(2-{[4-(Chloridomercuryl)phenyl]iminomethyl}pyridine-κ2 N,N′)diiodidomercury(II) dimethyl sulfoxide monosolvate

The title dimethyl sulfoxide solvate, [Hg2(C12H9ClN2)I2]·C2H6OS, features tetrahedrally and linearly coordinated HgII atoms. The distorted tetrahedral coordination sphere is defined by chelating N atoms that define an acute angle [69.6 (3)°] and two I atoms that form a wide angle [142.80 (4)°]. The linearly coordinated HgII atom [177.0 (4)°] exists with a donor set defined by C and Cl atoms. Secondary interactions are apparent in the crystal packing with the tetrahedrally and linearly coordinated HgII atoms expanding their coordination environments by forming weak Hg⋯I [3.772 (7) Å] and Hg⋯O [2.921 (12) Å] interactions, respectively. Mercury-containing molecules stack along the a axis, are connected by π–π interactions [inter-centroid distance between pyridine and benzene rings = 3.772 (7) Å] and define channels in which the dimethyl sulfoxide molecules reside. The latter are connected by the aforementioned Hg⋯O interactions as well as C—H⋯I and C—H⋯O interactions, resulting in a three-dimensional architecture.

The title dimethyl sulfoxide solvate, [Hg 2 (C 12 H 9 ClN 2 )I 2 ]Á-C 2 H 6 OS, features tetrahedrally and linearly coordinated Hg II atoms. The distorted tetrahedral coordination sphere is defined by chelating N atoms that define an acute angle [69.6 (3) ] and two I atoms that form a wide angle [142.80 (4) ]. The linearly coordinated Hg II atom [177.0 (4) ] exists with a donor set defined by C and Cl atoms. Secondary interactions are apparent in the crystal packing with the tetrahedrally and linearly coordinated Hg II atoms expanding their coordination environments by forming weak HgÁ Á ÁI [3.772 (7) Å ] and HgÁ Á ÁO [2.921 (12) Å ] interactions, respectively. Mercury-containing molecules stack along the a axis, are connected byinteractions [inter-centroid distance between pyridine and benzene rings = 3.772 (7) Å ] and define channels in which the dimethyl sulfoxide molecules reside. The latter are connected by the aforementioned HgÁ Á ÁO interactions as well as C-HÁ Á ÁI and C-HÁ Á ÁO interactions, resulting in a three-dimensional architecture.     (2) Å out of the plane of the remaining four atoms (r.m.s. deviation = 0.0022 Å). In terms of angles, the major distortions from the ideal tetrahedral geometry about the Hg1 atom is found in the acute chelate angle (69.6 (3)°) and the wide angle subtended by the large I atoms (142.80 (4)°). The benzene ring carrying the HgCl atoms is almost co-planar to the pyridyl ring, forming a dihedral angle of 6.5 (6)°. The geometry about the Hg2 atom is linear as expected (177.0 (4)°).

Refinement
Carbon-bound H-atoms were placed in calculated positions [C-H = 0.93 to 0.96 Å, U iso (H) 1.2 to 1.5U eq (C)] and were included in the refinement in the riding model approximation. The maximum and minimum residual electron density peaks of 4.39 and 1.45 e Å -3 , respectively, were located 0.99 and 0.80 Å from the Hg1 atom.

Figure 1
Molecular structure of (I) showing atom-labelling scheme and displacement ellipsoids at the 50% probability level.

Figure 2
A view of the unit-cell contents in projection down the a axis in (I). The Hg···I, O secondary interactions are shown as pink and black dashed lines, respectively. The π-π, C-H···I and C-H···O interactions are shown as purple, green and orange dashed lines, respectively.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 > 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.