Synthesis and crystal structure of bis(2-aminobenzimidazolium) catena-[metavanadate(V)]

The title compound contains infinite linear zigzag vanadate (V2O6)2−chains, constructed from corner-sharing VO4 tetrahedra, running parallel to the a axis.


Chemical context
In recent years, vanadate compounds have attracted attention in various fields due to their various compositions and interesting structures (Smith et al., 2012;Wutkowski et al., 2009;Wang et al., 2007).This is partly due to the ability of vanadium to adopt tetrahedral [VO 4 ], square-pyramidal [VO 5 ], trigonalbipyramidal [VO 5 ] or octahedral [VO 6 ] coordination environments together with possible stable oxidation states of +III, +IV and +V.Interestingly, all major vanadate compounds known to date containing cage-, shell-, belt-, barrel-, or basketshaped entities are structurally related to the layer structure of vanadium pentoxide (Ishaque Khan et al., 2000).These compounds have many practical pharmacological applications, ranging from anticancer agents to antifungal agents and, more recently, as insulin mimetics (Singh et al., 2014;Abakumova et al., 2012;Amin et al., 2000) where they interact with several points in the cell-signaling pathway associated with the hormone insulin (Amin et al., 2000;Srivastava & Mehdi, 2005).Studies have also indicated that vanadate compounds interact directly with glucose transporters located on the cell surface (Hiromura et al., 2007;Makinen & Brady, 2002).Furthermore, vanadium has been found to have important interactions in DNA repair systems, making it a useful target for many oncological/pharmacological studies (Abakumova et al., 2012;Kostova, 2009).Given the structural dependence on functions and application, a deeper study of the molecular and crystal structures of such complexes is warranted.In this context, we describe the synthesis and structural features of the polymeric title compound {(C 7 H 8 N 3 ) 2 (V 2 O 6 )} n .

Structural commentary
The asymmetric unit comprises two 2-aminobenzimidazolium cations (denoted A and B) and two V and six O atoms of the polymeric metavanadate anion (Fig. 1).The cationic molecules are almost planar (root-mean-square deviation for A = 0.0127 A ˚and for B = 0.0064 A ˚), and their N-C bond-length distributions are similar to those in related compounds (Aliabadi et al., 2021;Ruzieva et al., 2022).The linear zigzag metavanadate (V 2 O 6 ) 2-chain runs parallel to the a axis and is constructed from corner-sharing VO 4 tetrahedra (Fig. 2).Typical for such chains, the bridging O atoms (O3 and O4) have considerably longer V-O bonds than the terminal O atoms (O1 and O2 for the V1O 4 tetrahedron and O5 and O6 for the V2O 4 tetrahedron; Table 1).The corresponding V-O and V O bond lengths are similar to those reported for related hybrid metavanadate compounds (Smith et al., 2012;Wutkowski et al., 2009;Wang et al., 2007;Tyrselova et al., 1996).

Supramolecular features
The crystal packing exhibits an intricate network of classical intermolecular N-H� � �O hydrogen bonds between the NH and NH 2 groups of the cations and all oxygen atoms of the metavanadate chain (Fig. 3, Table 2).Additional short The asymmetric unit of the title compound with the labeling scheme and displacement ellipsoids drawn at the 50% probability level.Dotted lines indicate N-H� � �O hydrogen-bonding interactions.

Synthesis and crystallization
All reagents for synthesis and analysis were commercially available and purchased from Sigma Aldrich and used as received without further purification.Chemically pure vanadyl acetylacetonate, 2-aminobenzimidazole, and 96% vol ethanol were used.Vanadyl acetylacetonate (0.0265 g, 1 mmol) dissolved in 5 ml of EtOH and 2-aminobenzimidazole (0.0133 g, 1 mmol) dissolved in 5 ml of EtOH were mixed with constant stirring until the color of the solution turned to green.The stirring was continued for three hours.The resulting green solution was then allowed to cool to room temperature and green crystals were grown over seven days via slow evaporation of the mother liquor.Selected IR bands (KBr pellet,    (Rigaku OD, 2020), SHELXT (Sheldrick, 2015a), SHELXL (Sheldrick, 2015b), Mercury (Macrae et al., 2020), PLATON (Spek, 2020) and publCIF (Westrip, 2010).

Refinement
Crystal data, data collection and structure refinement details are summarized in Synthesis and crystal structure of bis(2-aminobenzimidazolium)

Special details
Geometry.All esds (except the esd in the dihedral angle between two l.s.planes) are estimated using the full covariance matrix.The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry.An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s.planes.

Figure 3
Figure 3View of the crystal structure of the title compound along the a axis, showing N-H� � �O hydrogen bonds drawn as blue dotted lines.

Figure 4
Figure4V2-O6� � �Cg4 interactions in the crystal structure of the title compound.

Table 3
Experimental details.
Computer programs: CrysAlis PRO