Ekaterina V. Anokhina

Ti2Nb6Cl14O4: A Unique 2D–1D Network Combination in Niobium Cluster Chemistry

Layers of niobium clusters that are linked to each other through zigzag chains of edge-sharing [TiCl4 O2 ] ocatahedra are the central structural features of the title compound. Bridging of the chains by [(Nb6 Cl8i O4i )Cl6a ]6- clusters results in the formation of empty tunnels (a section of the structure is shown on the right).

Preparation, structure, and properties of a series of anisotropic oxychloride cluster compounds AxNb6Cl12O2 (A=K, Rb, Cs, or In)

Abstract In the course of our investigation aimed at the preparation of anisotropic cluster materials using a combination of oxide and chloride ligands to induce directional bonding preferences in the cluster unit, a series of niobium oxychloride cluster compounds AxNb6Cl12O2 (A=K, x=0.72(2); A=Rb, x=0.736(7); A=Cs, x=0.938(4); A=In, x=0.634(8)) was obtained by solid state synthesis. The cluster framework is based on (Nb6Cl10iO2i)Cl4aO2a clusters connected via oxide ligands in the a → direction with two Nb–O linkages between adjacent clusters, which resembles intercluster bonding in Chevrel–Sergent phases, while in the other two directions, the linkages occur through single Cla–a bridges. The framework generates channels where the cations A+ are located. The electronic band structure of the series features a narrow partially occupied band originating from a Nb–Nb bonding state. Magnetic and ESR measurements show the presence of localized unpaired electrons, and resistivity measurements indicate a semiconducting behavior.

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

New niobium oxychloride cluster compounds corresponding to the general formula, A 5 Ti 8 Nb 18 Cl 53 O 12 (A = K, In), have been prepared in sealed quartz tubes from a mixture containing NbCl 5 , Nh 2 O 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, P3m1 (No. 164) (for K: a = 16.8303(11) A, c = 9.0510(8) A, V = 2220.3(3) A 3 and Z = 1; for In: a = 16.889(2) A, c = = 9.0684(2) A, V = 2240.0(6) A 3 and Z = 1). The full-matrix least-squares refinement of all data against F 2 converged to R 1 = 0.044, wR 2 = 0.088 for K, and R 1 = 0.050, wR 2 = 0.140 for In. The structure consists of octahedral (Nb 5 Cl i 8 O i 4 )Cl a 6 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 3 Cl 7 O 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 2 Cl 9 )] 2+ species are located. Magnetic susceptibility studies show paramagnetic behavior with a magnetic moment of 3.74 μR per formula unit.

A new layered niobium oxochloride cluster compound with novel framework topology

The asymmetric arrangement of chloride and oxide ligands around the octahedral Nb6 cluster core and their electrostatic interaction with Ti3+ counterions play an important role in the formation of a novel 2D framework with cluster connectivity unprecedented in compounds containing octahedral clusters.