Comment

The structure of the title compound, (I), is shown in Fig. 1. Organomercurials are often used as transmetallation reagents in the synthesis of organometallic complexes (Roper & Wright, 1977). Several years ago we reported a synthetic route for the preparation of a range of functionalized 1-mercurio-2-phenyliminophenyls (Flower et al., 2002) and from the structural data obtained concurred with a previous report of Batsanov (1998) that the van der Waals radius of mercury is in the range 2.0-2.2 Å, rather than the often quoted value of 1.55 Å (Bondi, 1964). Here, and in the following paper (Flower & Pritchard, 2006), we report two additional structures of this type of compound. All of the bond lengths and angles in the two structures are as expected. The Hg-N distances in (I) and bis-2-(2-isopropylphenylimnophenyl)mercury, (II), range from 2.787 (10) to 2.850 (10) Å and are comfortably within the sum of the van der Waals radii (3.5-3.7 Å), if the van der Waals radius of Hg is considered to be 2.0-2.2 Å, indicating significant Hg-N interactions. This gives rise to an overall distorted square-planar geometry at Hg in both cases. Other examples of square planar Hg^II complexes are known (Balasubramani et al., 2005; Haid et al., 2003; Cheng et al., 1994).

Figure 1 The molecular structure of (I), showing the atomic numbering scheme. Displacement ellipsoids are shown at the 30% probability level.

Experimental

Caution: preparation of an organomercurial. Organomercurials are extremely toxic. To Hg(C₆H₄-2-CHO)₂ (1 g, 2.4 mmol) dissolved in ethanol (10 ml) containing p-toluenesulfonic acid (10 mg, 0.05 mmol) was added 2-methylaniline (0.56 g, 6 mmol) and the solution was refluxed for 5 h, during which time white crystals of (I) precipitated. The crystalline material was collected by filtration, washed with water and dried in a desiccator. Yield 0.93 g, 68%. An analytically pure sample was obtained through recrystallization from hot ethanol, and crystals suitable for the diffraction study were grown by dissolving approximately 10 mg of (I) in CH₂Cl₂ (0.2 ml) in a small vial (1 × 5 cm), layering ethanol (5 ml) on top and leaving the vial to to stand for 24 h. Elemental analysis C₂₈H₂₄HgN₂ requires: C 57.56, H 4.11, N 4.76%; found: C 57.79, H 4.22, N 4.91%.

H atoms were positioned geometrically and treated as riding, with C-H = 0.93 and 0.96 Å, and with U_iso(H) values of 1.2 and 1.5 times U_eq(C). The highest residual peak is located 1.03 Å from Hg1 and deepest hole is located 0.92 Å from Hg1..

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).