期刊论文详细信息
Acta Crystallographica Section E: Crystallographic Communications
Crystal structure of (4R,5S,6R)-6-azido-5-benzyloxy-3,3,4-trifluoroazepan-1-ium 2,2,2-trifluoroacetate from synchrotron data
Fei Liu1  Alpesh Ramanlal Patel1  Mohan M. Bhadbhade2 
[1] Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia;Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, 2052 NSW, Australia;
关键词: crystal structure;    azepane;    fluorination;    fluorine gauche effect;    hydrogen bonding;   
DOI  :  10.1107/S2056989015019416
来源: DOAJ
【 摘 要 】

The structure of the title compound, C15H16F6N4O3, was determined using synchrotron radiation on an extremely small crystal (0.015 × 0.01 × 0.01 mm). Although the diffraction was weak, leading to high residuals and a poor data-to-parameter ratio, the data allowed ready solution and refinement to reveal the entire structure. The solid-state structure is in accordance with the absolute configuration assigned based on that of the known starting material. The compound comprises a highly substituted seven-membered N-heterocyclic cation and a trifluoromethanesulfonate counter-anion. The title compound crystallizes with two independent cations (A and B) and anions (C and D) in the asymmetric unit. Two geminal F atoms, a single F atom, a benzyl ether and an azide group are substituted on consecutive C atoms between the NH2 and CH2 units of the azepan-1-ium ring system. The seven-membered rings adopt different conformations with the principal differences occurring in the CF2CHFCH2 segments of the ring systems. The geminal F atoms on the quaternary C atom exhibit essentially identical bond angles [109 (2) and 106 (2)°] in the two independent molecules. The two molecules associate as a dimeric unit via two C—H...F interactions. An extensive series of N—H...O, N—H...F, C—H...O, C—H...N, C—H...F and C—H...π contacts generate a three-dimensional network with cations and anions linked into ABCD repeat columns along a.

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