catena-Poly[2,2′,2′′-nitrilotris(ethanaminium) [tri-μ-oxido-tris[dioxidovanadate(V)]] monohydrate]

The title compound, {(C6H21N4)[V3O9]·H2O}n, crystallizes as a salt with [trenH3]3+ cations [tren is tris(2-aminoethyl)amine], and one-dimensional anionic {[VVO3]−}n (metavanadate) chains along the c-axis direction. Three crystallographically distinct VV sites and one occluded water molecule are present for every [trenH3]3+ cation in the unit cell. The {[VVO3]−}n chains are composed of vertex-sharing [VO4] tetrahedra and have a repeat unit of six tetrahedra. Each tetrahedron in the chain contains two terminal and two μ2-bridging oxide ligands. The [trenH3]3+ cations, {[VVO3]−}n anions and occluded water molecules participate in an extensive three-dimensonal hydrogen-bonding network. The three terminal ammonium sites of the [trenH3]3+ cations each form strong N—H⋯O hydrogen bonds to terminal oxide ligands on the {[VVO3]−}n chain. Each occluded water molecule also donates two O—H⋯O hydrogen bonds to the terminal oxide ligands.


Related literature
For properties of organically templated metal oxides, see: Cheetham et al. (1999). A host of amine-templated metavanadate chains with connectivities identical to the title compound have been reported previously, for examples, see: Riou & Ferey (1996); Roman et al. (1991); Smith et al. (2012). Metavanadate chains with repeat units of six tetrahedra are known to exist, see: Lin et al. (2003); Tyrselová et al. (1995). For details of the H-atom treatment in the refinement, see: Cooper et al. (2010).

Comment
Organically templated metal oxides have been the subject of sustained interest for many years, owing to their structural diversity and potential to exhibit technologically desirable physical properties (Cheetham et al., 1999

Experimental
All chemicals (reagent grade) were commercially available and were used as received. Deionized water was used in this synthesis. The title compound was prepared under mild hydrothermal conditions in a 23 mL Teflon-lined stainless-steel autoclave. V 2 O 5 (0.1449 g, 0.7967 mmol), Na 2 TeO 3 (0.0889 g, 0.4012 mmol), tren (0.0620 g, 0.4240 mmol), ethanol (4 ml, 0.069 mol), and H 2 O (4 ml, 0.22 mol) were mixed to give a reaction mixture with a molar composition ratio of 2:1:1:170:550. The role of Na 2 TeO 3 in this reaction is not understood. Reactions were placed in a 110 °C oven for 5 d.
The reactions were then cooled to room temperature at a rate of 6 °C h -1 to promote the growth of large single crystals.
Reaction vessels were opened in air, and the title compound was recovered as clear colorless needles in the presence of an unidentified tan powder via vacuum filtration.

Refinement
While the H atoms were all located in a difference map, they were repositioned geometrically. The H atoms were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C-H in the range 0.93-0.98, N -H to 0.95, and O-H = 0.95 Å) and U iso (H) (in the range 1.2-1.5 times U eq of the parent atom), after which the positions were refined with riding constraints (Cooper et al., 2010).

Figure 1
The title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as spheres of arbitary radius.

Figure 2
A packing diagram of the title compound, viewed down the c axis. Orange tetrahedra represent [VO 4 ], while red, blue and white spheres represent oxygen, nitrogen, carbon and hydrogen atoms, respectively.