An X-ray structural examination of an intermediate from the cleavage of a vic-diol by iodine(I) acetate

1980 ◽  
Vol 33 (3) ◽  
pp. 671 ◽  
Author(s):  
PG Beckingsale ◽  
JM Waters ◽  
TN Waters
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Direct Methods ◽  
Structural Examination ◽  
Space Group ◽  
X Ray

The crystal structure of a compound isolated after reaction of iodine(1) acetate with cis-cyclohexane-1,2-diol has been determined by direct methods. It is identified as 2,2'-(butane-1,4-diyl)bis(hexahydro-1,3-benzodioxole). Crystals are orthorhombic, a 8.625(2), b 7.589(1), c 26.187(5) Ǻ, space group Pbca, Z 4. Least- squares refinement brought R to 0.046.

Ring contraction of 4-substituted 2,6-dichlorophenols. The crystal structure of 2,2,4α,5α-Tetrachloro-1α,3α-dihydroxycyclopentane-1,4-carbolactone

1977 ◽  
Vol 30 (10) ◽  
pp. 2195 ◽  
Author(s):  
RM Christie ◽  
RW Rickards ◽  
KJ Schmalzl ◽  
D Taylor
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Direct Methods ◽  
Major Product ◽  
X Ray Diffraction ◽  
Ring Contraction ◽  
Full Matrix ◽  
Space Group ◽  
X Ray ◽  
Counter Data

Alkaline chlorination of the 4-alkyl-2,6-dichlorophenols (2b) and (2c) proceeds through ring contraction and halolactonization to form the 4α- alkyl-2,2,5α-trichloro-1α,3α-dihydroxycyclopentane-1,4-carbolactones (4b) and (4c). Under similar conditions, 2,4,6-trichlorophenol affords the analogous 2,2,4α,5α-tetrachloro-1α,3α-dihydroxycyclopentane-1,4- carbolactone (4a) in low yield, in addition to the Hantzsch acid (3a) as the major product. The acid (3a) upon further treatment undergoes chloro-lactonization to give the lactone (4a). The structures of the lactones (4b) and (4c) follow from spectroscopic comparison with (4a), the structure of which has been established by X-ray diffraction (C6H4Cl4O4 orthorhombic a 13.485(1), b 12.348(1), c 11.371(1) Ǻ, space group Pccn, Z 8, solved by direct methods and refined by block-diagonal and full-matrix least squares to R 0.031, Rw 0.043 for 1313 unique counter data with I/σ(I) ≥ 3.0).

Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe, IX [1]. Die Molekül- und Kristallstruktur von Tri-tert-butylcyclotriphosphanpentacarbonyl- chrom(O), [(t-BuP)3Cr(CO)5] / Structural Chemistry of Phosphorus-Containing Chains and Rings, IX [1]. The Molecular and Crystal Structure of Tri-tert-butylcydotriphosphane-pentacarbonyl-chromium (0), [(t-BuP)3Cr(CO)5]

1984 ◽  
Vol 39 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Karl-Friedrich Tebbe ◽  
Magda Fehér
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Direct Methods ◽  
Membered Ring ◽  
Free Molecule ◽  
Donor Ligand ◽  
Space Group ◽  
X Ray ◽  
Phosphorus Containing

The structure of [(t-BuP)3Cr(CO)5], C17CrH27O5P3, has been determined by single crystal X-ray techniques, solved by ‘direct methods', and refined to R = 0.048, wR = 0.050 for 3657 reflections by blocked least squares. The compound crystallizes in the space group P 21/c with a = 1664.9 pm, b = 916.5 pm , c = 3089.8 pm, β= 91.45° and Z = 8 formula units. The structure consists of two crystallographically independent but structurally nearly identical mononuclear [(t-BuP)3Cr(CO)5] complexes with the three-membered ring (t-BuP)3 as an unidentate σ-donor ligand. Compared to the free molecule (t-BuP)3 the cyclophosphane ligand is slightly distorted on account of its coordination to the Cr(CO)5-group.

