From a 1D Sb Coordination Polymer to a 3D Sb Framework with Pyrazine: Switching off the Stereochemically Active Lone‐Pair

The one‐dimensional coordination polymer 1∞[SbCl3(pyz)] (1) and the three‐dimensional frameworks 3∞[Sb2Cl6(pyz)3] (2) and 3∞[Sb2I6(pyz)3] (3) were obtained from SbX3 (X: Cl, I) and pyrazine (pyz). These coordination polymers are, to the best of our knowledge, among the first Sb‐based coordination polymers constructed from antimony halides and N‐donor ligands. While the Sb3+‐cations in 1 are coordinated in a square‐pyramidal coordination sphere indicating a stereochemically active lone‐pair, no stereochemically active Sb‐lone‐pair is present in 2 and 3 having octahedral coordination spheres around SbIII. Since 2 can be obtained by heating of 1, the character of the Sb‐lone‐pair in 1 can be changed by thermal treatment. Thereby the interlinkage is increased via an additional pyrazine molecule resulting in the octahedral coordination in 2.