INTRODUCTION:

Schiff bases and their corresponding metal complexes have attracted a good deal of interest in coordination chemistry because of their diverse structural characteristics and wide applicability in several biological, industrial, and catalytic processes. A Schiff base is usually formed by a condensation reaction between a primary amine and a carbonyl group with the concomitant formation of an azomethine (-C=N-) group that is a good site for metal attachment.

These ligands can support the incorporation of numerous metal ions, paving the way for the development of metal complexes with different biological and chemical activities^1-5.

In particular, thiazole-derived Schiff bases have received attention due to the thiazole ring present in the ligand, which increases their biological activity. Thiazole derivatives are widely reported to show a wide range of biological activity, such as antimicrobial, anticancer, anti-inflammatory, and antioxidant. In the case of these ligands also, biological activity increases quite often by introducing metal ions into the ligand since they tend to change the structural conformation of the ligand and alter its reactivity, which enhances its bioavailability and activity as well^6-11.

The present study intends to prepare a new thiazole-based Schiff base ligand along with its metal complexes with Co, Ni, Cu, and Zn ions. The characterized compounds will be analyzed using FTIR, UV-Vis, NMR, elemental, and X-ray diffraction (XRD) techniques to establish the structures and coordination patterns of the synthesized compounds.

EXPERIMENTAL:

Materials and Methods:

All chemicals used were of analytical reagent (AR) grade and were employed without further purification. Terephthaldehyde, CoCl₂·6H₂O, NiCl₂·6H₂O, CuCl₂·2H₂O, and ZnCl₂·2H₂O were purchased from Sigma-Aldrich, while 5-methylthiazole-2-amine was obtained from Metropolitan Exim-Chem Ltd., India. Commercial organic solvents were used for synthesis. Elemental analysis (C, H, and N) was carried out using a Thermo Scientific FLASH 2000 analyzer. Molar conductance measurements were performed in DMSO (1 × 10⁻⁴ M) at room temperature using an EI Delux digital conductivity meter. FT-IR spectra were recorded on a Bruker Alpha-II spectrometer in the range 4000–400 cm⁻¹. UV–Vis spectra were obtained in DMSO (5 × 10⁻⁴ M) using a LABINDIA UV-3092 spectrophotometer in the range 200–600 nm. ¹H NMR spectra were recorded in DMSO-d₆ on a JEOL Delta-550 spectrometer operating at 400 MHz using tetramethylsilane (TMS) as an internal reference. Thermal analysis (TG/DTA) was carried out on an EXSTAR TG/DTA-6300 instrument under a nitrogen atmosphere at a heating rate of 10 °C min⁻¹ up to 1000 °C. Powder X-ray diffraction patterns were recorded using a Bruker D-8 Advance diffractometer. Cyclic voltammetry measurements were performed using a Metrohm Autolab PGSTAT128N at room temperature.

Synthesis of Schiff Base Ligand (LA):

The Schiff base ligand (LA) was synthesized by reacting terephthaldehyde with 5-methylthiazole-2-amine under mild reflux conditions. A methanolic solution of terephthaldehyde (1.34 g, 10 mmol in 20 mL MeOH) was stirred and treated dropwise with a methanolic solution of 5-methylthiazole-2-amine (3.78 g, 20 mmol). A few drops of glacial acetic acid were added to promote the condensation reaction. The reaction mixture was maintained at 50–60 °C for 40 min, during which a yellow precipitate formed. The progress of the reaction was monitored by thin-layer chromatography (TLC).

The resulting solid was filtered, washed thoroughly with small portions of methanol and diethyl ether, and recrystallized from methanol to obtain a pure yellow crystalline product. The compound was dried under vacuum and stored over fused CaCl₂.

Molecular formula: C₁₆H₁₄N₄S₂; Molecular weight: 326.44 g mol⁻¹; Yield: 80%; Color: Yellow; Melting point: 188 °C; Solubility: Readily soluble in DMF and DMSO; partially soluble in EtOH, MeOH, and CHCl₃; insoluble in non-polar solvents; Anal. Calcd. (%): C 58.87, H 4.32, N 17.16, S 19.64; Found (%): C 58.86, H 4.31, N 17.14, S 19.62; FT-IR (cm⁻¹): 1607 [ν(C=N) azomethine], 737 [ν(C–S–C)]; UV–Vis (DMSO, λmax nm): 278, 355; ¹H NMR (400 MHz, DMSO-d₆, δ ppm): 8.67 (s, CH=N), 6.78–8.19 (m, aromatic protons), 2.45–2.55 (s, CH₃); Molar conductance (DMSO): λₘ = 22.1 Ω⁻¹ cm² mol⁻¹

