Synthesis and Structure Solution of Ba[SeCN] ₂

Barium selenocyanate, Ba[SeCN] 2 , was synthesized from Ba[OH] 2 and [NH 4 ][SeCN] in THF. As single crystals suitable for structure determination could not be obtained, the crystal structure was solved from high‐resolution powder X‐ray diffraction (PXRD) data. Variable‐temperature PXRD showed that thermal treatment at 200 °C markedly improves crystallinity and permits reliable indexing and subsequent structure solution. Ba[SeCN] 2 crystallizes in the monoclinic space group C 2/ c (No. 15; a = 12.0242(2) Å, b = 7.0430(1) Å, c = 7.2515(1) Å, β = 101.3894(11)°) and represents a new structure type. The Ba 2+ cation is coordinated by four N and four Se atoms of eight [SeCN] − anions in the form of a distorted tetragonal antiprism. Raman spectroscopic measurements supported by periodic density functional theory (DFT) calculations enabled assignment of the principal internal vibrational modes of the selenocyanate anion. The present study provides the first detailed structural characterization of a binary alkaline earth metal selenocyanate and expands the family of structurally characterized binary inorganic selenocyanates.