Dichlorido(4-{[(quinolin-2-yl)methylidene]amino}phenol-κ2 N,N′)mercury(II)

In the mononuclear title complex, [HgCl2(C16H12N2O)], synthesized from the phenolic Schiff base 4-[(quinolin-2-ylmethylidene)amino]phenol (QMAP), the coordination geometry around Hg2+ is distorted tetrahedral, comprising two Cl atoms [Hg—Cl = 2.3565 (12) and 2.5219 (12) Å] and two N-atom donors from the QMAP ligand, viz. one imine and the other quinoline [Hg—N = 2.392 (2) and 2.237 (2) Å, respectively]. In the crystal, O—H⋯Cl hydrogen bonds generate a chain structure extending along the c-axis direction. Weak C—H⋯Cl and π–π stacking interactions [minimum ring centroid separation = 3.641 (3) Å] give an overall layered structure lying parallel to (001).


Comment
Quinoline derivatives of Schiff bases are important building blocks of many important compounds widely used in biological applications such as antioxidative and anticancer and fluorescent probe agents in industry and in coordination chemistry (Das et al., 2013;Jursic et al., 2002). The synthesis of polymeric complex of mercury(II) using the quinoline aldehyde derivative of the Schiff base 4-(quinolin-2-ylmethylene)aminophenol (QMAP) has not previously been reported. The title Hg II complex with QMAP, [Hg(C 16 H 12 N 2 O)Cl 2 ] has been synthesized and the structure is reported herein.
In the title mononuclear complex (  (Table 2) give a one-dimensional chain structure which extends along c (Fig. 2) and weak C7-H···Cl2 hydrogen bonds and π-π ring stacking interactions [minimum ring centroid separation between the inversion related benzene and quinoline rings = 3.641 (3) Å] give an overall two-dimensional layered structure lying parallel to (001) (Fig. 3).

Experimental
A mixture of 4-(quinolin-2-ylmethylene)aminophenol (QMAP) (0.10 g, 0.40 mmol), mercury(II) chloride (0.11 g, 0.40 mmol) and ethanol (5 ml) were stirred vigorously for 30 min, after which the precipitate was filtered off and dissolved in dimethylformamide. Crystals of the title complex suitable for X-ray analysis was obtained within 2 days by slow evaporation of the DMF solvent.

Refinement
All H-atoms were positioned geometrically and refined using a riding model with C-H = 0.92-0.93 Å and U iso (H) = 1.2U eq (C). The phenolic H-atom as located from a difference-Fourier map was also allowed to ride, with O-H = 0.83 (2) Å and, U iso (H) = 1.5U eq (O).  The molecular conformation and atom-numbering scheme for the title complex with non-H atoms drawn as 30% probability displacement ellipsoids.

Figure 2
The one-dimensional hydrogen-bonded chain structure in the title complex extending along c, with hydrogen bonds shown as dashed lines.  The two-dimensional structure viewed along the a-axial direction.

Dichlorido(4-{[(quinolin-2-yl)methylidene]amino}phenol-κ 2 N,N′)mercury(II)
Crystal data [HgCl 2 (C 16  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 > σ(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq C1 0.7674 (4