Synthesis of the Metal Complexes [M₂(HL)(H₂O) ₄(Cl)₄]:

(M = Co (II), Ni (II), Cu (II), and Zn (II))

The metal (II) complexes were synthesized by reacting a methanolic solution of the metal salts (2 mmol) with a methanolic solution of the Schiff base ligand LA (HL) (1 mmol) in a slightly alkaline medium. The reaction mixtures were continuously stirred and heated on a magnetic hot-plate stirrer at 50–60 °C for 4–5 h. The progress of the reaction was monitored by TLC.

The colored precipitates obtained were filtered, washed several times with small quantities of methanol and diethyl ether, and recrystallized from methanol. The purified complexes were dried and preserved in a desiccator over fused CaCl₂ under vacuum.

Metal Complex (LA-A):

Complex with molecular formula [C₁₆H₂₂Cl₄Co₂N₄O₄S₂]·2H₂O; Molecular weight: 694.16 g mol⁻¹; Yield: 74%; Color: Brown; Decomposition temperature: > 358 °C; Stability: Stable; Solubility: Partially soluble in EtOH, MeOH, and CHCl₃; soluble in DMSO and DMF; insoluble in non-polar solvents. Anal. Calcd. (%): C 29.20, H 3.37, Cl 21.54, N 8.51, O 9.72, Co 17.91; Found (%): C 29.18, H 3.35, Cl 21.50, N 8.48, O 9.70, Co 17.88; FT-IR (selected bands, cm⁻¹): 1596 [ν(C=N) azomethine], 3407 [ν(H₂O) coordinated], 738 [ν(C–S–C)], 536 [ν(M–N)]; UV–Vis (λmax nm): 303, 373; Molar conductance (DMSO): λₘ = 24.30 Ω⁻¹ cm² mol⁻¹.

Metal Complex (LA-B):

Complex with molecular formula [C₁₆H₂₂Cl₄Ni₂N₄O₄S₂]·2H₂O; Molecular weight: 693.68 g mol⁻¹; Yield: 73.5%; Color: Reddish brown; Decomposition temperature: > 358 °C; Stability: Stable; Solubility: Partially soluble in EtOH, MeOH, and CHCl₃; soluble in DMSO and DMF; insoluble in non-polar solvents.

Anal. Calcd. (%): C 29.22, H 3.37, Cl 21.56, N 8.52, S 9.75, O 9.73, Ni 17.85; Found (%): C 29.20, H 3.35, Cl 21.52, N 8.50, S 9.72, O 9.71, Ni 17.82. FT-IR (selected bands, cm⁻¹): 1590 [ν(C=N) azomethine], 3368 [ν(H₂O) coordinated], 734 [ν(C–S–C)], 520 [ν(M–N)].UV–Vis (λmax nm): 304, 385. Molar conductance (DMSO): λₘ = 28.7 Ω⁻¹ cm² mol⁻¹.

Metal Complex (LA-C):

Complex with molecular formula [C₁₆H₂₂Cl₄Cu₂N₄O₄S₂]·2H₂O; Molecular weight: 703.39 g mol⁻¹; Yield: 70.91%; Color: Orange; Decomposition temperature: > 358 °C; Stability: Stable; Solubility: Partially soluble in EtOH, MeOH, and CHCl₃; soluble in DMSO and DMF; insoluble in non-polar solvents.

Anal. Calcd. (%): C 28.80, H 3.32, Cl 21.25, N 8.40, S 9.61, O 9.59, Cu 19.04; Found (%): C 28.79, H 3.30, Cl 21.23, N 8.38, S 9.58, O 9.57, Cu 19.01. FT-IR (selected bands, cm⁻¹): 1594 [ν(C=N) azomethine], 3385 [ν(H₂O)], 736 [ν(C–S–C)], 524 [ν(M–N)]; UV–Vis (λmax nm): 306, 381; Molar conductance (DMSO): λₘ = 29.20 Ω⁻¹ cm² mol⁻¹.

