(IUCr) Absolute structure

Acta Cryst. (2012). C68, e13-e14
doi: 10.1107/S0108270112044757

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Virtual issue on absolute structure

H. D. Flack

Editorial

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Analysing Friedel averages and differences

S. Parsons, P. Pattison and H. D. Flack

The use of Friedel averages and differences is described for the following operations: determining whether a crystal is centrosymmetric or not, determining the point group of a crystal and validating intensity data after structure solution.

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Applications of leverage analysis in structure refinement

S. Parsons, T. Wagner, O. Presly, P. A. Wood and R. I. Cooper

Leverage analysis can be used to investigate the importance of weak data and the effectiveness of restraints. It can also improve the precision of estimates of selected parameters: the standard uncertainty of the Flack parameter can be reduced to 0.1 or below even for light-atom crystal structures.

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Practical applications of averages and differences of Friedel opposites

H. D. Flack, M. Sadki, A. L. Thompson and D. J. Watkin

The practical use of Friedel-difference intensities for space-group determination, least-squares refinement and structure validation is described.

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The mixed diol–dithiol 2,2-bis(sulfanylmethyl)propane-1,3-diol: characterization of key intermediates on a new synthetic pathway

T. R. Simmons, C. J. Pickett and J. A. Wright

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Planarity of heteroaryldithiocarbazic acid derivatives showing tuberculostatic activity. II. Crystal structures of 3-[amino(pyrazin-2-yl)methylidene]-2-methylcarbazic acid esters

A. Olczak, M. Szczesio, J. Gołka, C. Orlewska, K. Gobis, H. Foks and M. L. Główka

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Six two- and three-component ammonium carboxylate salt structures with a ladder-type hydrogen-bonding motif, three incorporating neutral carboxylic acid molecules

A. Lemmerer

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Racemic (1,4-dioxan-2-yl)diphenylmethanol

T. Hsiao, R. M. Buchanan and M. S. Mashuta

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Bis(4-methylbenzylammonium) tetrachloridozincate: a new noncentrosymmetric structure characterized by ¹³C CP–MAS NMR spectroscopy

R. Kefi, E. Jeanneau, F. Lefebvre and C. Ben Nasr

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Pseudopolymorphs of 2,6-diaminopyrimidin-4-one and 2-amino-6-methylpyrimidin-4-one: one or two tautomers present in the same crystal

V. Gerhardt, M. Tutughamiarso and M. Bolte

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On the symmetry of wulfenite (Pb[MoO₄]) from Mežica (Slovenia)

I. Cora, M. Czugler, I. Dódony and A. Rečnik

The structure of the unusual `hemimorphic' wulfenite crystals from the Mežica mine was refined in the space group I $\overline{4}$ as an inversion twin.

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Poly[aqua[μ₂-1,4-bis(imidazol-1-ylmethyl)benzene-κ²N³:N^3′](μ₂-5-hydroxybenzene-1,3-dicarboxylato-κ⁴O¹,O^1′:O³,O^3′)cadmium(II)], a twofold interpenetrated CdSO₄-like metal–organic polymer

S. Zhou, C.-B. Li, Q.-W. Wang and S. W. Ng

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Two hydration products of 3,4,5,6-tetrachloro-N-(methyl-2-pyridyl)phthalmic acids

P. G. Waddell, J. O. S. Hulse and J. M. Cole

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Extensive hydrogen and halogen bonding, and absence of intramolecular hydrogen bonding between alcohol and nitro groups in a series of endo-nitronorbornanol compounds

A. Lemmerer and J. P. Michael

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Two W/Cu/S clusters: tetraethylammonium bromidodi-μ₂-sulfido-sulfido[tris(3,5-dimethylpyrazol-1-yl)borato]copper(I)tungsten(VI) and tetraethylammonium dibromido-μ₃-sulfido-di-μ₂-sulfido-[tris(3,5-dimethylpyrazol-1-yl)borato]dicopper(I)tungsten(VI)

Z. Wei and X. You

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A tetragonal form of dysprosium orthomolybdate at room temperature

S. Dorzhieva, I. Chumak, A. Sarapulova, D. Mikhailova, J. Bazarova and H. Ehrenberg

The single crystals of the tetragonal modification of dysprosium orthomolybdate obtained in the present work are stable at room temperature. The crystal structure is formed by corner-sharing MoO₄ tetrahedra and Dy polyhedra coordinated by seven O atoms.

