Cluster Helix Structure of the Binary Compound W 5 I 12

The binary tungsten iodide W 5 I 12 forms an unprecedented one‐dimensional helical structure. A crystal structure refinement performed on basis of X‐ray powder diffraction data revealed the space group P6 1 [Z = 6, a = 993.97(2) pm, c = 4226.73(9) pm]. The crystal structure is based on [(W 5 I 8 i )I 3 a I 2/2 a‐a ] clusters, interconnected by two shared apical iodido ligands to form helical chain arrangements.