Metal Complex (LA-D):

Complex with molecular formula [C₁₆H₂₂Cl₄Zn₂N₄O₄S₂]·H₂O; Molecular weight: 689.06 g mol⁻¹; Yield: 73.12%; Color: Reddish brown; Decomposition temperature: > 358 °C; Stability: Stable; Solubility: Partially soluble in EtOH, MeOH, and CHCl₃; soluble in DMSO and DMF; insoluble in non-polar solvents.

Anal. Calcd. (%): C 28.64, H 3.30, Cl 21.13, N 8.35, S 9.54, O 9.56, Zn 19.49; Found (%): C 28.62, H 3.27, Cl 21.11, N 8.33, S 9.53, O 9.54, Zn 19.46. FT-IR (selected bands, cm⁻¹): 1578 [ν(C=N) azomethine], 3364 [ν(H₂O)], 733 [ν(C–S–C)], 538 [ν(M–N)]. UV–Vis (λmax nm): 305, 379. Molar conductance (DMSO): λₘ = 26.4 Ω⁻¹ cm² mol⁻¹.

(LA)

RESULT AND DISCUSSION:

Molar conductivity:

The molar conductance of the synthesized Schiff base ligand LA and its metal complexes was measured in DMSO at room temperature using a concentration of 5 × 10⁻⁴ M. The observed molar conductance (λm) values fall within the range of 22.1–29.4 Ω⁻¹ cm² mol⁻¹, indicating the non-electrolytic nature of the metal complexes (Table 3)^12-14.

IR studies:

The FT-IR spectra of the Schiff base ligand (LA) and its metal complexes LA-A(Co), LA-B(Ni), LA-C(Cu), and LA-D(Zn) were recorded to elucidate the coordination behavior of the ligand and to confirm complex formation. The significant absorption bands and their assignments are summarized in Table 2.

The FT-IR spectrum of the free ligand LA exhibits a strong absorption band at 1607 cm⁻¹, attributed to the azomethine (C=N) stretching vibration, confirming Schiff base formation. Upon coordination with metal ions, this band shifts to lower wavenumbers in the range 1596–1578 cm⁻¹ in all complexes, indicating the involvement of the azomethine nitrogen atom in coordination. Minor changes in the thiazole ring vibrations, together with the absence of any significant shift associated with C–S–C stretching, support coordination through the thiazole ring nitrogen atom rather than sulfur. Broad absorption bands observed in the region 3364–3407 cm⁻¹ in the spectra of all metal complexes are assigned to O–H stretching vibrations of coordinated water molecules. The formation of the metal complexes is further confirmed by the appearance of new bands in the low-frequency region. Bands observed at 520–538 cm⁻¹ are attributed to metal–nitrogen (M–N) stretching vibrations arising from coordination through azomethine and thiazole nitrogen atoms, while weak bands in the region 401–408 cm⁻¹ are assigned to metal–chloride (M–Cl) stretching vibrations, confirming the coordination of chloride ions.

Overall, the FT-IR spectral data clearly demonstrate that the Schiff base ligand coordinates to the metal ions in a bidentate manner through the azomethine nitrogen and thiazole nitrogen atoms, with chloride ions and coordinated water molecules completing the coordination environment in all synthesized complexes^15-18.

Table 2: IR data of the synthesized LA Schiff base ligand and its metal complexes

Samples	C=N (azomethine)	Coordinated (H₂O)	C-S-C	M-N (Thiazole Ring)	M-Cl
LA	1607	-	737	-
LA-A(Co)	1596	3407	738	536	406
LA-B(Ni)	1590	3368	734	520	401
LA-C(Cu)	1594	3385	736	524	408
LA-D(Zn)	1578	3364	733	538	402

Figure 1: shows the transmittance graph of LA ligand and its metal complexes

Electronic spectra studies:

The electronic absorption spectra of the Schiff base ligand LA and its metal complexes LA-A(Co), LA-B(Ni), LA-C(Cu), and LA-D(Zn) were recorded to explore the character of the electronic transitions. The data on the absorption bands are presented in Table 3. The UV-Visible spectrum of the free ligand LA displayed two sharp absorption bands at 278 nm and 355 nm. The bands in the lower wavelength region are due to the π→π* transitions in the aromatic rings, while those in the higher wavelength region are due to n→π* transitions in the C=N chromophore. The two sharp absorption bands in the free ligand LA were found to undergo prominent bathochromic shifts upon interaction with the metal ions. The positions of the π→π* transitions in the complexes were found in the regions 303-306 nm, while the n→π* transitions were found in the regions 373-385 nm. Among these, the highest wavelength corresponding to the n→π* transition was shown by LA–B(Ni) at 385 nm, indicating thereby a strong metal–ligand interaction. The other Co(II), Cu(II) and Zn(II) complexes exhibited similar shifts in the lower energy region and were thus confirmed by the coordination of azomethine nitrogen. The red shifts in the absorption bands also support the coordination of metal ions and, therefore, the stabilisation of excited states upon coordination. Overall, the UV-visible spectral data strongly support the involvement of an azomethine group for coordination and are in tune with the proposed structures of synthesized Schiff base metal complexes^19-22.

