The Structure of Thiobinupharidine

1973 ◽  
Vol 51 (17) ◽  
pp. 2810-2820 ◽  
Author(s):  
J. T. Wróbel ◽  
B. Bobeszko ◽  
T. I. Martin ◽  
D. B. MacLean ◽  
N. Krishnamachari ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Least Squares ◽  
Absolute Configuration ◽  
Spectroscopic Properties ◽  
Relative Configuration ◽  
Full Matrix ◽  
Space Group ◽  
R Value ◽  
Least Squares Techniques

The spectroscopic properties of thiobinupharidine and its isomer, neothiobinupharidine, of established structure, have been examined and compared. From this study it was possible to deduce the structure and relative configuration of the alkaloid. The structure has been firmly established and the absolute configuration determined by the study of the crystal structure of thiobinupharidine dihydrobromide dihydrate, C30H42O2N2S•2HBr•2H2O. The crystals are orthorhombic with space group C2221, a = 25.128(6), b = 9.869(2), c = 26.380(6) Å, and Z = 8. The structure was refined, using full-matrix least-squares techniques with 1934 reflections, to a final R value of 0.097. The thiobinupharidine moiety hydrogen bonds to one of two types of H2O–Br–H2O spiral chains in the structure. The tetrahydrothiophene ring is distorted from planarity, and this together with the nonequivalence of the S and C atoms in the ring causes the molecule to deviate from C2 symmetry

The Crystal Structure of Dimedone

1975 ◽  
Vol 53 (7) ◽  
pp. 1046-1050 ◽  
Author(s):  
Ishwar Singh ◽  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Hydrogen Bonds ◽  
Least Squares ◽  
Direct Methods ◽  
Monoclinic Symmetry ◽  
Enolic Form ◽  
Full Matrix ◽  
Space Group ◽  
Least Squares Techniques

Dimedone, C8H12O2, crystallizes with monoclinic symmetry, a = 10.079(7), b = 6.835(3), c = 12.438(4) Å, β = 110.24(5)°, space group P21/n and Z = 4. The structure of this compound was solved by direct methods and refined by full-matrix least-squares techniques using 1205 unique reflections to a final R of 0.047. In the solid state it exists in the enolic form and these molecules pack in the crystal in systems of infinite chains linked together by hydrogen bonds in the y direction. These results are virtually the same as recently reported by Semmingsen.

The crystal structure of ferrinatrite, Na3(H2O)3[Fe(SO4)3] and its relationship to Maus's salt, (H3O)2K2{K0.5(H2O)0.5}6[Fe3O(H2O)3(SO46](OH)2

1977 ◽  
Vol 41 (319) ◽  
pp. 375-383 ◽  
Author(s):  
F. Scordari
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Least Squares ◽  
Three Dimensional ◽  
Iron Ions ◽  
Space Group ◽  
R Value ◽  
Oxygen Atoms

SummaryFerrinatrite crystallizes in space group P, with a = 15·566(5), c = 8·69(1) Å, and Z = 6. The crystal structure was solved by three-dimensional Patterson and Fourier syntheses, and refined by least squares employing 2378 independent reflexions to a final R value of 0·068. The iron ions occupy special positions and are surrounded octahedrally by oxygen atoms. Fe3+O6 octahedra and SO4, tetrahedra are linked together to form infinite chains of Fe-O-S linkages in the [0001] direction. These chains are linked to each other by [NaO5(H2O)2] polyhedra and probably by hydrogen bonds. The topology of the arrangement is the same as that of the hypothetical P312 structure proposed by Moore and Araki (1974).

Refinement of the structure of Mg2As2O7

1970 ◽  
Vol 48 (6) ◽  
pp. 890-894 ◽  
Author(s):  
C. Calvo ◽  
K. Neelakantan
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Unit Cell ◽  
Full Matrix ◽  
Space Group ◽  
Cell Dimensions ◽  
Central Oxygen ◽  
R Value ◽  
Unit Cell Dimensions

The crystal structure of Mg2As2O7 has been refined by full matrix least squares procedures using 587 observed reflections. The structure of Mg2As2O7 is of the thortveitite type, as reported by Łukaszewicz, with space group C2/m and unit cell dimensions a = 6.567(2) Å, b = 8.524(4) Å, c = 4.739(1) Å, β = 103.8(1)°, and Z = 2. The As—O—As group in the anion appears to be linear but the central oxygen atom undergoes considerable disorder in the plane perpendicular to this group. The AsO bond distances uncorrected for thermal motion are 1.67 Å for the As—O(—As) bond and 1.66 and 1.65 Å for the terminal As—O bonds. The final R value obtained is 0.088.

