Tetrakis(5,7-dimethylquinolin-8-olato-κ2 N,O)zirconium(IV) dimethylformamide disolvate

In the title compound, [Zr(C11H10NO)4]·2C3H7NO, the ZrIV ion is coordinated by four bidentate 5,7-dimethylquinolin-8-olate ligands in a slightly distorted square-antiprismatic coordination environment. The asymmetric unit also contains two N,N′-dimethylformamide (DMF) solvent molecules. In the crystal, a weak C—H⋯O hydrogen bond links the complex molecule to a solvent molecule and weak π–π stacking interactions [centroid–centroid distance = 3.671 (3) Å] also occur. One of the DMF solvent molecules was refined as disordered over three sets of sites, with refined occupancies in the ratio of 0.391 (9):0.342 (10):0.267 (7).

In the title compound, [Zr(C 11 H 10 NO) 4 ]Á2C 3 H 7 NO, the Zr IV ion is coordinated by four bidentate 5,7-dimethylquinolin-8olate ligands in a slightly distorted square-antiprismatic coordination environment. The asymmetric unit also contains two N,N 0 -dimethylformamide (DMF) solvent molecules. In the crystal, a weak C-HÁ Á ÁO hydrogen bond links the complex molecule to a solvent molecule and weakstacking interactions [centroid-centroid distance = 3.671 (3) Å ] also occur. One of the DMF solvent molecules was refined as disordered over three sets of sites, with refined occupancies in the ratio of 0.391 (9):0.342 (10):0.267 (7).

Experimental
Chemicals were purchased from Sigma-Aldrich and used as received. ZrCl 4 (101.3 mg, 0.435 mmol) and 5,7-Dimethyl-8quinolinol (diMeOxH) (228.2 mg, 1.317 mmol) was separately dissolved in DMF (2.5 ml ea) and heated to 60°C. The diMeOxH solution as added drop-wise to the zirconium solution and stirred at 333 K for 30 minutes. The reaction solution was removed from heating, covered and left to stand. Red cuboid crystals, suitable for single X-Ray diffraction, formed after 10 days. (Yield: 203 mg, 79%).

Refinement
H atoms were placed inidealized positions (C-H = 0.93-0.96Å) and constrained to ride on their parent atoms with U iso (H) = 1.2-1.5U eq (C). The highest residual electron density was located 0.95 Å from O102. One of the DMF solvent molecules was refined as disordered over three sets of sites with refined occupancies in a ratio of 0.391 (9):0.342 (10):0.267 (7).

Figure 1
The molecular structre of the Zr complex of the title compound. Displacement ellipsoids are drawn at the 50% probability level. H atoms and the solvent molecules are omitted for clarity.  Part of the crystal structure with weak π-π interactions shown as dashed lines.

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.