Dichloridobis(1,10-phenanthroline-5,6- dione-j 2 N,N 0 )mercury(II) Carlos A. L. Figueiras, a Joa ˜o A. S. Bomfim, a R. Alan Howie, b Edward R. T. Tiekink c * and James L. Wardell d ‡ a Departamento de Quı ´mica Inorga ˆnica, Instituto de Quı ´mica, Universidade Federal do Rio de Janeiro, CP 68563, 21941-909 Rio de Janeiro, RJ, Brazil, b Department of Chemistry, University of Aberdeen, Old Aberdeen, AB15 5NY, Scotland, c Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia, and d Departamento de Quimica, ICEx, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil Correspondence e-mail: edward.tiekink@gmail.com Received 10 November 2009; accepted 18 November 2009 Key indicators: single-crystal X-ray study; T = 120 K; mean (C–C) = 0.012 A ˚ ; R factor = 0.037; wR factor = 0.094; data-to-parameter ratio = 15.6. In the title compound, [HgCl 2 (C 12 H 6 N 2 O 2 ) 2 ], the Hg II atom is located on a twofold rotation axis and exists within a distorted octahedral geometry defined by a cis-Cl 2 N 4 donor set. Molecules are connected into layers in the ac plane via extensive C—HCl contacts as each Cl atom forms two such interactions. Contacts between the layers are of the type C O [Ocentroid distance = 3.110 (8) A ˚ ]. Related literature For related main-group compounds of 1,10-phenanthroline- 5,6-dione, see: de Alencastro et al. (2005). For the ligand synthesis, see: Yamada et al. (1992). For a related structure, see: Ramezanipour et al. (2005). Experimental Crystal data [HgCl 2 (C 12 H 6 N 2 O 2 ) 2 ] M r = 691.87 Orthorhombic, Fdd2 a = 8.2261 (2) A ˚ b = 42.6761 (11) A ˚ c = 12.6108 (3) A ˚ V = 4427.12 (19) A ˚ 3 Z =8 Mo K radiation  = 7.24 mm 1 T = 120 K 0.20  0.10  0.06 mm Data collection Nonius KappaCCD diffractometer Absorption correction: multi-scan (SADABS; Sheldrick, 1996) T min = 0.204, T max = 0.651 10751 measured reflections 2487 independent reflections 2239 reflections with I >2(I) R int = 0.075 Refinement R[F 2 >2(F 2 )] = 0.037 wR(F 2 ) = 0.094 S = 1.05 2487 reflections 159 parameters 1 restraint H-atom parameters constrained Á max = 2.27 e A ˚ 3 Á min = 0.68 e A ˚ 3 Absolute structure: Flack (1983), 1163 Friedel pairs Flack parameter: 0.012 (13) Table 1 Selected bond lengths (A ˚ ). Hg—N1 2.439 (7) Hg—N2 2.512 (6) Hg—Cl1 2.5270 (19) Table 2 Hydrogen-bond geometry (A ˚ ,  ). D—HA D—H HA DA D—HA C2—H2Cl1 i 0.95 2.69 3.578 (8) 156 C9—H9Cl1 ii 0.95 2.78 3.701 (8) 164 Symmetry codes: (i) x  1; y; z; (ii) x þ 1 2 ; y; z  1 2 . Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduc- tion: DENZO and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publi- cation: publCIF (Westrip, 2009). The use of the EPSRC X-ray crystallographic service at the University of Southampton, England, and the valuable assis- tance of the staff there are gratefully acknowledged. JLW acknowledges support from FAPEMIG (Brazil). Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HY2254). References Alencastro, R. B. de, Bomfim, J. A. S., Filgueiras, C. A. L., Howie, R. A. & Wardell, J. L. (2005). Appl. Organomet. Chem. 19, 479–487. Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany. Flack, H. D. (1983). Acta Cryst. A39, 876–881. Hooft, R. W. W. (1998). COLLECT. Nonius BV, Delft, The Netherlands. Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press. Ramezanipour, F., Aghabozorg, H. & Soleimannejad, J. (2005). Acta Cryst. E61, m1194–m1196. Sheldrick, G. M. (1996). SADABS. University of Go ¨ttingen, Germany. Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Westrip, S. P. (2009). publCIF. In preparation. Yamada, M., Tanaka, Y., Yashimoto, Y., Juroda, S. & Shimao, I. (1992). Bull. Chem. Soc. Jpn, 65, 1006–1011. metal-organic compounds Acta Cryst. (2009). E65, m1645 doi:10.1107/S1600536809049289 Figueiras et al. m1645 Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368 ‡ Additional correspondence author, e-mail: j.wardell@abdn.ac.uk.