Crystal structure of Cu3Bi(TeO3)2O2Cl: a Kagomé lattice type compound

Single crystals of Cu3Bi(TeO3)2O2Cl were synthesised via a transport reaction in sealed evacuated quartz glass tubes from a starting mixture of CuO, CuCl2, Bi2O3, and TeO2. The new compound Cu3Bi(TeO3)2O2Cl crystallizes in the orthorhombic space group Pcmn, a=6.3179(8), b=9.8524(12), c=14.358(2)Å, Z=4. Full matrix least squares refinement gave an R1 value of 0.0372 using 936 independent reflections. The structure is a layered compound where the building units are [Cu1O4] square planes, [Cu2O4Cl] square pyramids, [BiO6+2] polyhedra, and [TeO3E] tetrahedra (E being the 5s2 lone pair of Te(IV)), joined through sharing of edges and corners. The Cu ions in the CuO layers resemble a distorted Kagomé lattice. The CuO planes are only connected by the two longest BiO bonds (2.83 Å) in the [BiO6+2] coordination polyhedra. The Cl ions and the Te lone pairs are located in tunnels in the structure along [001].