Synthesis and Crystal Structure of A Pyrithione Derivative: Bis{2-[(1-oxidopyridin-2-yl)sulfanyl]-4,5-dihydro-1H-imidazol-3-ium} tetrachlorocuprate(2-)

The pyrithione derivative, bis{2-[(1-oxidopyridin-2-yl)sulfanyl]-4,5-dihydro-1H-imidazol-3-ium} tetrachlorocuprate(2-) (1a) has been obtained by the reaction of one equivalent of 2-[(4,5-dihydro-1H-imidazol-2-yl)thio]pyridine 1-oxide hydrochloride with one and a half equivalents of copper (II) chloride dihydrate in methanol in a very good yield. The structure of this product was confirmed by X-ray crystallography, infrared spectroscopy, and elemental analysis.

For the preparation of 2-[(4,5-dihydro-1H-imidazol-2-yl)thio]pyridine 1-oxide (as free base or acid addition salt), 2-bromopyridine 1-oxide was reacted with an imidazolidine-2-thione in a halogenated hydrocarbon solvent (chloroform) or in ethanol.According to the literature's data, the mixture required heating for 12 hours to give acid addition salt (hydrobromide).The free base may be obtained in dioxane by treatment with an equivalent of dimethylaniline [13,14].

General Methods and Physical Measurements
All reagents and solvents were purchased from commercial sources and used without further purification.The IR spectra were recorded on a Nicolet 380FT-IR spectrophotometer.The 1 H NMR spectrum of compound 1 was registered at 20-22 °C on Varian Gemini 200 ( 1 H = 200 MHz), using the signal of DMSO-d6 as an internal standard.The values of chemical shifts are given in ppm and coupling constants (J) are expressed in hertz (Hz).Measured C, H, N elemental analyzes were within 0.40% of calculated values.The diffraction data for single crystals of 1a were collected with an Oxford Diffraction XcaliburE diffractometer using Mo Kα radiation.The intensity data were collected and processed using CrysAlisPro Software [19].The structure was solved by direct methods with the program SHELXS-97 [20] and refined by the full-matrix least-squares method on F 2 with SHELXL-2018 [21].All H atoms were refined as riding on their carriers.

General Methods and Physical Measurements
All reagents and solvents were purchased from commercial sources and used without further purification.The IR spectra were recorded on a Nicolet 380FT-IR spectrophotometer.The 1 H NMR spectrum of compound 1 was registered at 20-22 • C on Varian Gemini 200 ( 1 H = 200 MHz), using the signal of DMSO-d 6 as an internal standard.The values of chemical shifts are given in ppm and coupling constants (J) are expressed in hertz (Hz).Measured C, H, N elemental analyzes were within 0.40% of calculated values.The diffraction data for single crystals of 1a were collected with an Oxford Diffraction XcaliburE diffractometer using Mo Kα radiation.The intensity data were collected and processed using CrysAlisPro Software [19].The structure was solved by direct methods with the program SHELXS-97 [20] and refined by the full-matrix least-squares method on F 2 with SHELXL-2018 [21].All H atoms were refined as riding on their carriers.

Figure 1 .
Figure 1.(a) ORTEP [18] representation of the molecular structure of 1a.Displacement ellipsoids are shown at the 50% probability level; 'i' relates to symmetry generated atoms.(b) Crystal packing viewed along the b axis with hydrogen bonds shown as dashed lines.Chains of hydrogen-bonded ionic species are extended along [1 0 1].

Figure 1 .
Figure 1.(a) ORTEP [18] representation of the molecular structure of 1a.Displacement ellipsoids are shown at the 50% probability level; 'i' relates to symmetry generated atoms.(b) Crystal packing viewed along the b axis with hydrogen bonds shown as dashed lines.Chains of hydrogen-bonded ionic species are extended along [1 0 1].