cis-Dioxido[N′-(2-oxidobenzylidene)pyridinium-4-carbohydrazidato-κ3 O,N′,O′]vanadium(V)

The title Schiff base complex, [V(C13H10N3O2)O2], features a square-pyramidal coordination geometry defined by the O,N′,O′-donors of the tridentate Schiff base ligand and two oxide O atoms; one oxide O atom occupies the apical position. In the crystal, pyridinium–oxide N—H⋯O hydrogen bonds lead to zigzag supramolecular chains with a flattened topology along [101]. The investigated crystal was twinned by nonmerohedry; the minor component refined to 18.5 (5)%.

The title Schiff base complex, [V(C 13  In the crystal, pyridinium-oxide N-HÁ Á ÁO hydrogen bonds lead to zigzag supramolecular chains with a flattened topology along [101]. The investigated crystal was twinned by nonmerohedry; the minor component refined to 18.5 (5)%.

Gholam Hossein Shahverdizadeh, Seik Weng Ng, Edward R. T. Tiekink and Babak Mirtamizdoust Comment
In continuation of structural studies of vanadyl Schiff base complexes (Shahverdizadeh et al., 2012), the title complex, donor set is based on a square pyramid with oxido-O3 atom in the axial position. The coordination geometry is quantified by the calculation of τ = 0.05 which compares with τ = 0.0 for an ideal square pyramidal geometry and τ = 1.0 for an ideal trigonal bipyramid (Addison et al., 1984). The V═O3 bond length is significantly shorter than the V═O4 bond length, Table 1, an observation ascribed to the influence exerted by the trans-N1 atom and the participation of the oxido O4 atom in hydrogen bonding, Table 2. The pyridinium-NH···O(oxido) hydrogen bonding leads to a zigzag chain along [101] with a flattened topology.
The Schiff base ligand in (I) is present as a pyridinium cation. A precedent exists in the literature in a closely related V complex (Yu et al., 2007).

Experimental
A solution of salicylaldehyde (10 mmol) in EtOH (25 ml) was added drop-wise to the solution of 4-pyridinecarboxylic acid hydrazide (10 mmol) in EtOH (15 ml). The mixture was refluxed for 8 h. The yellow precipitate was removed by filtration and recrystallized from MeOH solution. The product (0.5 mmol) was placed in one arm of a branched tube (Harrowfield et al., 1996) and vanadium(IV) oxide acetylacetonate (0.5 mmol) in the other. Methanol was then added to fill both arms, the tube sealed and the ligand-containing arm immersed in a bath at 333 K, while the other was left at ambient temperature. After 8 d, crystals had deposited in the arm held at ambient temperature. These filtered off, washed with acetone and ether, and air-dried. Yield: 72%. M.pt. 566 K.

Refinement
The crystal was a non-merohedral twin. The twin components were separated by the TwinRotMat routine in PLATON (Spek, 2009); the minor component refined to 18.5 (5)%. Carbon-bound H-atoms were placed in calculated positions [C -H 0.95 Å, U iso (H) 1.2U eq (C)] and were included in the refinement in the riding model approximation. The pyridinium H-atom was located in a difference Fourier map and was refined with a distance restraint of N-H 0.88±0.01 Å with U iso (H) 1.2U eq (N). The maximum and minimum residual electron density peaks of 1.36 and 0.84 e Å -3 , respectively, were located 0.91 Å and 0.65 Å from the V atom, respectively. Owing to poor agreement, the reflection (4 8 11) was omitted from the final refinement.

Figure 1
The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 70% probability level.

cis-Dioxido[N′-(2-oxidobenzylidene)pyridinium-4-carbohydrazidato-κ 3 O,N′,O′]vanadium(V)
Crystal data [V(C 13  Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.