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(η⁵-Cyclopentadienyl)(η⁶-phenoxathiin 10,10-dioxide)iron(II) hexafluoridophosphate and phenoxathiin 10,10-dioxide

A. D. Hendsbee, J. D. Masuda and A. Piórko

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A square two-dimensional polymer of cobalt citrate cubanes

L. R. Falvello, E. Forcén-Vázquez, I. Mayoral, M. Tomás and F. Palacio

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Comparison of racemic epi-inosose and (−)-epi-inosose

S. Krishnaswamy, M. T. Patil and M. S. Shashidhar

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Cocrystals of 6-propyl-2-thiouracil: N—H⋯O versus N—H⋯S hydrogen bonds

M. Tutughamiarso and E. Egert

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Polymorphs of anhydrous theophylline: stable form IV consists of dimer pairs and metastable form I consists of hydrogen-bonded chains

D. Khamar, R. G. Pritchard, I. J. Bradshaw, G. A. Hutcheon and L. Seton

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2,5-Diaryl-1,3,4-selenadiazoles prepared from Woollins' reagent

D. B. Cordes, G. Hua, A. M. Z. Slawin and J. D. Woollins

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2-Ammonio-5-chloro-4-methylbenzenesulfonate, its 1-methyl-2-pyrrolidone and dimethyl sulfoxide monosolvates and a corrected structure of 2,2′-(1,4-phenylene)di(4,5-dihydroimidazolium) bis(4-aminobenzenesulfonate) dihydrate

S. L. Bekö, J. W. Bats and M. U. Schmidt

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Mixed crystals of 2-carbamoylguanidinium with hydrogen fluorophosphonate and hydrogen phosphite in the ratios 1:0, 0.76 (2):0.24 (2) and 0.115 (7):0.885 (7)

J. Fábry, M. Fridrichová, M. Dušek, K. Fejfarová and R. Krupková

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Trimethylurea

C. Döring, C. Taouss and P. G. Jones

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C—H⋯X (X = O, N or π) interactions in benzyl carbamate

I. Mata, E. Molins, M. Amat, N. Llor and B. Checa

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6-Bromoindigo dye

D. J. Szalda, K. Ramig, O. Lavinda, Z. C. Koren and L. Massa

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3,5-Bis{4-[(benzimidazol-1-yl)methyl]phenyl}-4H-1,2,4-triazol-4-amine and its one-dimensional polymeric complex with HgCl₂

Y. Li, Q.-K. Liu, J.-P. Ma and Y.-B. Dong

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Hydrogen bis[tris(4-fluorophenyl)phosphane oxide] triiodide

F. Haghjoo, N. A. Barnes, R. Pritchard, S. M. Godfrey and S. Ratcliffe

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An example of the refinement of positional disorder modeled as compositional disorder in [5-(2-formylphenyl)-10,15,20-triphenylporphyrinato]nickel(II)

L. C. Spencer, S. A. Yao, J. F. Berry and I. A. Guzei

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4-Carboxypyridinium perchlorate 18-crown-6 dihydrate clathrate and 4-carboxypyridinium tetrafluoroborate 18-crown-6 dihydrate clathrate

P. Shi, L. Zhang and Q. Ye

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Competing intermolecular interactions in some `bridge-flipped' isomeric phenylhydrazones

W. H. Ojala, T. M. Arola, A. M. Brigino, J. D. Leavell and C. R. Ojala

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A new potential NLO compound with a supramolecular layered structure: aqua(hexamethylenetetramine-κN)(iminodiacetato-κ³O,N,O′)copper(II)

J.-J. He, W.-X. Chai, L. Song, F. Niu and X.-B. Fang

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Enantiomerically pure (1S,5R) and racemic 3-(1-benzothiophen-2-yl)-8-azoniabicyclo[3.2.1]oct-2-ene acetate

B. Frøstrup, D. Peters and A. D. Bond

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Structures of benzoxazine-fused triazoles as potential diuretic agents

K. Ravikumar, B. Sridhar, J. B. Nanubolu, V. Hariharakrishnan and A. N. Singh

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1,1′-Methylenedipyridinium tetrachloridocuprate(II) and bis[tetrachloridoaurate(III)] hybrid salts by X-ray powder diffraction

