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SYNTHESIS AND STRUCTURE OF MIXED LIGAND ZN(II) METAL
COMPLEX ON THE BASE OF 2-AMINO 5-METHYLTHIO-1,3,4-
THIODIAZOLE
Safarov A.R.
Bozorov I.A.
Obidjonova V.R.
Sadullayeva G.B.
Ibragimov A. B.
Institute of General and Inorganic Chemistry, Academy of Sciences of
Uzbekistan, 77a Mirzo Ulugbek Street, Tashkent 100170, Uzbekistan
https://doi.org/10.5281/zenodo.15797077
In this study, we report the synthesis and structural investigation of a novel
mixed-ligand Zn(II) coordination complex based on 2-amino-5-methylthio-1,3,4-
thiadiazole (AMTT) and a carboxylate-type co-ligand (e.g., acetate). The complex
was obtained via a straightforward reflux method, where Zn(II) salt was reacted
with AMTT and the carboxylate ligand in ethanol-water mixture under
controlled stoichiometric ratios. Derivatives of Amino-thiazoles have widely
areas of using such as, medicine, materials science, as well as veterinary and
etch. [1]. As well as a derivatives of 2-aminothiazoles, include 2-amino-5-
methythio1,3,4-thiadiazole contain two heterocyclic donor N atoms available for
metal complexation and have been studied potential activities as corrosion
inhibitors [2], for potential antiviral activity [3] and as inhibitors of carbonic
anhydrase [4]. On the base of this, were conducted many syntheses work, for
getting new metal complexes with different derivatives of Amino-thiazoles. In
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this work shown complex on the base of 2-amino-5-methythio1,3,4-thiadiazole
with Zn(II) and acetate (Complex I).
Fig.1.
Molecular structure of Complex I.
Central atom: Zn(II) (represented as a large violet sphere). Coordination
number: 6 — the Zn atom is coordinated to six donor atoms (four nitrogen and
two oxygen atoms), forming an octahedral coordination geometry.
Ligands: The complex contains two molecules of 2-amino-5-methylthio-
1,3,4-thiadiazole, which are coordinated to the Zn(II) atom via a nitrogen atom
from the heterocyclic ring.
The –NH₂ group of each ligand does not participate in coordination, i.e., it is
not bonded to the metal center.
Additionally, carboxylate groups (COO⁻) are present in the complex and are
coordinated to the Zn atom through one or two oxygen atoms, either in a
monodentate or bidentate fashion.
The resulting compound was characterized by elemental analysis, Fourier-
transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Vis)
spectroscopy, proton nuclear magnetic resonance (¹H NMR) (for diamagnetic
Zn), and single-crystal X-ray diffraction (XRD).
X-ray structural data revealed that the Zn(II) ion is six-coordinated, forming
a slightly distorted octahedral geometry. The coordination sphere includes: two
nitrogen atoms from two AMTT ligands (via the endocyclic N atom of the
thiadiazole ring), and four oxygen atoms from two bidentate acetate anions.
Importantly, the –NH₂ group of the AMTT ligand remains non-coordinated and
participates in hydrogen bonding, contributing to crystal packing. The S atom of
the ligand does not participate directly in coordination.
FT-IR spectra show significant shifts in the C=N stretching frequencies
(from 1628 cm⁻¹ to ~1608 cm⁻¹), confirming Zn–N coordination. UV-Vis
analysis exhibits ligand-centered transitions around 280–330 nm, with no d–d
transitions due to the d¹⁰ configuration of Zn(II). The ¹H NMR spectra of the
complex exhibit chemical shift changes compared to the free ligand, especially
for the ring and methyl protons.
The mixed-ligand approach improves the solubility and stability of the
complex. Thermogravimetric analysis (TGA) indicates the compound is
thermally stable up to ~230 °C. SEM-EDX analysis confirms homogeneous
surface morphology and the expected elemental composition.
The successful synthesis of a mixed-ligand Zn(II) complex incorporating 2-
amino-5-methylthio-1,3,4-thiadiazole and acetate demonstrates the ligand’s
THEORETICAL ASPECTS IN THE FORMATION OF
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potential for forming stable coordination compounds. The study offers valuable
insight into ligand-metal interactions, coordination geometry, and the
physicochemical properties of thiadiazole-based systems. Such complexes could
serve as promising candidates in the fields of biological chemistry, catalysis, or
materials science.
Reference
1.Lynch, D. E., Nicholls, L. J., Smith, G., Byriel, K. A. & Kennard, C. H. L. (1999).
Acta Cryst. B55, 758±766
2.Downie, T. C., Harrison, W., Raper, E. S. & Hepworth, M. A. (1972). Acta Cryst.
B28, 1584±1590.
3.Saramet, I. (1975). Farmacia, 23, 35±42.
4.Pedregosa, J. C., Alzuet, G., Borras, J., Fustero, S., Garcia-Granda, S. & Diaz, M. R.
(1993). Acta Cryst. C49, 630±633
