A new mixed halide 2D hybrid perovskite: Structural, thermal, optic and magnetic properties

A new copper(II) bromide/chloride complex templated by 1,4-diaminobutane, (C4H14N2)[CuBr2.19Cl1.81], was synthesized and crystallographically characterized by single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic space group P2(1)/c with two formula units per cell and the following parameters: a = 9.3580(10) angstrom; b = 7.7360(10) angstrom; c = 7.7590(10) angstrom, beta = 102.833(9)degrees and V = 547.67(12) angstrom(3). Its 2D perovskite structure consists of metallic layers parallel to the bc-plane, obtained by corner sharing between octahedra built of copper(II) cations surrounded by six bromide/chloride anions, and diprotonated diamine cations lying in the space between the anionic layers. The thermal decomposition of the compound proceeds through two stages giving rise to copper oxide as the final product. The optical study reveals that the title compound exhibits three optical absorption bands at 318, 460 and 754 nm. The gap energy value is 3.21 eV, which shows that the new hybrid compound is a semiconducting material. The title compound is well-modelled as a 2D-ferromagnetic layer (average J = 12.8(2) K) without any indication of long-range order down to 1.8 K. The lack of order likely arises from the random interactions and anisotropy introduced by the mixed chloride/bromide substituents. (C) 2019 Elsevier Ltd. All rights reserved.