Reaction of MX₂ (M = Cd, Zn; X = Cl, Br, I) with 2‐cyanopyrazine leads to the formation of compounds with the composition CdX₂(2‐cyanopyrazine)₂ (X = Cl; CdCl, X = Br; CdBr and X = I; CdI) and ZnX₂(2‐cyanopyrazine)₂ (X = Cl; ZnCl, X = Br; ZnBr and X = I; ZnI/I). In the crystal structures of the Cd compounds and in ZnCl, the metal cations are octahedrally coordinated and are linked into chains by the halide anions via common edges. In contrast, in the crystal structures of ZnBr and ZnI/I the metal cations are tetrahedrally coordinated into discrete complexes. Further investigations show that a second modification of ZnCl₂(2‐cyanopyrazine)₂ exists (ZnI/II), which is formed by kinetic control. The thermal properties of the 2‐cyanopyrazine rich compounds were investigated by TG‐DTA and temperature dependent XRPD measurements. Upon heating the Cd compounds, all 2‐cyanopyrazine ligands are removed in a single step with no indication of the formation of a 2‐cyanopyrazine deficient phase. A similar behavior is observed for ZnI, whereas for ZnCl and ZnBr, TG‐DTA measurements suggest the formation of a 2‐cyanopyrazine deficient phase that, in case of ZnBr, cannot be isolated and, for ZnCl, cannot be obtained pure. The emission of these compounds is shifted from the blue to orange depending on the crystal structure and the nature of the halide anion.

中文翻译：

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2-氰基吡嗪锌和镉卤化物配位聚合物的合成，结构，热和发光性质

MX ₂（M = Cd，Zn; X = Cl，Br，I）与2-氰基吡嗪的反应导致形成具有CdX ₂（2-氰基吡嗪）₂（X = Cl; CdCl，X = Br ; CdBr和X = I; CdI）和ZnX ₂（2-氰基吡嗪）₂（X = Cl; ZnCl，X = Br; ZnBr和X = I; ZnI / I）。在Cd化合物的晶体结构和ZnCl中，金属阳离子是八面体配位的，并通过卤化物阴离子通过共同的边缘连接成链。相反，在ZnBr和ZnI / I的晶体结构中金属阳离子四面体配位成离散的络合物。进一步的研究表明，存在通过动力学控制形成的ZnCl ₂（2-氰基吡嗪）₂的第二种修饰形式（ZnI / II）。通过TG-DTA和温度依赖性XRPD测量研究了富含2-氰基吡嗪的化合物的热性质。加热Cd化合物后，只需一步即可除去所有2-氰基吡嗪配体，没有迹象表明形成了2-氰基吡嗪缺陷相。对于ZnI观察到类似的行为，而对于ZnCl和ZnBr，TG-DTA测量表明形成了2-氰基吡嗪缺陷相，在ZnBr的情况下不能分离，对于ZnCl不能纯。这些化合物的发射从蓝色转移到橙色，具体取决于晶体结构和卤化物阴离子的性质。