Table 3: Shows the electronic absorption data of the LA ligand and its metal complexes

Samples	π→π*	n→π*	Molar conductance (*Ω⁻¹ cm² mol⁻¹)*
LA	278 nm; 35,971 cm⁻¹	355 nm; 28,169 cm⁻¹	22.1
LA-A(Co)	303 nm; 33,003 cm⁻¹	373 nm; 26,809 cm⁻¹	24.3
LA-B(Ni)	304 nm; 32,895 cm⁻¹	385 nm; 25,974 cm⁻¹	28.7
LA-C(Cu)	306 nm; 32,680 cm⁻¹	381 nm; 26,247 cm⁻¹	29.2
LA-D(Zn)	305 nm; 32,787 cm⁻¹	379 nm; 26,386 cm⁻¹	26.4

Figure 2: Shows the electronic absorbance spectra of LA ligand and its metal complexes.

¹H and ¹³C NMR Spectral Analysis:

The ¹H NMR spectrum of the ligand LA was recorded in DMSO-d₆. A sharp singlet observed at δ 8.67 ppm is characteristic of the azomethine proton (-CH=N), confirming the formation of the imine group. Multiplet signals distributed over the range δ 6.78-8.19 ppm are assigned to the aromatic protons of the benzene and heteroaromatic rings. Additionally, a singlet in the upfield region at δ 2.45-2.55 ppm corresponds to the methyl group attached to the heterocyclic moiety.

The ¹³C NMR spectrum in DMSO-d₆ further supported the proposed structure. A downfield signal appearing at δ 162 ppm was attributed to the C=N carbon of the imine group. Aromatic carbons resonated within δ 130-139 ppm. A methyl carbon signal was observed around δ 39.9-40 ppm, consistent with substitution at the heterocyclic unit.

These NMR features collectively confirm the successful formation of the Schiff base ligand and support its proposed structure^23,24.

Table 4 shows the steps of thermal degradation of ligand LA and its metal complexes

Samples

Degradation

Step

Temp. range (°C)

Wt. loss (%)

Total weight lose Obs.

(Cal.%)

Assignments

Residue Obs.%(Cal.%)

Obs.

Cal.

LA-A(Co)

1^st

2^nd

3^rd

4^th

35-99.5

99.5-215.4

215.4-570

570-990

5.18

10.44

18.65

34.71

5.2

11.4

19.08

36.98

68.98

(72.66)

two H₂O lattice

4 Coordinated H₂O

C₆H₇N+HCl

C₃N₂+C₆H₆+2Cl+NH₃+CS

2CoO(21.58) + residue OTHER IMPURITIES carbide and sulphides 9.49

(5.76)

LA-B(Ni)

1^st

2^nd

3^rd

4^th

30-120

120-230

230-470

470-990

5.18%

15.42

16.43

41.37

5.4%

14.6

16.6

38.39

78.4

(74.99)

2 H₂O lattice

4H₂O coordinated

+Cl

2Cl+CH₄+HCN

C₃N₂+NH₃+C₁₁H₁₀S₂

2NiO (21.5) +

Carbide and other impurities (3.51)

LA-C(Cu)

1^st

2^nd

3^rd

4th

38.8-98.5

98.5-380

380-750

750-990

5.11

20.33

20.04

30.2

5.2

20.4

19.8

29.8

75.38

(75.2)

2 lattice H₂O

4 coordinated H₂O+Cl+HCl

C₅H₄N+HCN+HCl

C₃N₂+C₆H₆+C₂H₆+2S

2CuO (19.81) +

4.51% Carbide impurities

24.31 (25.12)

LA-D(Zn)

1^st

2^nd

3^rd

42-220

220-660

660-990

21.47

29.60

20.3

30.7

71.07

(72)

One lattice H₂O + 4H₂O coordinated +HCl + N

2HCl+ C₅H₄N

C₆H₆+C₃N₂+C₂H₂+HCl

2ZnO (23.62%) + Carbide impurities + by- product 4.6 (4.38)

Powder X-ray Diffraction (XRD) Analysis:

The powder X-ray diffraction patterns of the Schiff base ligand LA and its metal complexes were recorded to examine their crystalline nature and the effect of metal coordination on structural organization. The PXRD pattern of the free ligand LA shows a prominent diffraction peak at 2θ = 19.6°, corresponding to an interplanar spacing (d) of 4.53 Å, indicating its semi-crystalline nature.

