The crystal and molecular structure of 1,1,2,4,4,5-hexaphenyl-1,4-diphosphoniacyclohexadiene-2,5 dibromide

The crystal and molecular structure of 1,1,2,4,4,5-hexaphenyl-1,4-diphosphoniacyclohexadiene-2,5 dibromide has been determined by a single crystal, x-ray diffraction study using diffractometer data. The compound crystallizes in the space group P2₁/_c with unit cell constants a = 8.813(1), b = 36.736(4), c = 12.478(1) Å, and β = 120.91°(1). The structure was solved by the heavy atom method and refined by block-diagonal least-squares to a final R = 0.04 for the 2761 statistically significant reflections. The structure determination shows that the central phosphonium ring is a diene and not a delocalized structure as anticipated. The ring is in the boat conformation with the axial phenyl rings aligned essentially parallel to each other and 3.55 Å apart.     

The crystals and molecular structure of 1,1,4,4-Tetraphenyl-2,5-di-(t-butyl)-1,4-diphosphoniacyclohexadiene-2,5-dichloride

The crystal and molecular structure of the title compound has been determined by single crystal, x-ray diffraction techniques. The compound crystallizes in a monoclinic space group of C2/c symmetry with four molecules in a unit cell of dimensions a = 24.578(1), b = 10.503(1), c = 17.579(1) Å and (3 = 1.30.93 ± .01°. The unit cell also contains two waters of crystallization which are involved in hydrogen bonds to the chloride ions. The central ring has been shown to be a diene which resides in a boat conformation defined by dihedral angles of 157°. The structure has been refined to a value of R = 0.08 using the 1535 statistically significant reflections measured out ot a 2θ value of 140°.     

The crystal and molecular structure of 1,1,4,4-tetraphenyl-1,4-diphosphoniacyclohexane dibromide

The crystal and molecular structure of 1,1,4,4-tetraphenyl-1,4-diphosphoniacyclohexane dibromide has been determined by a single-crystal, x-ray diffraction study using diffractometer data. The compound crystallizes in the monoclinic space group P2₁/c with unit cell constants of a = 12.777(1), b = 26.180 (2), c = 16.283 (1) Å, and β = 91.18(1)°. The structure was solved by the heavy atom method with the 4176 independent and statistically significant structure factors refining to a value of R = 0.07. The diphosphonium ring is in the chair conformation with each phosphorus ion having an axial and equatorial phenyl ring attached. P-C and C-C bond lengths of 1.78 ± .03 Å and 1.53 ± .03 Å respectively agree well with the literature value for these distances.     

Synthesis and crystal structure of cyclopentadienyl(1,4-dimethyl-1,4-dibora-2,5-cyclohexadiene)cobalt

The synthesis of the organometallic derivative cyclopentadienyl(1,4-dimethyl-1,4-diboracyclohexa-2,5-diene)cobalt is described. This complex, [(CH₃BC₄H₄BCH₃)Co(η-C₅H₅)], forms red-oranged monoclinic crystals, space group P2₁/a with Z = 4 in a unit cell of dimensions a 11.362(7), b, 7.467(7), c 13.290(12) Å, β 103.76(6)°. The structure has been elucidated by heavy-atom methods from 1732 reflections (I > 2σ(I)) measured on a Syntex P2₁ four-circle diffractometer and refined to R = 0.055. In the coordination complex all six atoms of the cyclohexadiene ring are within bonding distance of the metal atom, but the two boron atoms bend away from the metal atom, and the ring elongates slightly in the B---B direction. As a standard of comparison the known geometry of the free ligand [1,4-difluoro-1,4-dibora-2,3,5,6-tetramethylcyclohexa-2,5-diene] is used. The terminal methyl groups on the boron atoms, by contrast, bend slightly back towards the metal atom. The cyclopentadienyl ring remains planar but is positionally disordered.     

The crystal and molecular structure of 2,5-dichloro-3-methoxypyrazine

A three-dimensional X-ray structure determination of 2,5-dichloro-3-methoxypyrazine has been completed with diffractometer data. The crystals are monoclinic, space group P2₁/_c, with lattice constants a = 4.059, b = 15.773, c = 11.123Å and β = 90.96° (Z = 4). The structure was solved by Sayre's equation and all hydrogen atoms were located by difference synthesis. Full-matrix least-squares refinement of all position parameters, hydrogen isotropic temperature factors, and anisotropic temperature factors for all other atoms converged at R = 5.7% for the 1397 reflections above background. Bond distances and angles are consistent with literature values.     