M. Al-Ktaifani and M. Rukiah

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The weakly coordinating perchlorate group in bis(N,N′-dimethylethylenediamine-κ²N,N′)bis(perchlorato-κO)copper(II) studied at 100, 250 and 400 K

S. Schnitzler, M.-D. Şerb and U. Englert

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The heterobifunctional ligand 5-[4-(1,2,4-triazol-4-yl)phenyl]-1H-tetrazole and its role in the construction of a Cd^II metal–organic chain structure

A. B. Lysenko

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Isoquinolin-5-amine

A. M. Atria, M. T. Garland and R. Baggio

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Eight isostructural 4,4′-disubstituted N-phenylbenzenesulfonamides

T. Gelbrich, T. L. Threlfall and M. B. Hursthouse

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2-Propynyl 2,3,4,6-tetra-O-acetyl-α-D-mannopyranoside

H. Al-Mughaid, K. N. Robertson, U. Werner-Zwanziger, M. D. Lumsden, T. S. Cameron and T. B. Grindley

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4-(2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)benzoic acid: X-ray and DFT-calculated structure

R. Moreno-Fuquen, J. C. Tenorio, J. Ellena, C. A. De Simone and L. Ribeiro

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Four stereoisomers of the novel μ-opioid receptor agonist tapentadol hydrochloride

K. Ravikumar, B. Sridhar, N. Pradhan and M. Khunt

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Optically active diaryl tetrahydroisoquinoline derivatives

T. Naicker, T. Govender, H. G. Kruger and G. E. M. Maguire

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1,N⁶-Etheno-2′-deoxytubercidin hemihydrate

F. Seela, P. Ding, P. Leonard, H. Eickmeier and H. Reuter

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(+)-Geodin from Aspergillus terreus

M. H. Rønnest, M. T. Nielsen, B. Leber, U. H. Mortensen, A. Krämer, M. H. Clausen, T. O. Larsen and P. Harris

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A dynamic disorder-linked reversible phase transition in a new chloroform solvate of cis-dichloridobis(triethylphosphane)platinum(II)

K. B. Dillon, J. A. K. Howard, P. K. Monks, M. R. Probert and H. J. Shepherd

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L-Cysteinium semioxalate: a new monoclinic polymorph or a hydrate?

V. S. Minkov and E. V. Boldyreva

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Methyl 2-acetamido-2-deoxy-β-D-glucopyranoside dihydrate and methyl 2-formamido-2-deoxy-β-D-glucopyranoside

X. Hu, W. Zhang, A. G. Oliver and A. S. Serianni

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μ-Acetato-μ-aqua-μ-hydroxido-bis[(1,10-phenanthroline)copper(II)] dinitrate monohydrate

J. E. Abud, R. P. Sartoris, R. Calvo and R. Baggio

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Poly[tetra-μ₂-L-lactato-indium(III)sodium(I)]

J.-J. Wei, N. Zhang, Y.-L. Wang and Q.-Y. Liu

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trans-Dichloridobis(4,8-dimethyl-2-phenyl-2-phosphabicyclo[3.3.1]nonane-κP)platinum(II)

P. N. Bungu, L. Kirsten and S. Otto

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(2R,4S)-2-(Pyridin-3-yl)-2,3,4,5-tetrahydro-1H-1-benzazepin-4-ol: a three-dimensional framework built from O—H⋯N, C—H⋯O and C—H⋯π(arene) hydrogen bonds

S. L. Gómez, A. Palma, J. Cobo and C. Glidewell

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Acidic and anionic forms of 1,3-cyclic dihydroxyacetone phosphate (cDHAP) dimethyl acetal

K. Ślepokura and I. Mitaszewska

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A novel Janus-type AT nucleoside with benzoyl protecting groups forming a pleated-sheet structure

M.-Y. Pan, X.-H. Wu, D.-B. Luo, W. Huang and Y. He

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(R)-4-(4-Aminophenyl)-2,2,4-trimethylchroman and (S)-4-(4-aminophenyl)-2,2,4-trimethylthiachroman

C. S. Frampton, D. D. MacNicol and D. R. Wilson

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An X-ray powder diffraction study of cis-dichloridobis(2-methyl-2H-tetrazol-5-amine-κN⁴)platinum(II), a tetrazole-containing analogue of cisplatin

L. S. Ivashkevich, T. V. Serebryanskaya, A. S. Lyakhov and P. N. Gaponik

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The pentacoordinated [Cr(CO)₅]²⁻ dianion in [2,2,2-crypt-K]₂[Cr(CO)₅] ethylenediamine monosolvate

