Crystals 2012, 2(3), 1347-1356; doi:10.3390/cryst2031347
Article

Temperature-Dependent Ordering of the Methyl Group in the Crystal Structure of 5-(2-Chlorophenyl)-7-ethyl-1H-thieno [2,3-E][1,4]diazepin-2(3H)-one

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Received: 15 May 2012; in revised form: 23 July 2012 / Accepted: 26 July 2012 / Published: 18 September 2012
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: 5-(2-Chlorophenyl)-7-ethyl-1H-thieno[2,3-e][1,4]diazepin-2(3H)-one, a close analogue of clotiazepam (full agonist at GABA receptor), crystallizes in monoclinic P21/c space group with a = 15.6941(6) Å, b = 10.7909(4) Å, c = 8.6586(3) Å, and β = 102.184(4)° (at 125 K). Seven-Membered diazepine ring has approximate mirror plane of symmetry, planar thieno and phenyl rings are almost perpendicular to one another, dihedral angle between their mean planes is 84.11(5)°. N–H···O hydrogen bonds connect molecules into centrosymmetric dimers which are further expanded into 3D crystal structure with the help of weaker C–H···O and C–H···π interactions. The methyl group is disordered at room temperature, but it gets gradually ordered at lower temperatures and becomes fully ordered at approximately 200 K. The changes in structure with temperature were studied between 125 and 380 K. The unit cell volume—as expected—increases almost monotonically when the temperature rises, but one of the parameters shortens significantly.
Keywords: diazepines; hydrogen bonding; disorder; structural change
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MDPI and ACS Style

Dutkiewicz, G.; Kubicki, M.; Dayananda, A.S.; Yathirajan, H.S.; Ramesha, A.R. Temperature-Dependent Ordering of the Methyl Group in the Crystal Structure of 5-(2-Chlorophenyl)-7-ethyl-1H-thieno [2,3-E][1,4]diazepin-2(3H)-one. Crystals 2012, 2, 1347-1356.

AMA Style

Dutkiewicz G, Kubicki M, Dayananda AS, Yathirajan HS, Ramesha AR. Temperature-Dependent Ordering of the Methyl Group in the Crystal Structure of 5-(2-Chlorophenyl)-7-ethyl-1H-thieno [2,3-E][1,4]diazepin-2(3H)-one. Crystals. 2012; 2(3):1347-1356.

Chicago/Turabian Style

Dutkiewicz, Grzegorz; Kubicki, Maciej; Dayananda, Alaloor S.; Yathirajan, Hemmige S.; Ramesha, Andagar R. 2012. "Temperature-Dependent Ordering of the Methyl Group in the Crystal Structure of 5-(2-Chlorophenyl)-7-ethyl-1H-thieno [2,3-E][1,4]diazepin-2(3H)-one." Crystals 2, no. 3: 1347-1356.

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