Acta Cryst. (2006). E62, m175-m178  [ doi:10.1107/S1600536805040171 ]

Hexaaquadodeca--chloro-hexaniobium(II,III) dichloride 2,2'-bipyridine trisolvate

M. S. Tarasenko, A. V. Virovets, N. G. Naumov and V. E. Fedorov

Abstract: The title compound, [Nb₆Cl₁₂(H₂O)₆]Cl₂·3C₁₀H₈N₂, is an example of a `hybrid' inorganic-organic compound, where the inorganic and organic parts do not interact by covalent bonds but are joined by hydrogen bonding. The inorganic part contains a hexanuclear mixed-valence niobium cluster aqua cation [Nb₆(-Cl)₁₂(H₂O)₆]²⁺, with the typical {M₆X₁₂} structure, and two Cl^- counter-ions. The organic part consists of two crystallographically independent 2,2'-bipyridine molecules; one is planar and lies on a centre of symmetry, and the other is twisted by 42.1 (5)°. The Nb-Nb, Nb-Cl and Nb-O bond distances are close to those found in other salts of this cation. The inorganic and organic parts are joined together by an extended system of hydrogen bonds. Six of the 12 H atoms of the aqua ligands form hydrogen bonds with the N atoms of the bipyridine molecules, and the other six with Cl^- anions. At the same time, the bipyridine molecules use both N atoms in hydrogen bonding with two cluster cations. Each Cl^- anion forms three ClH-O bonds with the three cluster cations. The resulting three-dimensional framework shows a non-trivial example of a (12,3,2,2) connected net. The disposition and relative orientation of the cluster cations and the geometric requirements of the hydrogen-bonds dictate the conformations of the bipyridine molecules.

Online 23 December 2005

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