J. Zhai and L. Xu

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Sodium tris(acetato-κ²O,O′)dioxidoamericate(VI) and guanidinium tris(cyclopropanecarboxylato-κ²O,O′)dioxidoamericate(VI)

M. S. Grigoriev and A. M. Fedosseev

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Two polymorphs of (2-carboxyethyl)(phenyl)phosphinic acid

Q.-S. Hu, X.-Z. Zhang, S.-F. Luo, Y.-H. Sun and Z.-Y. Du

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The molecular conformation of pentan-3-one studied in cholic acid pentan-3-one solvate

I. Kalf and U. Englert

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A chiral interdigitated supramolecular network assembled from single-stranded helical tubes

L. Han, L.-P. Xu and W.-N. Zhao

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Planarity of heteroaryldithiocarbazic acid derivatives showing tuberculostatic activity. III. Mono- and diesters of 3-(pyrazin-2-ylcarbonyl)dithiocarbazic acid

M. Szczesio, A. Olczak, J. Gołka, K. Gobis, H. Foks and M. L. Główka

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β-Carboline (norharman)

R. J. Thatcher and R. E. Douthwaite

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Polysulfonylamines. CXCI. The `almost' polymorphs rac-trans-2-aminocyclohexan-1-aminium di(methanesulfonyl)azanide and its 0.11-hydrate

C. Wölper, N. Anwar, N. Gulzar, P. G. Jones and A. Blaschette

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N-(tert-Butoxycarbonyl)-L-valyl-L-valine methyl ester: a twisted parallel β-sheet in the crystal structure of a protected dipeptide

Ø. Jacobsen, H. G. Gebreslasie, J. Klaveness, P. Rongved and C. H. Görbitz

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2,3-Dimethoxy-10-oxostrychnidinium 2-(2,4,6-trinitroanilino)benzoate monohydrate: a 1:1 proton-transfer salt of brucine with o-picraminobenzoic acid

G. Smith and U. D. Wermuth

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catena-Poly[[[μ-1,3-bis(diphenylphosphanyl)propane-κ²P:P′][O-ethyl (4-methoxyphenyl)phosphonodithioato-κ²S,S′]silver(I)] chloroform monosolvate]

D. Sun and R.-B. Huang

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Tosyl esters of cinchonidine and cinchonine alkaloids: the structure–reactivity relationship in the hydrolysis to 9-epibases

Z. Karczmarzyk, T. M. Lipińska, W. Wysocki, M. Denisiuk and K. Piechocka

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N-(tert-Butoxycarbonyl)-O-allyl-L-seryl-α-aminoisobutyryl-L-valine methyl ester: a protected tripeptide with an allylated serine residue

H. G. Gebreslasie, Ø. Jacobsen and C. H. Görbitz

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(E)-4-[2-(3,4,5-Trimethoxyphenyl)ethenyl]nitrobenzene and its `bridge-flipped' analogues

A. Collas and F. Blockhuys

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Water-induced pseudo-quadruple hydrogen-bonding motifs in xanthine–inorganic acid complexes

B. Sridhar

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Weak C—H⋯O hydrogen bonds in anisaldehyde, salicylaldehyde and cinnamaldehyde

M. T. Kirchner, D. Bläser, R. Boese, T. S. Thakur and G. R. Desiraju

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Plumeridoid C from the Amazonian traditional medicinal plant Himatanthus sucuuba

B. Waltenberger, J. M. Rollinger, U. J. Griesser, H. Stuppner and T. Gelbrich

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New organic–inorganic frameworks incorporating iso- and heteropolymolybdate units and a 3,3′,5,5′-tetramethyl-4,4′-bi-1H-pyrazole-2,2′-diium multiple hydrogen-bond donor

L. V. Lukashuk, A. B. Lysenko, H. Krautscheid and K. V. Domasevitch

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[η⁶-1-Chloro-2-(pyrrolidin-1-yl)benzene](η⁵-cyclopentadienyl)iron(II) hexafluoridophosphate and (η⁵-cyclopentadienyl){2-[η⁶-2-(pyrrolidin-1-yl)phenyl]phenol}iron(II) hexafluoridophosphate

A. D. Hendsbee, J. D. Masuda and A. Piórko

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Two tautomeric polymorphs of 2,6-dichloropurine