Upon coordination with transition metal ions, noticeable changes in the diffraction patterns are observed, including shifts in peak positions and variations in intensity, confirming the formation of new metal–ligand assemblies. The metal complexes exhibit their major diffraction peaks in the region 2θ = 22.17°–22.27°, with corresponding d-spacing values of approximately 4.00 Å, suggesting changes in lattice arrangement following coordination.

The average crystal

lite sizes were estimated using the Debye–Scherrer equation. The ligand exhibits a small crystallite size (2.59 nm), while the metal complexes show moderately larger crystallite sizes in the range of 3.29–6.19 nm, indicating improved crystallinity upon metal coordination.

Overall, the PXRD results suggest that coordination with metal ions leads to enhanced structural ordering and slightly increased crystallinity of the synthesized complexes. The observed changes in crystallite size and d-spacing values support the formation of new coordination compounds^29-32.

Figure 5: Powder XRD graph of synthesized Schiff base ligand LA and its metal complexes

Electrochemical Studies:

Cyclic voltammetry was employed to investigate the electrochemical characteristics of the newly synthesized Schiff base ligand LA and its metal complexes LA-A (Co), LA-B (Ni), LA-C (Cu), and LA-D (Zn). Individual solutions of the ligand and complexes were prepared in DMSO containing 0.1 M tetrabutylammonium perchlorate (TBAP) as the supporting electrolyte. The electrochemical responses were recorded at a scan rate of 100 mV s⁻¹ within the potential window of −1.5 to +1.5 V.

The cyclic voltammogram of the free ligand LA exhibits a well-defined redox couple with anodic and cathodic peak potentials at 0.551 V and −1.01 V, respectively, resulting in a peak potential separation (ΔE) of −0.460 V. This redox behavior is attributed to the electroactivity of the azomethine (-CH=N-) group and the conjugated system present in the ligand framework. The low current ratio (Ia/Ic = 0.203) indicates a quasi-reversible electron transfer process.

Upon coordination with metal ions, significant changes in the redox parameters are observed, confirming successful complex formation. The Co(II) complex LA-A displays anodic and cathodic peaks at 0.702 V and -1.071 V, respectively, with a reduced ΔE value (-0.371 V) and an increased current ratio (0.342), suggesting enhanced electron transfer due to metal-ligand interaction. The Ni(II) complex LA-B shows a comparatively larger peak separation (ΔE = -0.559 V), indicative of a more irreversible redox process, which may be attributed to stronger metal–ligand bonding and slower charge transfer kinetics. The Cu(II) complex LA-C exhibits a quasi-reversible redox couple with anodic and cathodic peak potentials at 0.746 V and -1.005 V, respectively. The smaller peak separation (ΔE = -0.259 V) along with the highest current ratio (Ia/Ic = 0.402) among the complexes reflects improved electrochemical activity, consistent with the redox-active Cu(II)/Cu(I) system. In contrast, the Zn(II) complex LA-D shows relatively weaker electrochemical response with lower anodic potential and current ratio, which is expected due to the redox-inactive nature of Zn(II).

The half-wave potentials (E₁/₂) of the metal complexes are shifted compared to the free ligand, further supporting coordination-induced electronic redistribution. The peak potential separations exceeding 59 mV and Ia/Ic values less than or close to unity suggest that all metal complexes undergo quasi-reversible, one-electron redox processes, which can be ascribed to the M(II)/M(I) redox couple. Overall, the cyclic voltammetric results demonstrate that metal coordination significantly influences the redox behavior of the Schiff base ligand, and the observed electrochemical features are consistent with the proposed structures of the synthesized complexes^33-36.

