BaCu(OH)3Cl: a new one-dimensional Mott insulator with a CuO2 chessboard layer

Abstract

In order to obtain a Ba analogue of the Mott insulator SrCu(OH)₃Cl, a new structure-type compound BaCu(OH)₃Cl has been synthesized by a hydrothermal method. The crystal structure of the title compound consists of an undulating [BaCl]⁺ layer and a plane of [Cu(OH)₃]⁻ single chains, stacking alternately along the c-axis. The [Cu(OH)₃]⁻ single chains composed of corner-sharing [CuO₄] squares are isolated in the plane and connected by barium atoms from the next layers. The Cu²⁺ ions from the isolated chains form a two-dimensional chessboard layer of CuO₂, similar to those in the quasi-one-dimensional Mott insulator Sr₂CuO₃ and the superconductor Sr₂CuO_3+δ. The chessboard layers of CuO₂ have been proposed to be responsible for high-temperature superconductivity. Magnetic susceptibility measurements indicate that the title compound has a nearly ideal spin-1/2 antiferromagnetic Heisenberg chain (spin Hamiltonian H = J∑S_iS_i+1) with an intrachain coupling constant J/k_B = 135.7(6) K. The title compound as a quasi-one-dimensional Mott insulator with the characteristic chessboard layer of CuO₂ provides a new prototype for doped derivatives in the search for high-temperature superconductors.