Competition between Halogen and Hydrogen Bonds in Triiodoimidazole Polymorphs
详细信息 查看全文
- 作者：Kacper W. Rajewski ; Michał Andrzejewski ; Andrzej Katrusiak
- 刊名：Crystal Growth & Design
- 出版年：2016
- 出版时间：July 6, 2016
- 年：2016
- 卷：16
- 期：7
- 页码：3869-3874
- 全文大小：409K
- 年卷期：0
- ISSN：1528-7505
文摘
Three polymorphs of 2,4,5-triiodo-1H-imidazole (tIIm), all of exceptionally low symmetry (with three and four independent molecules), differ in the contributions of halogen bonds to their cohesion forces. The crystals of phase α, of monoclinic space group P21/c and Z′ = 3, were obtained after the first synthesis of the compound and several of its crystallizations. Above 1.9 GPa phase α isostructurally transformed to phase β. The transition, marked by a huge strain visibly changing the crystal shape, could be reversibly repeated on increasing and releasing pressure. Repeated syntheses of tIIm, by using the same recipe as well as the same and varied conditions, resulted exclusively in a new γ phase, of monoclinic space group P21/c and Z′ = 4, while phase α disappeared. Each of phases α, β, γ is built of Z′ independent molecules and linked by Z′ independent NH···N bonds into chains. In phases β and γ new I···I bonds are formed when one of the NH···N bonds is bent to about 130°.