Polymorphism in silver thiocyanate: preparation of a new phase and its chaacterization by X-ray powder diffraction

A new crystalline phase of silver thiocyanate, AgSCN, has been prepared in the presence of gelatin. X-ray powder diffraction data were indexed for an orthorhombic cell with a = 4.083 (1), b = 7.043 (1), c = 11.219 (2) Å, Z = 4. The crystal structure was solved and refined in Pmnn to R_F = 0.11 from 54 peak-height powder intensities. Strongly bonded, approximately linear AgNCS units [Ag-N = 2.00(5) Å] are joined together into a three-dimensional polymeric network by three long Ag-S bonds [2.70(2), 2 × 2.64(1) Å]. The configurations at both Ag and S are intermediate between tetrahedral and trigonal pyramidal.