Synthesis and structure of 1,4-diaryl-7,7-dimethyl-1,2,3,4,5,6,7,8-octahydroquinoline-2,5-diones

Condensation of 5-arylidene-2,2-dimefhyl-1,3-dioxane-4,6-diones with 5,5-dimethyl-3-arylamino-2-cyclohexanones yields 1,4-diaryl-7,7-dimethyl-1,2,3,4,5,6,7,8-octahydroquinoline-2,5-diones. The compounds have been characterized from their IR, UV, and PMR spectra. It has been established that the N-phenyl ring, which projects from the plane of the octahydroquinolinedione ring, has a shielding effect on the magnetic field of the protons at the 7- and 8-positions of the ring in the molecules of the compounds synthesized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1227–1232, September, 1993.     

The crystal and molecular structure of 10,10-dimethyl-10-germa-9-thio-9,10-dihydroanthracene

The X-ray analysis of 10,10-dimethyl-10-germa-9-thio-9,10-dihydroantracene has been carried out. The crystals are orthorhombic: a 11.130(3), b 7.556(2), c 30.795(5) »; Z = 4; space group Pbca. The structure was solved by a combination of Patterson and Fourier methods and refined to R = 0.047 (R_w = 0.050, w = 1/a²(F₀)). The molecule is not planar and the dihedral angle formed by the two benzene rings is 143.6°. The central ring has the boat conformation. The ¹³C NMR chemical shifts associated with benzene carbon atoms correlate well with bond angles obtained by X-ray methods.     

ω, ω′-Dihetaryl-substituted 2,5-dimethyl-1,4-divinylbenzenes

A series of ω, ω′-dihetaryl-substituted 2,5-dimethyl-1,4-divinylbenzenes has been synthesized and these show an increased solubility when compared with analogs not containing methyl groups in the central benzene ring. The dependence of spectral parameters on the chemical structure has been analyzed. Institute of Monocrystals, Ukrainian Academy of Sciences, Kharkov 310001. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 688–691, May, 1999.     

Synthesis of benzoates of 1,4-bis(2,5-dimethyl-4-hydroxypiperidino)-2-butene and 1,4-bis-(2,5-dimethyl-4-hydroxypiperidino)-2-butyne

1,4-Bis(2,5-dimethyl-4-hydroxypiperidino)-2-butene and 1,4-bis(2,5-dimethyl-4-hydroxypiperidino)-2-butyne (II and III) were obtained by the action of 1,4-dibromo-2-butene and 1,4-dibromo-2-butyne on the form of 2,5-dimethyl-4-piperidol (I). The benzoates (IV and V) were obtained by acylation of II and III with benzoyl chloride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 352–353, March, 1971.     

The crystal molecular structure of cis-13,13-dimethyl-13-azoniabicyclo [10.1.0] tridecane iodide

The crystal and molecular structure of cis-13,13-dimethyl-13-azoniabicyclo[10.1.0]tridecane iodide has been determined by a three-dimensional, single-crystal, x-ray diffraction study. The compound crystallizes in the orthorhombic space group Pnam with cell dimensions a_Q = 21.36 ± .01, b_O = 9.07, c_O = 8.29 Å. The aziridine ring is fused to the cyclododecane ring with fusion angles of 123.5°. The molecule is bisected by a mirror plane with the cyclododecane portion distorted from its anticipated square conformation. Transannular hydrogen interactions are estimated on the basis of geometric considerations. A final value of R = 0.112 was obtained for the 557 non-equivalent reflections which were observed.     

Selenium heterocycles. XIX. Synthesis of selenophenes and triarylbenzenes from 2,5-diaryl-1,4-dithiin 1,1,4,4-tetroxides

Mixtures of 2,5-diaryl-1,4-dithiin 1,1,4,4-tctroxides and selenium were subjected to heat and afforded 2,5-diarylselenophenes. Pyrolysis of 2,5-diaryl-1,4-dithiin 1,1,4,4-tetroxides led to the formation of a mixture of 1,2,4- and 1,3,5-triarylbenzenes.     

1,1,4,4-Tetranitrobutane-2,3-diol and its derivatives. 3. Synthesis of 1,4-dichloro- and 1,4-dibromo-1,1,4,4-tetranitrobutane-2,3-diol dinitrates and their crystalline structure

1,4-Dichloro- (1) and 1,4-dibromo-1,1,4,4-tetranitrobutane-2,3-diol dinitrates (2) were synthesized by nitration of the corresponding diols with a mixture of trifluoroacetic anhydride and nitric acid. The x-ray diffraction investigations of 1 and 2 that have been carried out showed the influence of the intramolecular interactions of the nitro and nitrate groups on the packing of the molecules in the crystal.Institute of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 664–671, March, 1992.