Cvrtila Ivica, Stilinović Vladimir
Department of Chemistry, Faculty of Science, Horvatovac 102a, Zagreb 10000, Croatia.
Acta Crystallogr B Struct Sci Cryst Eng Mater. 2021 Apr 1;77(Pt 2):211-218. doi: 10.1107/S2052520621000275. Epub 2021 Mar 10.
The crystal structures of two polymorphs of a phenazine hexacyanoferrate(II) salt/cocrystal, with the formula (Hphen)[HFe(CN)][HFe(CN)]·2(phen)·2HO, are reported. The polymorphs are comprised of (Hphen)[HFe(CN)] trimers and (Hphen)[(phen)(HO)][HFe(CN)] hexamers connected into two-dimensional (2D) hydrogen-bonded networks through strong hydrogen bonds between the [HFe(CN)] and [HFe(CN)] anions. The layers are further connected by hydrogen bonds, as well as through π-π stacking of phenazine moieties. Aside from the identical 2D hydrogen-bonded networks, the two polymorphs share phenazine stacks comprising both protonated and neutral phenazine molecules. On the other hand, the polymorphs differ in the conformation, placement and orientation of the hydrogen-bonded trimers and hexamers within the hydrogen-bonded networks, which leads to different packing of the hydrogen-bonded layers, as well as to different hydrogen bonding between the layers. Thus, aside from an exceptional number of symmetry-independent units (nine in total), these two polymorphs show how robust structural motifs, such as charge-assisted hydrogen bonding or π-stacking, allow for different arrangements of the supramolecular units, resulting in polymorphism.
报道了一种吩嗪六氰合铁（II）盐/共晶体两种多晶型物的晶体结构，其化学式为(Hphen)[HFe(CN)][HFe(CN)]·2(phen)·2HO。这些多晶型物由(Hphen)[HFe(CN)]三聚体和(Hphen)[(phen)(HO)][HFe(CN)]六聚体组成，它们通过[HFe(CN)]和[HFe(CN)]阴离子之间的强氢键连接成二维（2D）氢键网络。这些层通过氢键以及吩嗪部分的π-π堆积进一步连接。除了相同的二维氢键网络外，这两种多晶型物共享包含质子化和中性吩嗪分子的吩嗪堆积。另一方面，多晶型物在氢键网络中氢键连接的三聚体和六聚体的构象、位置和取向上有所不同，这导致氢键层的堆积不同，以及层间氢键不同。因此，除了数量异常多的对称独立单元（总共九个）外，这两种多晶型物展示了诸如电荷辅助氢键或π堆积等强大的结构基序如何允许超分子单元有不同的排列，从而导致多晶型现象。
