Bi₁₁Se₁₂Cl₉: Synthesis and Crystal Structure

The Bi₁₁Se₁₂Cl₉ phase (I), previously known as BiSeCl, is synthesized by the ampule technique. The X-ray crystal structure of I is determined (space group Cm, a = 36.444(5) Å, b = 4.0844(6) Å, c = 12.073(2) Å, β = 91.16(1)○, Z = 2). The structure of I consists of alternating _∞ ¹[BiSe] double zigzag chains. Bismuth atoms are hexa- and heptacoordinated with selenium and chlorine atoms. Similarities and dissimilarities between crystal structures of I and SbSBr are discussed. It is shown that compounds A^VB^VIC^VII, regardless of their specific crystal structure, are characterized by covalent metal-chalcogen bonds and mainly ionic metalhalogen bonds.