Crystal and molecular structure of L-prolinatodiphenylboron

1977 ◽  
Vol 55 (6) ◽  
pp. 958-965 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Conformational Disorder ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths

Crystals of L-prolinatodiphenylboron are monoclinic, a = 5.9427(5), b = 14.4633(7), c = 8.9654(4) Å, β = 98.423(8)°, Z = 2, space group P21. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.037 and Rw of 0.053 for 1477 reflections with I ≥ 3σ(I). The proline ring exhibits conformational disorder. The crystal structure consists of discrete molecules linked by N—H … O hydrogen bonds (N … O = 2.893(3) Å) along the short a axis. Intramolecular N—B coordination occurs to form a system of two fused five-membered rings. Bond lengths (corrected for libration) are: N—B, 1.630(3), O—B, 1.529(3), O—C, 1.219(3) and 1.300(3), N—C, 1.506(3) and 1.507(3), C(sp3)–C(sp3), 1.525(4), C(sp2)—C(sp3), 1.517(3), and mean C—C(phenyl), 1.394 Å.

The crystal structure of p-diethylaminobenzenediazonium hexafluorophosphate

1985 ◽  
Vol 63 (2) ◽  
pp. 332-335 ◽  
Author(s):  
Richard G. Ball ◽  
Richard MacLeod Elofson
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Triple Bond ◽  
Direct Methods ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths ◽  
The Mean ◽  
Least Squares Techniques ◽  
Diazo Group

p-Diethylaminobenzenediazonium hexafluorophosphate, C10H14N3+•PF6−, crystallized in space group [Formula: see text] with a = 12.105(4), b = 12.340(5), c = 10.439(4) Å, α = 96.53(3), β = 104.11(3), γ = 64.44(3)°, and Z = 4. The structure was solved using direct methods and refined with full-matrix least-squares techniques on F, to a final R of 0.054 for 1917 reflections with F2 > 3σ(F2). The mean bond lengths for the diazo group are: N—N 1.096(6); C—N 1.357(7) Å. The geometry of the molecule is discussed in terms of the possible resonance forms and it is shown to be consistent with a form in which the N—N triple bond is essentially intact and the aminobenzene moiety has "quinoidal" character.

Refinement of the Crystal Structure of the Low-quartz Modification of Ferric Phosphate

1975 ◽  
Vol 53 (14) ◽  
pp. 2064-2067 ◽  
Author(s):  
Hok Nam Ng ◽  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Room Temperature ◽  
Unit Cell ◽  
Full Matrix ◽  
Space Group ◽  
Ferric Phosphate ◽  
R Value

The structure of ferric phosphate at room temperature was refined on a Dauphiné-twinned crystal using full-matrix least-squares methods. The final R value was 0.078 for 487 symmetry-independent reflections whose intensities were corrected for twinning. The structure was found to be isotypic with AlPO4 (berlinite) with the space group P3121 and four formula units in a unit cell defined by a = 5.036(2) and c = 11.255(4) Å. The structure is also closely related to that of α-quartz with a nearly doubled c-axis because of the ordering of Fe and P atoms. The PO4 tetrahedron is almost regular with a mean P—O distance of 1.526 Å. The Fe3+ ion is tetrahedrally coordinated with an average Fe—O distance of 1.853 Å.

