The structure of catena-poly[[potassium-tri-μ-di-methyl-acetamide-κ(6) O:O] iodide], {[K(C4H9NO)3]I} n , at 120 K has trigonal (P-3) symmetry. The structure adopts a linear chain motif parallel to the crystallographic c axis. Two crystallographically independent K(+) cations are present in the asymmetric unit located on threefold rotoinversion axes at [0, 0, 0] and [0, 0, 1/2] and are bridged by the O atoms of the acetamide moiety. This is an example of a rare μ2-bridging mode for di-methyl-acetamide O atoms. The iodide counter-ion resides on a threefold rotation axis in the channel formed by the [K(C4H9NO)](+) chains.
Keywords: crystal structure; dimethylacetamide; one-dimensional coordination polymer; potassium salt; symmetry.