Crystallographic and molecular mechanics investigation of an order-disorder transition and dimorphism in 5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione

Z H Chohan, W T A Harrison, R A Howie, B F Milne, J L Wardell

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Abstract

Single-crystal X-ray structures are presented for three forms of 5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione. The alpha (at 150 K) and alpha' (at ambient) forms are very similar and differ only in the presence of crystallographic m symmetry in the molecules of alpha', which is absent in the case of alpha. This pair is related by an order-disorder transition. The beta phase (also determined at 150 K) has a different structure in terms of the molecular packing from either of the other two and therefore constitutes a true polymorph. Molecular mechanics calculations indicated that the most stable CHCl3-solvated conformations for the title compound were a pair of twisted U-shaped enantiomers, U-R and U-L, i.e. similar to the arrangements found in the alpha and beta phases, with the low-lying saddle point between them corresponding to the situation in the alpha' phase. These calculations also indicated that the most stable CHCl3-solvated conformation for the related dibromo-5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione was Z-shaped, in agreement with the crystal structure determined earlier for its DMSO solvate [Wang et al. (1998). Synthesis, pp. 1615-1618].

Original languageEnglish
Pages (from-to)1011-1017
Number of pages7
JournalActa Crystallographica Section B, Structural Science
Volume56
Publication statusPublished - 2000

Cite this

@article{7eff2bbe355c496b8e4f89e52eb0b85d,
title = "Crystallographic and molecular mechanics investigation of an order-disorder transition and dimorphism in 5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione",
abstract = "Single-crystal X-ray structures are presented for three forms of 5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione. The alpha (at 150 K) and alpha' (at ambient) forms are very similar and differ only in the presence of crystallographic m symmetry in the molecules of alpha', which is absent in the case of alpha. This pair is related by an order-disorder transition. The beta phase (also determined at 150 K) has a different structure in terms of the molecular packing from either of the other two and therefore constitutes a true polymorph. Molecular mechanics calculations indicated that the most stable CHCl3-solvated conformations for the title compound were a pair of twisted U-shaped enantiomers, U-R and U-L, i.e. similar to the arrangements found in the alpha and beta phases, with the low-lying saddle point between them corresponding to the situation in the alpha' phase. These calculations also indicated that the most stable CHCl3-solvated conformation for the related dibromo-5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione was Z-shaped, in agreement with the crystal structure determined earlier for its DMSO solvate [Wang et al. (1998). Synthesis, pp. 1615-1618].",
author = "Chohan, {Z H} and Harrison, {W T A} and Howie, {R A} and Milne, {B F} and Wardell, {J L}",
year = "2000",
language = "English",
volume = "56",
pages = "1011--1017",
journal = "Acta Crystallographica Section B, Structural Science",
issn = "0108-7681",
publisher = "International Union of Crystallography",

}

TY - JOUR

T1 - Crystallographic and molecular mechanics investigation of an order-disorder transition and dimorphism in 5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione

AU - Chohan, Z H

AU - Harrison, W T A

AU - Howie, R A

AU - Milne, B F

AU - Wardell, J L

PY - 2000

Y1 - 2000

N2 - Single-crystal X-ray structures are presented for three forms of 5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione. The alpha (at 150 K) and alpha' (at ambient) forms are very similar and differ only in the presence of crystallographic m symmetry in the molecules of alpha', which is absent in the case of alpha. This pair is related by an order-disorder transition. The beta phase (also determined at 150 K) has a different structure in terms of the molecular packing from either of the other two and therefore constitutes a true polymorph. Molecular mechanics calculations indicated that the most stable CHCl3-solvated conformations for the title compound were a pair of twisted U-shaped enantiomers, U-R and U-L, i.e. similar to the arrangements found in the alpha and beta phases, with the low-lying saddle point between them corresponding to the situation in the alpha' phase. These calculations also indicated that the most stable CHCl3-solvated conformation for the related dibromo-5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione was Z-shaped, in agreement with the crystal structure determined earlier for its DMSO solvate [Wang et al. (1998). Synthesis, pp. 1615-1618].

AB - Single-crystal X-ray structures are presented for three forms of 5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione. The alpha (at 150 K) and alpha' (at ambient) forms are very similar and differ only in the presence of crystallographic m symmetry in the molecules of alpha', which is absent in the case of alpha. This pair is related by an order-disorder transition. The beta phase (also determined at 150 K) has a different structure in terms of the molecular packing from either of the other two and therefore constitutes a true polymorph. Molecular mechanics calculations indicated that the most stable CHCl3-solvated conformations for the title compound were a pair of twisted U-shaped enantiomers, U-R and U-L, i.e. similar to the arrangements found in the alpha and beta phases, with the low-lying saddle point between them corresponding to the situation in the alpha' phase. These calculations also indicated that the most stable CHCl3-solvated conformation for the related dibromo-5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione was Z-shaped, in agreement with the crystal structure determined earlier for its DMSO solvate [Wang et al. (1998). Synthesis, pp. 1615-1618].

M3 - Article

VL - 56

SP - 1011

EP - 1017

JO - Acta Crystallographica Section B, Structural Science

JF - Acta Crystallographica Section B, Structural Science

SN - 0108-7681

ER -