ELECTRONIC STRUCTURE AND CHEMICAL BOND IN 9,9,10,10-TETRAETHYNYL-9,10- DIHYDRODISILAANTHRACENE

Journal of Structural Chemistry - Atomic and electronic structures of cyclic organosilicon compound 9,9,10,10-tetraethynyl-9,10-dihydrodisilaanthracene are studied by the density functional theory....     

Synthesis,molecular and crystal structure of new 9,10-substituted deazaflavins

Cyclocondensation of 6-N-(3-hydroxypropyl)aminouracyl with 2-fluoro- or 2,3-dimethoxy-substituted benzaldehydes provided the corresponding 9,10-substituted 5-deazaflavins {pyrimido[4,5-b]quinoline-2,4-(3H,10H)diones}. X-ray diffraction analysis was carried out for 9-methoxy-10-(3-hydroxy-propyl)-substituted 5-deazaflavin derivative.     

Molecular and crystal structure of sophoridine

The three-dimensional structure of the alkaloid sophoridine C₁₅H₂₄ON₂ has been studied by x-ray structural analysis; the parameters of the elementary cell are: a=5.458, b=10.640, c=11.989 Å; =99.7°; z=2; space group P2₂. The experimental set was obtained on a Sinteks-P2₁ diffractometer, the structure being determined by the direct method with refinement by the method of least squares in the anisotropic approximation taking the hydrogen atoms into account to R=0.059. Ring A has the chair conformation, rings B and C the boat conformation, and ring D the half-chair conformation. The linkages of rings A/B, B/C, and C/D are trans, and of B/C cis. There are no shortened intermolecular contacts in the crystal structure of the compound.Institute of Bioorganic Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Institute of Crystallography, Academy of Sciences of the USSR, Moscow. V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 355–362, May–June, 1979.     

Molecular and crystal structure of tetrahydroneosophoramine

The structure of tetrahydroneosophoramine has been studied by x-ray structural analysis. Rings A, B, and C have the chair conformation, and ring D the half-chair conformation. On the basis of a semiquantitative analysis it has been shown that the strains in the molecules of tetrahydroneosophoramine and of matrine are of the same order of magnitude.Institute of Bioorganic Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Institute of Crystallography, Academy of Sciences of the USSR, Moscow. V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 751–757, November–December, 1981.     

Molecular and crystal structure of tetrahydroneosophoramine

The structure of tetrahydroneosophoramine has been studied by x-ray structural analysis. Rings A, B, and C have the chair conformation, and ring D the half-chair conformation. On the basis of a semiquantitative analysis it has been shown that the strains in the molecules of tetrahydroneosophoramine and of matrine are of the same order of magnitude.     

Molecular and crystal structure of tert-butylphosphaethyne

The crystal and molecular structure of tert-butylphosphaethyne, Bu^tCP, liquid at room temperature, has been determined by X-ray diffraction at 108 K. Main geometrical parameters are as follows: PC 1.542(2), C(sp)–C(sp³) 1.470(3) Å, PCC 179.3(2)°.     

Molecular and crystal structure of luteidine

The crystal structure of luteidine has been deciphered by x-ray structural analysis; there are two molecules in the independent part of its elementary cell. These symmetrically independent molecules differ in structure. The position of the olefinic methoxy group of luteidine has been established. Its structure has been determined as 1-hydroxy-2,12-dimethoxy-9,10-dihydrohomoaporphine.Institute of Biorganic Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent, and V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 348–352, May–June, 1986.     

Synthesis and some chemical properties of 4-acyl-2,6-disilapiperazines. Molecular and crystal structure of 4-formyl-2,2,6,6-tetramethyl-2,6-disilapiperazine

An one-pot synthesis of 4-acyl-2,6-disilapiperazines has been developed which consists of treatment of carboxamides with hexamethyldisilazane and dimethylchloromethylchlorosilane mixture with subsequent amination of the intermediate N,N-bis(dimethylchlorosilylmethyl)amides (which are derivatives of pentacoordinated silicon) with ammonia or primary amines. The hydrolytic stability of the 4-acyl-2,6-disilapiperazines and their reactions with benzenesulfonamide have been studied. The structure of 4-formyl-2,2,6,6-tetramethyl-2,6-disilapiperazine has been confirmed by X-ray diffraction analysis.Russian State Medical University, Moscow 117869, Russia     

Facile synthesis of 2,3,7,8-tetramethyl-2,2′-dipyrrin trifluoroacetate and its X-ray crystal structure

3,4-Dimethyl-1H-pyrrole-2-carboxylic acid was converted to 2,3,7,8-tetramethyl-2,2′-dipyrrin by the action of trifluoroacetic acid and ethyl orthoformate. A crystal of the dipyrrin was grown from dichloromethane-n-hexane and an X-ray crystallographic structure of its trifluoroacetate salt was determined. Correspondence: David A. Lightner, Department of Chemistry, University of Nevada, Reno, Nevada 89557-0020, USA.     

Molecular and crystal structure of sophoridine N-oxide

The spatial structure of natural sophoridine N-oxide has been studied by x-ray structural analysis. It has been shown that when sophoridine is oxidized, rings B and C, which have the boat form, are deformed in the direction of the twist form.