Layered niobium titanium oxychloride cluster compounds with six-member ring opening channels

Abstract

New niobium oxychloride cluster compounds corresponding to the general formula, A 5Ti 8Nb 18Cl 53O 12 ( A=K, In), have been prepared in sealed quartz tubes from a mixture containing NbCl 5, Nb 2O 5, Nb, Ti, and KCl or In by solid-state reactions at 750°C. Their structure was determined using single-crystal X-ray diffraction; Crystal data: trigonal, P 3 ̄ ml (No. 164) (for K: a=16.8303(11) Å, c=9.0510(8) Å, V=2220.3(3) Å 3 and Z=1; for In: a=16.889(2) Å, c=9.0684(2) Å, V=2240.0(6) Å 3 and Z=1). The full-matrix least-squares refinement of all data against F 2 converged to R 1=0.044, w R 2=0.088 for K, and R 1=0.050, w R 2=0.140 for In. The structure consists of octahedral (Nb 6C1 8 iO 4 i)C1 6 a cluster units that share four outer chloride ligands with four adjacent clusters to form a two-dimensional framework that generates six- and three-member rings similar to those found in hexagonal tungsten bronze. Additional linkages within the same layer are provided by Ti 3Cl 7O 6 trimers. Adjacent layers are stacked in registry with each other leading to the formation of six-member ring openings channels parallel to the [001] direction in which a disordered [ A 5(Ti 2Cl 9)] 2+ species are located. Magnetic susceptibility studies show paramagnetic behavior with a magnetic moment of 3.74 μ B per formula unit.