1H and 13C NMR study of tetrahydro-1,4-benzothiazepine conformationsElectronic supplementary information (ESI) available: crystal data, structure refinement and a perspective view of the X-ray crystal structure of 1. See http://www.rsc.org/suppdata/p2/b2/b205768a/

Author(s):  
Alan R. Katritzky ◽  
Novruz G. Akhmedov ◽  
Ion Ghiviriga ◽  
Peter J. Steel
1998 ◽  
Vol 54 (6) ◽  
pp. 722-731 ◽  
Author(s):  
F. Reinauer ◽  
R. Glaum

The crystal structure of pentatitanium tetraoxide tetrakis(phosphate), Ti5O4(PO4)4, has been determined and refined from X-ray diffraction single-crystal data [P212121 (No. 19), Z = 4, a = 12.8417 (12), b = 14.4195 (13), c = 7.4622 (9) Å (from Guinier photographs); conventional residual R 1 = 0.042 for 2556 Fo > 4σ(Fo ), R 1 = 0.057 for all 3276 independent reflections; 282 parameters; 29 atoms in the asymmetric unit of the ideal structure]. The structure is closely related to those of β-Fe2O(PO4)-type phosphates and synthetic lipscombite, Fe3(PO4)4(OH). While these consist of infinite chains of face-sharing MO6 octahedra, in pentatitanium tetraoxide tetrakis(phosphate) only five-eighths of the octahedral voids are occupied according to □3Ti5O4(PO4)4. Four of the five independent Ti4+O6 show high radial distortion [1.72 ≤ d(Ti−O) ≤ 2.39 Å] and a typical 1 + 4 + 1 distance distribution. The fifth Ti4+O6 is an almost regular octahedron [1.91 ≤ d(Ti−O) ≤ 1.98 Å]. Partial disorder of Ti4+ over the available octahedral voids is revealed by the X-ray structure refinement. High-resolution transmission electron microscopy (HRTEM) investigations confirm this result.


Synthesis ◽  
2020 ◽  
Vol 53 (02) ◽  
pp. 365-370
Author(s):  
Lucas Pizzuti ◽  
Izamara Casadia ◽  
Thalita O. Daher ◽  
Sidnei Moura ◽  
Davi F. Back ◽  
...  

A convenient domino route for the synthesis of novel 1,3-dihydrofuro[3,4-c]pyridines from pyridoxal and alkyl, aryl or heteroaryl ketones under basic conditions is reported. A series of nine derivatives is obtained in 53–90% yields after stirring reactants for 48 hours at room temperature. Most products are easily isolated by filtration followed by recrystallization from ethanol. All products were fully characterized by FTIR, HRMS, and 1H and 13C NMR spectroscopy. The X-ray crystal structure of a representative example of the 1,3-dihydrofuro[3,4-c]pyridine series is also presented.


1979 ◽  
Vol 32 (6) ◽  
pp. 1199 ◽  
Author(s):  
W Choong ◽  
NC Stephenson ◽  
MA Ali ◽  
MA Malik ◽  
DJ Phillips

The crystal structure of Ni(dapsm)(NCS)2 [dapsm is 2,6-bis(1-methyl-4-methylthio-5-thia-2,3-diazahexa-1,3-dienyl)pyridinel has been determined from three-dimensional single-crystal diffractometer X-ray data. Structure refinement was carried out by least-squares methods to a final R value of 0.059. The ligand dapsm is a potential N3S2 pentadentate, but it coordinates as a tetradentate, giving a planar N3S donor grouping. Rotation occurs about an N-N bond in dapsm, moving a potential donor sulfur atom away from the nickel(II) ion. The pyridine ring of the ligand, and the N3S donor grouping, are approximately coplanar. Two thiocyanate groups are coordinated to the nickel, giving a distorted octahedral structure. The structure and electronic spectrum of Ni(dapsm)- (NCS)2 are compared with those for seven-coordinate complexes with the related N3O2 ligand, 2,6-diacetylpyridine bissemicarbazone.


