LnCl(CN₂) with Ln = La, Ce, and Pr: Synthesis and Structure of a New Lanthanide Chloride Cyanamide Related to the PbFCl‐Type Structure

Abstract

Abstract Solid state metathesis reactions between LaCl 3 and Li 2 (CN 2 ) carried out in silica ampoules at 600 °C over two days resulted in the formation of a light gray powder, later identified to be lanthanum chloride cyanamide. Single crystals were obtained as colourless transparent plates using a LiCl‐KCl flux. The crystal structure of LaCl(CN 2 ) was solved and refined from X‐ray single crystal data (P2 1 /m (no. 11), Z = 2, a = 5.330(1) Å, b = 4.0305(8) Å, c = 7.545(1) Å, V = 159.24(5) Å 3 , β = 100.75(2)°). The structure of LaCl(CN 2 ) is closely related to the tetragonal LaOCl (PbFCl type) structure and contains a [La 2 Cl 2 ] 4+ block layer and two layers of (CN 2 ) 2‐ ions in an alternating sequence. The La 3+ ion in LaCl(CN 2 ) is situated in a polyhedron composed of four chloride ions on one side and five cyanamide ions on the other side. Cerium and praseodymium analogues were identified from indexed powder patterns with analogous unit cells, assuming them to form isostructural compounds.