Crystal Structure of Synthetic Mg-Whitlockite, Ca18Mg2H2(PO4)14

1974 ◽  
Vol 52 (7) ◽  
pp. 1155-1164 ◽  
Author(s):  
Ramanathan Gopal ◽  
Crispin Calvo ◽  
Jun Ito ◽  
W. K. Sabine
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Formula Unit ◽  
Full Matrix ◽  
Space Group ◽  
R Value ◽  
Unit Density ◽  
A Chain ◽  
Automatic Diffractometer

Crystals of synthetic Mg-whitlockite, Ca18Mg2H2(PO4)14, have been grown by hydrothermal techniques and their structure refined by full-matrix least-squares methods, using 1626 unique reflections measured with a Syntex [Formula: see text] automatic diffractometer, to a final R value of 0.046. The crystals have space group R3c with ZR = 1, a = 13.765(8) Å and α = 44.25(5)° with the equivalent hexagonal parameters a = 10.350(5), c = 37.085(12) Å and ZH = 3. The structure, although similar to that of βCa3(PO4)2, differs significantly. The structure contains interconnected infinite chains of polyhedra paralleling the hexagonal c axis with links in the chains consisting of three CaO8 polyhedra separated by two PO4 tetrahedra. Six of these chains surround a chain of MgO6 octahedra and PO4H groups which lie on the three-fold axes. These chains however contain only half the formula unit density of the calcium containing ones and a proton, presumably disordered, is attached to the oxygen atom on the triad axes.

Crystal and Molecular Structure of B-Phenyl-diptychboroxazolidine,

1975 ◽  
Vol 53 (10) ◽  
pp. 1393-1401 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Thermal Motion ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths

Crystals of B-phenyl-dictychboroxazolidine are monoclinic, a = 8.4977(4), b = 9.0617(5), c = 7.0105(3) Å, β = 111.627(3)°, Z = 2, space group P21. The structure was solved by direct methods and was refined by full-matrix least squares procedures to a final R of 0.040 for 967 reflections with I ≥ 3σ(I). The bond lengths involving nonhydrogen atoms have been corrected for thermal motion. Bond lengths are: B—O, 1.460(3) and 1.474(3), B—N, 1.666(3), B—C, 1.613(3), C—O, 1.411(3) and 1.419(3), C—N, 1.485(3) and 1.486(3), C(sp3)—C(sp3), 1.514(4) and 1.524(4), C—C(ar), 1.384–1.400(4–6), mean C—H, 0.98(4), and N—H, 0.87(5) Å. The crystal structure consists of discrete molecules of B-phenyl-diptychboroxazolidine each linked to two others by N—H … O hydrogen bonds (O … N = 2.914(3) Å) to form continuous spirals along b.

Crystal Structure of Tetraethylammonium Bromopentacarbonyltungstate(0)

1995 ◽  
Vol 48 (5) ◽  
pp. 1045 ◽  
Author(s):  
T Whyte ◽  
GA Williams
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
Space Group ◽  
X Ray ◽  
Bond Lengths ◽  
R Value

The crystal structure of tetraethylammonium bromopentacarbonyltungstate (0), [NEt4] [W(CO)5Br], has been determined by single-crystal X-ray diffraction methods at 22�1°C. Crystals are tetragonal, space group P4/n, with a 9.206(2), c 10.484(2) Ǻ, and Z 2. Full-matrix least-squares refinement gave a final R value of 0.034 for 820 independent reflections. The [W(CO)5Br]- anion possesses exact C4v symmetry, with bond lengths W-Br 2.736(1), W-COtrans 1.93(1) and W-COcis 2.034(6) Ǻ.

The Alkaloids of Margaritaria indica (Euphorbiaceae). The Crystal Structure and Absolute Configuration of the Hydrobromide of (+)-15α-Methoxy-14,15-dihydrophyllochrysine

1990 ◽  
Vol 43 (2) ◽  
pp. 439 ◽  
Author(s):  
D Arbain ◽  
LT Byrne ◽  
JR Cannon ◽  
LM Engelhardt ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Absolute Configuration ◽  
Spectroscopic Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Least Squares Techniques

(-)-Phyllochrysine (1), (-)-securinine (2) and a new alkaloid (+)-15α-methoxy-14,15-dihydrophyllochrysine (3) have been isolated from both the bark and roots of Margaritaria indica ( Dalz .) G. L. Webster. The structure and absolute configuration of (3) follow from its spectroscopic properties and its synthesis from (-)- phyllochrysine (1) as well as from the crystal structure of its hydrobromide, obtained by X-ray diffraction. Diffractometer data at 295 K were refined by least-squares techniques to a residual of 0.053 (991 'observed' reflections). Crystals of 15α-methoxy-14,15-dihydrophyllochrysine hydrobromide are orthorhombic, P212121, a 14.324(3), b 14.194(3), c 7.240(2)Ǻ, Z 4.

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