1990 ◽  
Vol 5 (7) ◽  
pp. 1538-1543 ◽  
Author(s):  
H. Toraya ◽  
N. Masciocchi ◽  
W. Parrish

The crystal structure of Na2Al2Ti6O16 was refined by the Rietveld method using synchrotron radiation and conventional x-ray powder data, and the agreement factors were Rp = 3.35%, Rwp = 4.30%, and RBragg = 6.39% for synchrotron data. The formula based on the chemical analysis and 16 O atoms is Na1.97Al1.82Ti6.15O16. The crystal data are monoclinic, C2/m, a = 12.1239(3) Å, b = 3.7749(1) Å, c = 6.4180(2) Å, β = 107.59(1)°, V = 280.00(4) Å3, Z = 1, and Dx = 3.82 g cm−3. The site occupancy refinement showed a partial ordering of Al3+ and Ti4+ ions in the two-crystallographically independent octahedral sites.


Polyhedron ◽  
1991 ◽  
Vol 10 (8) ◽  
pp. 841-849 ◽  
Author(s):  
John W. Connolly ◽  
Michael J. Hatlee ◽  
Alan H. Cowley ◽  
Paul R. Sharp

2014 ◽  
Vol 78 (5) ◽  
pp. 1249-1264 ◽  
Author(s):  
J. Plášil ◽  
M. Dušek ◽  
J. Čejka ◽  
J. Sejkora

AbstractThe crystal structure of rabejacite from Jáchymov, ideally Ca2[(UO2)4O4(SO4)2](H2O)8, was solved by charge flipping from single-crystal data and refined to R1 = 11.94% for 1422 unique observed reflections [I > 3σ(I)]. According to single-crystal X-ray data, rabejacite is triclinic, space group P1̄ , with a = 8.7434(11), b = 8.309(3), c = 8.8693(10) Å , a = 77.86(2), b = 104.635(11), g = 82.935(18)°, V = 598.8(3) A˚ 3 and Z = 1, with Dcalc = 4.325 g cm–3. The structure refinement proved that rabejacite is related to the zippeite group of minerals, as it is based upon the structural sheets of the zippeite topology of composition [(UO2)4O4(SO4)2]4–. Located in the interlayer between the sheets, which are stacked perpendicular to [010], are Ca2+ cations and H2O groups. Ca2+ ions are [7]-coordinated, by three uranyl O atoms from adjacent sheets and four H2O groups. An additional H2O group, which is not bonded directly to any cation, is located in the interlayer. Along with rabejacite, its Cu-rich variety was found in the specimens examined and characterized structurally. Its crystal structure (R1 = 10.15% for 1049 reflections with I > 3s(I)) is practically the same as that of rabejacite, but there is an additional Cu2+ site located in between pairs of Ca polyhedra. The structural formula is (Ca1.56Cu0.40)Σ1.90[(UO2)4O4(SO4)2](H2O)8, Z = 1. Its existence suggests a greater diversity in zippeite crystal chemistry than was thought previously and also the possibility of a new Cu2+-dominant zippeite mineral besides pseudojohannite.


1994 ◽  
Vol 72 (8) ◽  
pp. 1764-1768 ◽  
Author(s):  
G. W. Buchanan ◽  
A. B. Driega ◽  
A. Moghimi ◽  
C. Bensimon

The X-ray crystal structure of the title material has been determined and the results are compared to previous findings for benzo-9-crown-3 itself. The 13C NMR spectrum in solution has been unambiguously assigned using COSY and HETCOR methods. The solid phase 13C spectrum has been obtained and the 7, 10-d4 derivative has been examined to aid in spectral assignments.


1999 ◽  
Vol 32 (3) ◽  
pp. 443-462 ◽  
Author(s):  
J. Blazevic Šafarik ◽  
G. Karminski-zamola ◽  
Z. Marinic ◽  
B. Klaic ◽  
D. Mrvoš-sermek

1983 ◽  
Vol 244 (2) ◽  
pp. C27-C30 ◽  
Author(s):  
Gianfranco Ciani ◽  
Giuseppe D'Alfonso ◽  
Pierfrancesco Romiti ◽  
Angelo Sironi ◽  
Maria Freni

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