Investigations on the thermal decomposition of coordination polymers basedon copper(I) halides and 2-methylpyrazine

The thermal behaviour of the three coordination polymers (2)(infinity)poly [CuX(mu -2-methylpyrazine-N,N')] (X = Cl (I), Br (II)), and (2)(infinity)po ly[{Cu2I2 (mu -pyrazine-N,N')2} . 2-methylpyrazine] (III) was investigated using differential thermal analysis and thermogravimetry (DTA-TG) measureme nts as well as temperature resolved X-ray powder diffraction in argon and i n air. On heating all compounds decompose in two steps. In the first step c ompound I and II loose one and compound III looses two of the 2-methylpyraz ine ligands to form the corresponding 2:1 compounds Cu2Cl2(2-methylpyrazine ) (IV) and (2)(infinity)poly[Cu2X2(mu -2-methylpyrazine-N,N')] (X = Br (V), I (VI)). From the experiments there is no evidence for the formation of a 1: 1 compound of CUI and 2-methylpyrazine as an intermediate phase during t he thermal decomposition. On further heating the 2:1 compounds IV, V and VI transform directly to the corresponding copper(I) halides.