Table 5 represented the cyclic voltammogram data of the Schiff base ligand LA and its metal complexes

Samples	Epa (V)	Epc (V)	^a∆E (V)	Ia/Ic	^bE_1/2 (V)
LA	0.551	-1.01	-0.460	0.203	0.791
LA-A (Co)	0.702	-1.071	-0.371	0.342	0.885
LA-B (Ni)	0.641	-1.202	-0.559	0.255	0.920
LA-C (Cu)	0.746	-1.005	-0.259	0.402	0.875
LA-D (Zn)	0.488	-0.88	-0.392	0.205	0.741

^a∆E(V) = Epa-Epc , ^bE_1/2 (V) = 𝑬𝒑𝒂+𝑬𝒑/2

Figure 6: Cyclic voltammogram graph of the synthesised Schiff base ligand LA and its metal complexes

CONCLUSION:

Schiff base ligands containing heterocyclic moieties have attracted considerable attention due to their versatile coordination behavior, structural flexibility, and potential applications in catalysis, bioinorganic chemistry, and materials science.

A novel tetradentate thiazole-based Schiff base ligand was successfully synthesized and subsequently employed for the preparation of its binuclear Co(II), Ni(II), Cu(II), and Zn(II) metal complexes. The formation of the ligand and its corresponding complexes was confirmed through comprehensive analytical and spectroscopic techniques. Elemental analysis and molar conductance measurements validated the proposed stoichiometry and indicated the non-electrolytic nature of all complexes. Spectroscopic investigations, including FT-IR, UV–Visible, and NMR analyses, clearly revealed coordination through the azomethine nitrogen atoms along with the heteroatomic donor sites of the thiazole moiety. All the synthesised metal complexes exhibit a binuclear octahedral arrangement, with the Cu(II) complex showing a distorted octahedral geometry due to the Jahn–Teller effect. Powder X-ray diffraction studies demonstrated the slightly crystalline nature of the ligand and its complexes, with noticeable structural modification upon metal coordination.

ACKNOWLEDGEMENTS:

We thankful to, Department of Chemistry and Department of Botany, Dr. Hari Singh Gour University, Sagar for providing indispensable facilities during research work. I am also thankful to the Department of Chemistry, Gyan Sagar College of Engineering (GSCE), Sagar, Madhya Pradesh, for providing the necessary facilities.

COMPETING INTERESTS:

The authors declare no conflict of interest, financial or otherwise.

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Received on 15.02.2026 Revised on 21.03.2026

Accepted on 20.04.2026 Published on 27.05.2026

Available online from May 30, 2026

Asian J. Research Chem.2026; 19(3):211-220.

DOI: 10.52711/0974-4150.2026.00033

This work is licensed under a Creative Commons Attribution-Non Commercial-Share Alike 4.0 International License. Creative Commons License.

No	Reaction	Complex MF [F. Wt.]	Colour	Yield (%)	MP (°C)	Elemental analysis % calc. (found) C H N S O Cl M
(1)	LA	[C₁₆H₁₄N₄S₂] [326.44]	Yellow	80%	190	58.87 4.32 17.16 19.64 - - - (58.86) (4.30 ) (17.14) (19.62)
(2)	LA-A(Co)	[C₁₆H₂₂Cl₄Co₂N₄O₄S₂] 2H₂O [694.16]	Brown	74%	>300	29.20 3.37 8.51 9.74 9.72 21.54 17.91 (29.18) (3.35) (8.48) (9.72) (9.70) (21.50) (17.88)
(3)	LA-B(Ni)	[C₁₆H₂₂Cl₄Ni₂N₄O₄S₂]. 2H₂O [693.68]	Reddish brown	73.5%	>300	29.22 3.37 8.52 9.75 9.73 21.56 17.85 (29.20) (3.35) (8.50) (9.72) (9.71) (21.52) (17.82)
(4)	LA-C(Cu)	[C₁₆H₂₂Cl₄Cu₂N₄O₄S₂].2H₂O [703.39]	Brown	70.91%	>300	28.80 3.32 8.40 9.61 9.59 21.25 19.04 (28.79) (3.30) (8.38) (9.58) (9.57) (21.23) (19.01)
(5)	LA-D(Zn)	[C₁₆H₂₂Cl₄Zn₂N₄O₄S₂]. H2O [689.06]	Reddish yellow	73.12%	>300	28.64 3.30 8.35 9.56 9.54 21.13 19.49 (28.62) (3.27) (8.33) (9.54) (9.53) (21.11) (19.46)