Iodido{4-phenyl-1-[1-(1,3-thia­zol-2-yl-κN)ethyl­idene]thio­semicarbazidato-κ2 N′,S}{4-phenyl-1-[1-(1,3-thia­zol-2-yl)ethyl­idene]thio­semicarbazide-κS}mercury(II)

Samuel S R Dasary; Sri Ranjini Arumugam; Hongtao Yu; Ramaiyer Venkatraman; Frank R Fronczek

doi:10.1107/S160053681101974X

. 2011 May 28;67(Pt 6):m816–m817. doi: 10.1107/S160053681101974X

Iodido{4-phenyl-1-[1-(1,3-thiazol-2-yl-κN)ethylidene]thiosemicarbazidato-κ² N′,S}{4-phenyl-1-[1-(1,3-thiazol-2-yl)ethylidene]thiosemicarbazide-κS}mercury(II)

Samuel S R Dasary ^a, Sri Ranjini Arumugam ^a, Hongtao Yu ^a, Ramaiyer Venkatraman ^a, Frank R Fronczek ^b,^*

PMCID: PMC3120629 PMID: 21754688

Abstract

In the title compound, [Hg(C₁₂H₁₁N₄S₂)I(C₁₂H₁₂N₄S₂)], the Hg atom is in a distorted square-pyramidal coordination, defined by the iodide ligand, by the S atom of the neutral ligand in the apical position, and by the N atom of the thiazole ring, the thioureido N and the S atom of the deprotonated ligand. The deprotonated ligand intramolecularly hydrogen bonds to the thiazole ring N atom, while the deprotonated ligand forms an intermolecular hydrogen bond to the thiolate S atom. The deprotonation of the tridentate ligand and its coordination to Hg via the S atom strikingly affects the C—S bond lengths. In the free ligand, the C—S bond distance is 1.685 (7) Å, whereas it is 1.749 (7) Å in the deprotonated ligand. Similarly, the Hg—S bond distance is slightly longer to the neutral ligand [2.6682 (18) Å] than to the deprotonated ligand [2.5202 (19) Å]. The Hg—I distance is 2.7505 (8) Å.

Related literature

For general background to thiosemicarbazones and their Hg complexes, see: Akinchan et al. (2002 ▶); Ali & Livingstone (1974 ▶); Bermejo et al. (1999 ▶, 2003 ▶); Lobana et al. (1998 ▶); Venkatraman et al. (2009 ▶); Blanz & French (1968 ▶); Campbell (1975 ▶); Casas et al. (2000 ▶); Grecu & Neamtu (1967 ▶); Pellerito & Negy (2002 ▶); Raper (1985 ▶).

Experimental

Crystal data

[Hg(C₁₂H₁₁N₄S₂)I(C₁₂H₁₂N₄S₂)]
M _r = 879.23
Triclinic,
a = 8.694 (2) Å
b = 10.119 (2) Å
c = 16.801 (4) Å
α = 76.670 (13)°
β = 79.448 (12)°
γ = 77.190 (13)°
V = 1388.8 (5) Å³
Z = 2
Mo Kα radiation
μ = 6.99 mm⁻¹
T = 90 K
0.10 × 0.10 × 0.03 mm

Data collection

Nonius KappaCCD diffractometer with an Oxford Cryosystems Cryostream cooler
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997 ▶) T _min = 0.542, T _max = 0.818
21861 measured reflections
5837 independent reflections
4289 reflections with I > 2σ(I)
R _int = 0.059

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.085
S = 1.02
5837 reflections
346 parameters
H-atom parameters constrained
Δρ_max = 1.36 e Å⁻³
Δρ_min = −1.27 e Å⁻³

Data collection: COLLECT (Nonius, 2000 ▶); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO (Otwinowski & Minor, 1997 ▶) and SCALEPACK; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053681101974X/vm2089sup1.cif

e-67-0m816-sup1.cif^{(25.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053681101974X/vm2089Isup2.hkl

e-67-0m816-Isup2.hkl^{(279.9KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N7—H7N⋯N5	0.88	1.97	2.667 (8)	135
N4—H4N⋯S2ⁱ	0.88	2.69	3.553 (6)	167

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Symmetry code: (i) Inline graphic .

Acknowledgments

Purchase of the diffractometer was made possible by grant No. LEQSF (1999–2000)-ENH-TR-13, administered by the Louisiana Board of Regents. RV acknowledges the JSU Department of Chemistry and Biochemistry for the supplies and utilization of lab facilities.

supplementary crystallographic information

Comment

Studies on thiosemicarbazones and their metal complexes has remained a fertile field of research for more than three decades due to their significant impacts in biology and chemistry (Ali & Livingstone, 1974; Campbell, 1975; Pellerito & Negy, 2002). Thiosemicarbazones are known to coordinate to many metals, potentially as tridentate ligands. The ligation can occur with the metals as a neutral molecule or, after deprotonation, as an anionic ligand (Campbell, 1975; Raper, 1985; Casas et al., 2000). Further, the metal-chelating ability is attributed to the thione-thiol tautomerism exhibited by these molecules. Some of the metal complexes are found to exhibit enhanced biological activity compared to their basic ligand (Blanz & French, 1968). Among the metals studied with thiosemicarbazones, mercury and organomercury compounds are scarce (Grecu & Neamtu, 1967; Lobana et al.,1998; Bermejo et al., 1999; Akinchan et al., 2002; Bermejo et al., 2003). Removal and remediation of many mercury species from environmental samples are very important. We report here the synthesis and structure of a mercury(II) iodide complex of the phenyl derivative of 2-acetylthiazole-3-thiosemicarbazone. The title complex is a result of interaction between two neutral ligand molecules and mercury(II) iodide in methanol. In this complex, Hg(II) is chelated by two 2-acetylthiazole-3-phenylthiosemicarbazone ligands, forming a distorted square pyramidal geometry (Fig 1). One of the two ligands is deprotonated at N3, and tridentate through its N, N, S atoms. Along with the iodide atom, it forms the square planar base. The other ligand is neutral and apical to the Hg atom, binding through its S atom. The proton NMR also provides the evidence of ligand deprotonation during metal chelation. The sharp resonance signal due to N—NH proton at 11.12 p.p.m. disappears in the spectrum of the complex. The N4 signal (at ~8.64 p.p.m.) in the ligand undergoes a downfield shift that is marked in the mercury (II) complexes, indicating coordination via the S atom. The protonated and deprotonated ligands have different conformations, differing primarily by the N–N–C–N torsion angle, which is antiperiplanar in the deprotonated ligand (torsion angle N2—N3—C6—N4 179.6 (5)°) and synperiplanar in the neutral ligand (torsion angle N6—N7—C18—N8 9.3 (9)°). Hydrogen bonding details are given in Table 1.

Experimental

To a solution of 2-acetyl thiazole thiosemicarbazone (Venkatraman et al. 2009) (1.38 g, 5 mmol) in warm methanol (50 ml) was added an equimolar methanol solution (50 ml) of mercury(II) iodide (1.36 g. 5 mmol). The mixture was stirred for about 24 h, after which time the yellow solid obtained was filtered and vacuum dried (yield ~75%). Crystals suitable for diffraction studies were obtained from the mother liquor at room temperature after a week.