STATISTICAL-ANALYSIS OF NONCOVALENT INTERACTIONS OF ANION GROUPS IN CRYSTAL-STRUCTURES .2. HYDROGEN-BONDING OF THIOCYANATE ANIONS

The hydrogen-bond acceptor function of the thiocyanate anion is analyz ed in 52 crystal structures retrieved from the Cambridge Crystallograp hic Database. All modes of hydrogen-bond coordination are represented: by the sulfur, by the nitrogen and by the pi-system of the anion. The preferred areas for the H donors (D=OH and NH groups) were determined : (a) around sulfur, as a torus centered at the S end, the axis of whi ch is the linear anion, and with an average DSN angle of 99 degrees, a nd (b) around nitrogen, on a spherical cap delimited by the solid angl e, SND (average = 145 degrees), with the linear anion. The anion-accep tor function is characterized by bonding and, in most cases hydrogen t hiocyanate binds through both acceptor centers (S and N). Important ba ckbonding of sulfur in the thiocyanate anion is structurally evidenced .