[(C 6 H 5 ) 4 P] ∞ 1 [Cu 3 I 4 ]—The First Compound with a Helical Chain of Face‐Sharing Tetrahedra as a Structural Element

Face‐sharing tetrahedra arranged in a helix (idealized form shown below) mark the structure of the iodocuprate 1 , which was obtained from Ph 4 PI, I 2 , and Cu. Five Cu positions were identified at room temperature; at lower temperatures only three (slow cooling) or four (rapid cooling) are occupied.