Crystal structure determination of a series of small organic compounds from powder data

Abstract

The crystal structures of 2,4-di-bromo-aniline (A; C₆H₅NBr₂ ), 4-iodo-anisole (B; C₇H₇OI), 2-iodo-benzenemethanol (C; C₇H₇OI), 2-amino-benzothiazole (D; C₇H₆N₂S) and 2-amino, 5-bromo-pyridine (E; C₅H₅N₂Br) have been determined from X-ray powder diffraction data. Grid search and Rietveld refinement have been used to determine the structures. The crystals of (A) and (B) are orthorhombic, the crystals of (C), (D) and (E) are monoclinic. (A): Space group P2₁2₁2₁, Z=4 with cell parameters a = 11.18(1), b = 16.17(1), c = 4.110(3)Å; (B): Space group Pca2₁, Z = 4, a = 6.288(4), b = 7.361(4), c = 16.93(1)Å; (C): Space group P2₁/n, Z = 4, a = 13.23(1), b = 4.652(3), c = 12.82(1)Å, β = 109.69(4)°; (D): Space group P2₁/c, Z = 4, a = 14.58(2), b = 4.094(4), c = 11.62(1)Å, β = 94.12(6)°; (E): Space group P2₁/c, Z = 4, a = 13.80(1), b = 5.839(5), c = 7.687(7)Å, β = 106.04(5)°. Chemical diagrams of all five compounds are depicted in Fig. 1. Soft constraints have been applied to the molecules during Rietveld refinement. The final R_p values obtained were 7.3 (A), 2.9 (B), 11.1 (C), 16.4 (D) and 7.9% (E) respectively. All compounds were measured on a Guinier camera. In addition, the structure of compound (A) was confirmed by single-crystal structure determination.