M. E. García-Rubiño, D. Choquesillo-Lazarte, M. C. Núñez and J. M. Campos

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Disorder and conformational analysis of methyl β-D-galactopyranosyl-(1→4)-β-D-xylopyranoside

W. Zhang, A. G. Oliver and A. S. Serianni

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Magnesium, calcium and strontium salts of phenylacetic acid

J.-B. Arlin, A. R. Kennedy and K. Shankland

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1-Ferrocenylmethyl-3-(2,4,6-trimethylbenzyl)-1H-imidazolidin-3-ium iodide and trans-bis(3-benzyl-1-ferrocenylmethyl-1H-imidazolidin-2-ylidene)diiodidopalladium(II)

J.-C. Daran, F. Demirhan, Ö. Yıldırım and B. Çetinkaya

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Clarithromycin form I determined by synchrotron X-ray powder diffraction

S. Noguchi, K. Miura, S. Fujiki, Y. Iwao and S. Itai

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Conformational studies of hydantoin-5-acetic acid and orotic acid

V. Gerhardt, M. Tutughamiarso and M. Bolte

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Planarity of heteroaryldithiocarbazic acid derivatives showing tuberculostatic activity. IV. Diesters of benzoylcarbonohydrazonodithioic acid

M. Szczesio, A. Olczak, K. Gobis, H. Foks and M. L. Główka

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Absolute configuration of strictosidinic acid

R. de P. Castro, C. da S. Matos, C. A. do Nascimento, C. M. A. Oliveira, L. Kato, L. M. Lião and J. R. Sabino

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Alkyl-chain disorder in tetraisohexylammonium bromide

M. A. Kelland and A. L. Thompson

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Two new XP(O)[NHC(CH₃)₃]₂ phosphoramidates, with X = (CH₃)₂N and [(CH₃)₃CNH]₂P(O)(O)

M. Pourayoubi, A. Tarahhomi, F. Karimi Ahmadabad, K. Fejfarová, A. van der Lee and M. Dušek

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A 2′-deoxycytidine long-linker click adduct forming two conformers in the asymmetric unit

F. Seela, H. Xiong, S. Budow, H. Eickmeier and H. Reuter

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Four Ni^II complexes with the new cyclam–methylimidazole ligand 1-[(1-methyl-1H-imidazol-2-yl)methyl]-1,4,8,11-tetraazacyclotetradecane

A. G. De Candia, M. Molnar, L. D. Slep and R. Baggio

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catena-Poly[[[(oxamide dioxime-κ²N,N′)copper(II)]-μ-L-tartrato-κ⁴O¹,O²:O³,O⁴] tetrahydrate]: a chiral nanochannel framework hosting solvent water molecules

M. M. Bélombé, J. Nenwa, J. S. T. Wankap Kouamo, S. Ponou and A. Fischer

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Chiral crystals from an achiral molecule: 4,6-di-O-benzyl-1,3-O-benzylidene-2-O-(4-methoxybenzyl)-myo-5-inosose

B. P. Gurale, R. G. Gonnade and M. S. Shashidhar

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Structural study of six cycloalkylammonium cinnamate salt structures featuring one-dimensional columns and two-dimensional hydrogen-bonded networks

A. Lemmerer and M. A. Fernandes

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Redetermination of rifampicin pentahydrate revealing a zwitterionic form of the antibiotic

B. Wicher, K. Pyta, P. Przybylski, E. Tykarska and M. Gdaniec

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Two androsterone derivatives as inhibitors of androgen biosynthesis

G.-B. Djigoue, M. Simard, L.-C. Kenmogne and D. Poirier

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XRD and VCD: a marriage of love or convenience? Honeymoon around a cyclic urea derivative

D. Gherase, J.-V. Naubron, C. Roussel and M. Giorgi

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KCo(H₂O)₂BP₂O₈·0.48H₂O and K_0.17Ca_0.42Co(H₂O)₂BP₂O₈·H₂O: two cobalt borophosphates with helical ribbons and disordered (K,Ca)/H₂O schemes

A. Guesmi and A. Driss

The two investigated compounds have similar [CoBP₂O₈]⁻ anionic frameworks but differ in their (K,Ca)/H₂O disorder schemes. In the structure of the pure potassium borophosphate, the solvent water molecules and a fraction of the alkali cations are located within the helical channels.

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