), are E,E‐isomers and consist of an extensive conjugated system, which determines their molecular geometries. Compound (I) crystallizes in the monoclinic space group P2₁/c. It has one thiophene ring disordered over two positions, with a minor component contribution of 0.100 (3). Compound (II) crystallizes in the noncentrosymmetric orthorhombic space group Pca2₁ with two independent molecules in the unit cell. These molecules are related by a noncrystallographic pseudo‐inversion center and possess very similar geometries. The crystal packings of (I) and (II) have a topologically common structural motif, viz. stacks along the b axis, in which the molecules are bound by weak C—H...O hydrogen bonds. The noncentrosymmetric packing of (II) is governed by attractive intermolecular Br...Br and Br...N interactions, which are also responsible for the very high density of (II) (1.861 Mg m⁻³).     

Unexpected reaction of 1,1,1,10,10,10-hexafluorodecane-2,4,7,9-tetrone with methyl trifluoroacetate

Hexane-2,5-dione or 1,1,1,10,10,10-hexafluorodecane-2,4,7,9-tetrone react with methyl trifluoroacetate in the presence of LiH to give, upon treatment with diluted acid, 6-hydroxy-9-oxo-2,4,10-tris(trifluoromethyl)-3,11,12-trioxatetracyclo[5,2,1,0^2,6,0^4,10]dodecane. The structure of this compound was determined by X-ray diffraction study.     

Nonstationary polaron

We define the Bogoliubov group variables for the space-time translations in the secondarily quantized system. We propose a scheme for quantizing a scalar field that has a nonzero classical component and interacts with a charged scalar field. The polaron is treated as a result of the interaction of the charged particle with the classical component of the neutral field. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 122, No. 3, pp. 417–425, March, 2000.     

Parameters of anisotropic atomic displacements in chemical compounds as criteria for chemical bond types

Analysis of the parameters of anisotropic atomic displacements in various chemical compounds reveals a feature characteristic of a donor-acceptor bond: the ellipsoids of anisotropic displacements of the atoms involved in this bond are elongated in the direction of the bond. The explanation of the effect observed is proposed.     

First platinum(ii)–alkaline-earth acetate-bridged complexes Ptii(m-OAc)4Mii(AcOH)4 (M = Ca,Sr, Ba)

1. Download high-res image (119KB)
2. Download full-size image

     

Synthesis and crystal structure of a new hybrid methylammonium iodocuprate

1. Download high-res image (88KB)
2. Download full-size image

     

Heteroorganic betaines

The [Ph₃P⁺−CMe₂−SiMe₂−SEt]Br⁻ salt was prepared by the reaction of betaine Ph₃P⁺−CMe₂SiMeR−S⁻ (1a: R=Me) with EtBr. Acetylation of betaine1a or Et₃P⁺−CHMeSiMe₂−S⁻ (2a) afforded 2,2,6-trimethyl-1,3-dioxa-2-silacyclohex-5-ene-4-thione      

Heteroorganic betaines

Photolysis and thermal decomposition of betaines R₃P−CR¹R²−SiR³R⁴−S⁻ (1) follows two main pathways: (a) a Corey—Chaykovsky type reaction with elimination of Ph₃P and generation of silathiirane (2) and (b) a retro-Wittig type reaction accompanied by elimination of R₃P=CR¹R² and generation of silanethione R³R⁴Si=S (3). Highly reactive compounds2 and3 undergo subsequent transformations to give derivatives of tetrahydro-1,4-dithia-2,5-disilin, 1,3-dithia-2,4-disilolane, and phosphonium salts ofsymm-tetraorganodisilthiane dithiolates [Ph₃P⁺CHR¹R²]₂[(R³R⁴SiS⁻)₂S]. The structures of the compounds obtained were established by X-ray diffraction analysis and multinuclear NMR spectroscopy. For part 3, see Ref. 1. The betaines Et₃P⁺CHMeSiMe₂S⁻ and Et₃P⁺CHMeSiPh₂S⁻ with alkyl groups at the phosphorus atom are distinguished by high thermal stability; their spectral characteristics do not change during storage of solutions of these compounds in pyridine-d₅ or metastable solutions in benzene-d₆ for 1–2 years at −20°C in sealed evacuated tubes or on heating (150°C) for 15 h. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1594–1603, September, 2000.     

Novel reactions of arylmalonate carbanions. The reaction with phenyl isocyanate resulting in carbamates by 1,3-C→N migration of the ethoxycarbonyl group

The reactions of carbanions of diethyl phenyl and 4-nitrophenylmalonates with phenyl isocyanate occur with 1,3-C→N migration of the ethoxycarbonyl group to form the corresponding adducts. The introduction of NO₂ groups into the benzene ring of arylmalonates inhibits the reaction. Dedicated to Academician V. A. Tartakovsky on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1608–1610, August, 2007.     

Unusually ready hydrolysis of nitrile groups in 1,1,2,2-tetracyanoethane by pyruvic acid

A scheme for the unusually ready selective hydrolysis of three of the cyano groups in 1,1,2,2-tetracyanoethane to 2-cyanoethane-1,1,2-tricarboxamide by the action of pyruvic acid was proposed. Only one cyano group undergoes hydrolysis in the reaction with sodium pyruvate. In the course of this reaction, 2-amino-5-methyl-3, 4-dicyano-4,5-dihydrofuran-4,5-dicarboximide, the structure of which was determined by x-ray diffraction investigation of the monocrystal, is formed. I. N. Ul'yanov Chuvashsk State University, Cheboksary 428015. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1472–1476, November, 1997.