Typical interatomic distances: organic compounds

Allen, Frank H.; Watson, D. G.; Brammer, Lee; Orpen, A. Guy; Taylor, Richard E.

doi:10.1107/97809553602060000621

Cited by 227 publications

(206 citation statements)

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“…The C6-O bond in this enol-imino tautomer is comparable to those in phenols (1.362(15) Å), 30 and the C7-N bond, to those in imines (1.279(8) Å). 30 Lindeman et al 31,32 suggested that N-salicylidene-4-chloroaniline (planar) and N-salicylidene-4-bromoaniline (nonplanar) differ mainly by their conformations, whereas the other geometrical parameters were close to each other. Indeed, we observed that distances and angles of 1 are similar to those found in the nonplanar R 2 -polymorph.…”

Section: Resultsmentioning

confidence: 55%

Polymorphism inN-Salicylideneaniline Reconsidered

Arod

Pattison

Schenk

et al. 2007

Crystal Growth & Design

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ABSTRACT:The aromatic Schiff base N-salicylideneaniline (SA) represents the aristotype of a whole family of chromic derivatives. SA forms two photochromic polymorphs, R 1 and R 2 , both of which feature non-coplanar phenyl rings. Since many details of its reversible photoreactivity are still unexplained, we report the structure of a planar, thermochromic polymorph, named , and propose a new model for the structure of the R 1 -polymorph. Finally, we discuss structure-property relations between the polymorphs and the to R 1 phase transition.

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Section: Resultsmentioning

confidence: 55%

Polymorphism inN-Salicylideneaniline Reconsidered

Arod

Pattison

Schenk

et al. 2007

Crystal Growth & Design

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“…This group is almost coplanar with aromatic ring. All relevant structural parameters (bond distances and angles) are as expected and in acceptable agreement with other organic molecules [25]. Crystallographic data reported in this paper for compound 3e has been deposited at the Cambridge Crystallographic Data Center (CCDC), No.…”

Section: Resultsmentioning

confidence: 69%

Efficient MW-Assisted Synthesis, Spectroscopic Characterization, X-ray and Antioxidant Properties of Indazole Derivatives

et al. 2016

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A small series of tetrahydroindazoles was prepared, starting from 2-acetylcyclohexanone and different hydrazines using reflux and a focused microwave reactor. Microwave irradiation (MW) favored the formation of the desired products with improved yields and shortened reaction times. This is a simple and green method for the synthesis of substituted tetrahydroindazole derivatives. The in vitro antioxidant activity was evaluated using the DPPH and ABTS methods. In these assays, 2-(4-fluorophenyl)-3-methyl-4,5,6,7-tetrahydro-2H-indazole (3f) showed moderate DPPH decoloring activity, while 3-methyl-4,5,6,7-tetrahydro-1H-indazole (3a), 3-methyl-2-phenyl-4,5,6,7-tetrahydro-2H-indazole (3b) and 2-(4-fluorophenyl)-3-methyl-4,5,6,7-tetrahydro-2H-indazole (3f) were the most active in the ABTS assay. All compounds were well characterized by IR, 1 H-, 13 C-NMR and GC-MS spectroscopy and physical data, while the structure of 4-(3-methyl-4,5,6,7-tetrahydro-2H-indazol-2-yl)benzoic acid (3e) was also determined by single crystal X-ray analysis.

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“…C in ch. 9.5 (Allen et al, 2006). The distances and angles remain constant within the standard uncertainties along the fourth dimension, i.e.…”

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confidence: 80%

A non-mathematical introduction to the superspace description of modulated structures

Wagner

Schönleber

2009

Acta Crystallogr Sect B

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The X-ray analysis of (6R,7aS)-6-(tert-butyl-dimethylsilanyloxy)-1-hydroxy-2-phenyl-5,6,7,7a-tetrahydropyrrolizin-3-one, C 19 H 27 NO 3 Si, revealed a diffraction pattern which is typical for modulated structures: strong Bragg peaks surrounded by weaker reflections which cannot be indexed with the same three reciprocal lattice vectors that are used to describe the strong peaks. For this class of crystal structures the concept of superspace has been developed which, however, for many crystallographers still constitutes a Gordian Knot. As a possible tool to cut this knot the crystal structure of the above-mentioned tetrahydropyrrolizinone derivative is presented as an illustrative example for handling and describing the modulated structure of a typical pharmaceutical (i.e. molecular) compound. Having established a working knowledge of the concepts and terminology of the superspace approach a concise and detailed description of the complete process of peak indexing, data processing, structure solution and structure interpretation is presented for the incommensurately modulated crystal structure of the above-mentioned compound. The superspace symmetry applied is P2 1 (0)0; the (incommensurate) q vector components at 100 K are = 0.1422 (2) and = 0.3839 (8).

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Typical interatomic distances: organic compounds

Cited by 227 publications

References 0 publications

Polymorphism inN-Salicylideneaniline Reconsidered

Polymorphism inN-Salicylideneaniline Reconsidered

Efficient MW-Assisted Synthesis, Spectroscopic Characterization, X-ray and Antioxidant Properties of Indazole Derivatives

A non-mathematical introduction to the superspace description of modulated structures

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