The crystal structure and stereochemistry of 2-acetyl-3,5,6-trihydroxy-5,6-dimethyl-2-cyclohexenones

1988 ◽  
Vol 66 (2) ◽  
pp. 246-248 ◽  
Author(s):  
Giorgio Adembri ◽  
Mirella Scotton ◽  
Alessandro Sega
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Structure Analysis ◽  
Direct Methods ◽  
Crystal Structure Analysis ◽  
Full Matrix ◽  
Space Group ◽  
X Ray ◽  
Bicyclic System ◽  
Centrosymmetric Dimers

The stereochemistry of 3a, one of the 2-acetyl-3,5,6-trihydroxy-5,6-dimethylcyclohexenones, obtained by rearrangement of 2,3-diacetyl-4-hydroxy-4-methylcyclopentenone, 2a, under basic conditions, was determined by an X-ray crystal structure analysis. An ORTEP plot shows the configuration of (5RS,6RS)-2-acetyl-3,5,6-trihydroxy-5,6-dimethylcyclohexenone and the presence of a conjugated chelated system involving the H-bonding between O(3)… H(31) and H(31)… O(2).Crystals of 3a are triclinic, a = 10.979(4), b = 7.766(3), c = 6.382(3) Å, α = 86.23(2), β = 72.86(1), γ = 88.23(2)°, Z = 2, space group [Formula: see text]. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.036 and Rw = 0.039 for 1324 reflections with I > 3σ(I).The structure of 3a consists of centrosymmetric dimers which contain a nearly planar bicyclic system of a cyclohexenone moiety and a chelated system (Scheme 2).The pathway of the reaction allows one to put forward some hypothesis on the stereochemistry of some analogues of the cyclohexenones 3a and 3b.Faisant appel à la diffraction des rayons-X, on a déterminé la stéréochimie du composé 3a, une des acétyl-2 trihydroxy-3,5,6 diméthyl-5,6 cyclohexénones obtenues par une transposition de la diacétyl-2,3 hydroxy-4 méthyl-4 cyclopenténone, 2a, en milieu alcalin. Une courbe ORTEP démontre que la configuration est (5RS,6RS) pour l'acétyl-2 trihydroxy-3,5,6 diméthyl-5,6 cyclohexénone et qu'il existe un système de chélation conjugué impliquant des liaisons hydrogènes entre O(3)… H(31) et H(31)… O(2).

Porphyrins incorporating heterocyclic N-oxides: (oxidopyridyl)porphyrins, porphyrin-N-oxides, and a tirapazamine-porphyrin conjugate

1999 ◽  
Vol 77 (2) ◽  
pp. 182-198 ◽  
Author(s):  
Jeffrey J Posakony ◽  
Russell C Pratt ◽  
Steven J Rettig ◽  
Brian R James ◽  
Kirsten A Skov
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Key Words ◽  
Direct Methods ◽  
Spectroscopic Methods ◽  
Full Matrix ◽  
Space Group ◽  
X Ray

Porphyrins containing one to four 4-pyridyl groups as meso-substituents were synthesized via a mixed aldehyde condensation, and then "N-oxidized" with m-chloroperbenzoic acid to produce five novel (oxidopyridyl) porphyrins and seven porphyrin-N-oxides, which were characterized by analysis and spectroscopic methods, especially NMR; an X-ray crystal structure of 5-(1-oxido-4-pyridyl)-10,15,20-triphenylporphyrin was also obtained. Crystals of (oxidopyridyl)triphenylporphyrin are tetragonal, a = b = 15.174(1), c = 13.709(1) Å, Z = 4, space group I2d. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.031 (Rw = 0.026) for 685 reflections with I [Formula: see text] 3σ(I). Sulfonation of two of the (oxidopyridyl)porphyrins was achieved readily with no loss of oxygen from the oxidopyridyl groups. Tirapazamine (3-amino-1,2,4-benzotriazine-1,4-di-N-oxide) was treated with triphosgene to yield the previously reported 2H-[1,2,4]oxadiazolo[3,2-c][1,2,4]benzotriazin-2-one-5-oxide (1); this reacts like an isocyanate and with 5-(4-aminophenyl)-10,15,20-triphenylporphyrin yields a tirapazamine-porphyrin conjugate (2).Key words: porphyrin-N-oxides, (oxidopyridyl)porphyrins, tirapazamine.

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

Structure of 3α,4α:5β,6β-Diepoxyandrostan-17-one

1983 ◽  
Vol 36 (11) ◽  
pp. 2333 ◽  
Author(s):  
B Kamenar ◽  
RA Pauptit ◽  
JM Waters
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray

The X-ray crystal structure of 3α,4α:5β,6β-diepoxyandrostan-17-one has been determined. Crystals of the title compound (C19H26O3)are monoclinic, space group P21, with a 9.208(2), b 9.620(4), c 9.312(3) �, β 99.14(2)�, V 814.5 Ǻ3 and Z 2. The structure was solved by direct methods and refined to R 0.039 for 887 observed reflexions. The 3α,4α:5β,6β configuration of the epoxide rings confirms the assignment based on proton n.m.r. studies.

