Diiodido(1,10-phenanthroline-5,6-dione-κ2 N,N′)mercury(II)

The HgII atom in the title complex, [HgI2(C12H6N2O2)], is tetrahedrally coordinated by the N atoms of the chelating 1,10-phenanthroline-5,6-dione ligand and two I atoms. The range of tetrahedral angles is broad, viz. 68.94 (17)° for the chelate angle to a wide 132.627 (15)° for the I—Hg—I angle. The ligand molecule is non-planar with the O atoms lying 0.422 (5) and −0.325 (5) Å out of the plane through the remaining atoms [r.m.s. deviation = 0.068 Å]. Molecules are consolidated in the crystal packing by C—H⋯O interactions.


Related literature
For the ligand synthesis and the crystal structure of 1,10phenanthroline-5,6-dione, see: Calderazzo et al. (1999). For an evaluation of the different coordinating ability of the two sets of donor atoms in the ligand, see: Fujihara et al. (2003). For the structure of the dichlorido analogue with two 1,10-phenanthroline-5,6-dione ligands, see: Figueiras et al. (2009). For the crystallization procedure, see: Harrowfield et al. (1996).
We acknowledge financial support of this work by the Islamic Azad University, Saveh Branch, and thank the University of Malaya for support of the crystallographic facility.
The Hg atom in (I), Fig. 1 and Table 1, is chelated by the 1,10-phenanthroline-5,6-dione ligand and the distorted tetrahedral I 2 N 2 donor set is completed by two I atoms. The range of tetrahedral angles is from a narrow 68.94 (17)°, for the chelate angle, to a wide 132.627 (15)°, for the angle subtended at Hg by the I atoms. The 1,10-phenanthroline-5,6-dione ligand is planar with the r.m.s. deviation for the 14 C and N atoms being 0.068 Å with the maximum deviations from the least-squares plane being 0.146 (6) Å for atom C7 and -0.116 (7) for atom C6; the O1 and O2 atoms lie -0.325 (5) and 0.422 (5) Å out of this plane, respectively.
The molecules of (I) are consolidated in the crystal packing via weak C-H···O interactions involving both O atoms, Table 2 and Fig. 2.

Experimental
The title complex was obtained by the branched tube method (Harrowfield et al., 1996). 1,10-Phenanthroline-5,6-dione (0.136 g, 0.648 mmol) and HgI 2 (0.294 g, 0648 mmol) were placed at the bottom of main arm of a branched tube. Methanol was carefully added to fill both arms. The tube was sealed and the main arm immersed in a bath at 333 K while the other was kept at ambient temperature. After five days, red crystals were deposited in the cooler arm. These were filtered off,
supplementary materials sup-2 Figures   Fig. 1. The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 70% probability level. Diiodido(1,10-phenanthroline-5,6-dione-κ 2 N,N')mercury (II) Crystal data [HgI 2 (C 12  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 Rfactors(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