The structure of (SCN)(x): a study using molecular and solid-state density functional theory calculations.

A riddle solved! Despite its simple formula, the structure of the (SCN)(x) polymer has remained elusive since its first synthesis in 1929. From energetics as well as NMR chemical shifts, based on DFT calculations, we have strong evidence that it is indeed a tangle of linear chains, made up from N-linked S(2)C(2)N five-membered rings.Molecular fragments and crystal structures based on proposed structures for polythiocyanogen were studied by using molecular and solid-state electronic structure calculations at the density functional theory level. The energetics and chemical shifts from both types of calculations indicate that a planar N-linked chain consisting of 1,2,4-dithiazole five-membered rings with adjacent rings pointing in opposite directions is the most likely local structure of the (SCN)(x) polymer.