Crystal structure of chloronitrato-2-{2′-[(1′-methyl)benzimidazolyl]}- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxidemercury(II) – mercury(II)chloride, HgCl(NO3)(C15H19N4O2) · HgCl2

C15H19Cl3Hg2N5O5, triclinic, P1 (no. 2), a = 9.922(2) Å, b = 10.822(2) Å, c = 11.460(2) Å, * = 107.518(2)°, ) = 102.046(2)°, & = 96.639(2)°, V = 1126.5 Å, Z = 2, Rgt(F) = 0.026, wRref(F) = 0.065, T = 294 K. Source of material The nitroxide NIT-1'-MeBzIm (NIT-1'-MeBzIm = 2-{2'-[(l'methyl)benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1oxyl-3-oxide) was prepared by the literature method [1]. To a mixed solution of Hg(NO3)2 (0.2 mmol) and HgCl2 (0.2 mmol) in ethanol (10 mL) was added with stirring a solution of the NIT-1'MeBzIm (0.2 mmol ) in ethanol (10 mL). The mixture was stirred for further two hours affording a color change from dark purple to dark black, then the reaction mixture was filtered. The filtrate was kept in ether vapor at room temperature by slow diffusion of ether into the ethanol solution of the complex. Black block-shaped single crystal were obtained. Discussion During the past decade, nitronyl nitroxide radicals (NITR) have been widely employed as molecular units in the design and synthesis of molecular magnetic materials [2-4], due to their exceptional stability and their rich chemistry. A lot of studies on the magnetic properties of the nitronyl nitroxide and imino nitroxide radicals of metal complexes have been reported [5-7]. In many different types of organic radicals, research was focused on the nitronyl nitroxide radicals (NITR) family because of their flexibility and functionality. Some diamagnetic metal complexes with organic radicals as a ligand, however, have shown ferro or antiferromagnetic interactions operated through the diamagnetic metal ions. The title crystal structure consists of a Hg(NIT-1 'MeBzIm)(NO3)(Cl) molecule and a HgCl2 molecule. The distorted square-pyramidal ion Hg1 is coordinated to a NIT-1'MeBzIm radical ligand, a NO3 anion and a Cl anion. NIT-1'MeBzIm radical ligand acting as bidentate chelating ligand coordinates Hg1 ion through the oxygen atom of NIT-1'-MeBzIm and the nitrogen atom of the benzimidazole ring. Three oxygen atoms and one nitrogen atom from the NIT-1'-MeBzIm and NO3 anion form the equatorial plane. The chlorine atom occupies axial position. The bond lengths of Hg1—O1, Hg1—O4, Hg1—O5 and Hg1—N2 are 2.593(4) Å, 2.595(4) Å, 2.643(5) Å and 2.111(4) Å, respectively. The axial d(Hg—Cl) is 2.292(2) Å. These values correspond well with those in literatures [8,9]. The bond length O1—N3 (1.284(5) Å) of the coordinated segment is a little longer than the free d(O2—N4) = 1.262(6) Å. O1–N3–C9–N4–O2 is nearly co-planar but make a dihedral angle of 41.0(2)° with the plane of the benzimidazole ring. The approximate linear environment of Hg2 atom is formed by the chlorine atoms. The bond lengths of Hg2—Cl2 and Hg2—Cl3 are 2.265(2) Å and 2.278(2) Å, respectively. The bond angle of Cl2–Hg2–Cl3 is 175.58(8)°. There exit intermolecular interactions, via a weak Hg···O bond with d(Hg1—O1) = 2.938 Å, d(Hg2—O4’) = 2.831 Å, d(Hg2—O3’) = 2.871 Å. Therefore, formation of a polymeric chain is achieved through intermolecular interactions. Z. Kristallogr. NCS 226 (2011) 173-174 / DOI 10.1524/ncrs.2011.0079 173 © by Oldenbourg Wissenschaftsverlag, München Crystal: black block, size 0.05 × 0.17 × 0.27 mm Wavelength: Mo K* radiation (0.71073 Å) -: 140.05 cm−1 Diffractometer, scan mode: Bruker SMART CCD, "/% 2+max: 51° N(hkl)measured, N(hkl)unique: 8637, 4162 Criterion for Iobs, N(hkl)gt: Iobs > 2 ((Iobs), 3635 N(param)refined: 276 Programs: SHELXS-97, SHELXS-97 [10] Table 1. Data collection and handling.