The crystal structure of dibutyl-bis(pentamethylenedithiocarbamato)tin(IV)

1986 ◽  
Vol 51 (11) ◽  
pp. 2521-2527 ◽  
Author(s):  
Jan Lokaj ◽  
Eleonóra Kellö ◽  
Viktor Kettmann ◽  
Viktor Vrábel ◽  
Vladimír Rattay
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Least Squares ◽  
Coordination Polyhedron ◽  
Crystal And Molecular Structure ◽  
Distorted Octahedron ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray

The crystal and molecular structure of SnBu2(pmdtc)2 has been solved by X-ray diffraction methods and refined by a block-diagonal least-squares procedure to R = 0.083 for 895 observed reflections. Monoclinic, space group C2, a = 19.893(6), b = 7.773(8), c = 12.947(8) . 10-10 m, β = 129.07(5)°, Z = 2, C20H38N2S4Sn. Measured and calculated densities are Dm = 1.38(2), Dc = 1.36 Mg m-3. Sn atom, placed on the twofold axes, is coordinated with four S atoms in the distances Sn-S 2.966(6) and 2.476(3) . 10-10 m. Coordination polyhedron is a strongly distorted octahedron. Ligand S2CN is planar.

The crystal structure of kogarkoite, Na3SO4F

1980 ◽  
Vol 43 (330) ◽  
pp. 753-759 ◽  
Author(s):  
L. Fanfani ◽  
G. Giuseppetti ◽  
C. Tadini ◽  
P. F. Zanazzi
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Least Squares Method ◽  
Thermal Parameters ◽  
Cell Content ◽  
Space Group ◽  
X Ray ◽  
Structural Relationships ◽  
Automatic Diffractometer ◽  
Monoclinic Cell

SummaryThe crystal structure of synthetic kogarkoite has been determined from X-ray data collected on an automatic diffractometer. The refinement was performed by a least-squares method employing anisotropic thermal parameters. The 3157 reflections with I > 3σ(I) converged to a conventional R value of 0.033. The cell content is 12 Na3SO4F, the space-group P21/m, a = 18.074, b = 6.958, c = 11.443 Å, β = 107.71°.Kogarkoite presents a marked trigonal subcell with c′ corresponding to [102] of the monoclinic cell. The tridimensional framework can be considered built up by nine differently stacked layers of Na atoms approximately perpendicular to the c′ axis (five sheets are present in galeite, six in sulphohalite, and seven in schairerite). The very close structural relationships between these minerals are discussed.

Oxofluoro-oxalato-vanadate des vierwertigen Vanadins: Schwingungsspektrum und Struktur von Na3[VOF(C2O4)2] • 6 H2O.

1976 ◽  
Vol 31 (5) ◽  
pp. 537-540 ◽  
Author(s):  
Helmut Rieskamp ◽  
Rainer Mattes
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Fluorine Atom ◽  
Direct Methods ◽  
Terminal Oxygen Atom ◽  
Triclinic Space Group ◽  
Trans Effect ◽  
Space Group ◽  
X Ray ◽  
In Cis

The Na and NH4 salts of the [VOF(C2O4)2]3--ion have been prepared. The crystal structure of the former has been determined from X-ray diffractometer data. The crystals are triclinic, space group P with Z = 2. The structure was solved by `direct methods' and refined to R 0.050 for 1749 reflections. In the anion, vanadium(IV) is octahedrally coordinated by a terminal oxygen atom, a fluorine atom in cis-position to the former, and two bidentate oxalate ligands. The terminal V—O-bond exhibits a strong ‘trans’ effect.

Insecticides. XI. Crystal structure of endosulfan, β-6,7,8,9,10,10-Hexachloro-1,5,5a,6,9,9a-hexahydro-endo-6,9-methano-2,4,3-benzodioxathiepin 3-Oxide

1977 ◽  
Vol 30 (4) ◽  
pp. 911 ◽  
Author(s):  
G Smith ◽  
CHL Kennard ◽  
KG Shields
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Direct Methods ◽  
Space Group ◽  
A Cell

The crystal structure of hexagonal β-endosulfan (β1) was determined by direct methods. On a four-circle diffractometer, 2350 reflections were collected. The crystals were hexagonal, (P63/m), with Z = 6, in a cell of dimensions a = 1492.0(2), c = 1150.6(2) pm. The structure was refined by least squares to R 0.068 from 573 unique reflections having F > 2.5σ(F). The methylene sulphite ring showed an ?endo-endo-endo? configuration with respect to its attachment to the methano- bridged hexachlorocyclohexane and exo to the oxide portion of the sulphite group. Space group requirements for P63/m resulted in the molecules lying along the mirror planes at Z = 1/4 and 3/4.

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