View of Formation, Characterization of Some New Coii, Cuii, Ni II, Au Iiipotassium (2-Carboxyphenyl) (2,3-Dimethylphenyl) Carbamodithioate complexes and Study Their Biological Activity

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Received 20 January 2021; Accepted 08 February 2021.

Formation, Characterization of Some New Coii, Cuii, Ni II, Au Iiipotassium (2- Carboxyphenyl)(2,3-Dimethylphenyl) Carbamodithioate complexes and Study

Their Biological Activity

Ghufran Sh. Al-Obaidy

Corresponding author: [email protected]

Abstract. A new ligand (potassium (2-carboxyphenyl)(2,3-dimethylphenyl)carbamodithioate) is being synthesized and characterized. which has two sulfur donor atoms in it.The ligand was made by reacting one equivalent of carbon disulfide and 2-((2,3-dimethylphenyl)amino)benzoic acid for4 hours in ethanol (as a solvent) in the presence of an alkali base (KOH). The FT-IR , 1HNMR, 13C- NMR , (C.H.N.S), UV-visible, and ESI-mass range, as well as the melting point, were used to describe the dithiocarbamate ligand.Four metal complexes are prepared by refluxing.The complexes were made by reacting two equivalents of potassium dithiocarbamate ligand with one equivalent metal salt for four hours in refluxing ethanol.For certain complexes, FT-IR, UV-Visible, molar conductivity, magnetic susceptibility, solubility of flammable atomic absorption spectroscopy, melting point, element microanalysis, and mass spectroscopy were used to characterize them.The biological effectiveness of the preparedithiocarbamate ligand and the complexes was investigated using the inhibition method in four different bacteria: two Gram positive and two Gram negative bacteria, as well as one pathogenic fungus.

Keywords:Dicarbodithioate,Mefenamic acid, Synthesis.


DTCs (dithiocarbamates) are a class of small organic molecules that have a good ability to chelate metal ions. [1]. There have been several studies and reviews on transition and non-transition metals, suggesting a broad variety of anion compounds. [2]. Organosulfur compounds with dithiocarbamate ligands are more complex. This may be due to the CSS group's low bite angle, which allows it to interact with most metals in the periodic table and has sulfur atoms with the ability to add a single pair of electrons to central metal atom to form complexes [3].DTCs can be stabilized in a variety of metal oxidation states, coordination geometries, and compounds with a wide range of structural variations, from monomeric to polymeric molecular assemblies.The physical and chemical properties of the resulting metal complexes will be determined by the binding properties of dithiocarbamates;

monodentate, bidentate chelating, and bidentate bridging varieties[4].Dithiocarbamate and dithiophosphinate complexes have significant applications..[5] Dithiocarbamates are essential materials that have been studied extensively in coordination chemistry, ((medicine and radiopharmaceutical chemistry)) ,materials science, sensing engineering, and industry. DTCs have shown a wide range of biological effectiveness, inclusive, antibacterial activity [6].


Commercially available laboratory chemicals and reagents may be used without further purification.


Received 20 January 2021; Accepted 08 February 2021.


For ligands and their metal complexes, an element analyzer (C. H. N. S.) was used (Euro EA 3000).

Infrared spectra of potassium bromide disks were taken on a Biotic 600 FT-IR spectrophotometer in the range 4000-400 cm-1, and potassium iodide disks in the range 4000-200 cm-1 on a Shimadzu 8400s FT-IR.Electronic spectra were obtained at room temperature using a Shimadzu 1800 (UV-Vis) spectrophotometer from 200 to 1000 for 10-3 M solutions in dimethyl sulfoxide using quartz cells that were 1.0 cm long. Mass spectra for ligand were obtained using the Shimadzu GC-Mass QPA spectrometer, and mass spectra for complexes were obtained using the Shimadzu LC-MSQP50A Shimadzu (E170Ev) spectrophotometer.Glucosamine Brucker, 400 MHz Ultra Shield model, Germany root, was used to use nuclear magnetic resonance spectra in Deuterated chloroform. The metal signification of complexes is determined using the atomic absorption (A.A) technique and a Shimadzu (A.A 680 GBC 933 plus) spectrophotometer.Glucosamine Brucker, 400 MHz Ultra Shield model, Germany root, was used to use nuclear magnetic resonance spectra in Deuterated chloroform.

The metal signification of complexes is determined using the atomic absorption (A.A) technique and a Shimadzu (A.A 680 GBC 933 plus) spectrophotometer.

Synthesis the ligand

Ligands are made according to a published method [7] with a few tweaks, as discussed below:

Synthesis of potassium (2-carboxyphenyl)(2,3-dimethylphenyl)carbamodithioate

2-((2,3-dimethylphenyl)amino)benzoic acid (0.482g, 0.002 mol) was dissolved in (12 ml) ethanol.

potassium hydroxides (0.112 g, 0.002mol) dissolved in double distilled water (1ml) with 30 minutes of stirring at room temperature, solution cool in the Snow bath. Pure CS2 (0.152g, (0.002mol) be added to thecommixture drop-wise with regular stirring kept at temperature (0-4 ° C) for 4 hours.The brown solution was allowed at room temperature and then evaporated before completing solid brown precipitation. The brown solid was collected by filtration and then recrystallized from methanol, washed with diethylether (10ml) twice and then dried at temperature (35 °C)for 7 hours.

Synthesis of potassium (2-carboxyphenyl)(2,3-dimethylphenyl)carbamodithioatecomplexes A general method for achieving dithiocarbamate complexes was used and as follows: Complexes were synthesisby the reaction of ( 2 potassiumdithiocarbamate salt) equivalent (DTC) as ligand in ethanol with 1 metal salt equivalent as central ion (2:1).Metal chloride solution in 10ml absolute ethanol has been added to a round bottom container, volume (100) ml containing a dithiocarbamate ligand salt solution Meltedat (10) ml ethanol. The commixture of the reaction was shaky and warmed for 4 h under reflux. Filtration was used to bank up the complex, which was then cleaned. with excess methanol and diethyl ether, dried for 48 h [8,9].


The dithiocarbamate ligand was identified in this study. The prepare of this ligand was based on the reaction obtained between NH group with CS2. (KL) was synthesized by combining2-((2,3- dimethylphenyl)amino)benzoic acid with carbon disulfide and KOH as a base with the mole ratio of (1:1) ethanol is used as a solventscheme (1) shows that.The complexes were prepared from reaction (ligand KL with metal chloride salts) in (2:1) mole ratio heated under reflux in ethanol to produce


Received 20 January 2021; Accepted 08 February 2021.

pure complexes, where isolated in moderate yield, as shown in scheme (2).

Scheme (1): Syntheticof ligand KL

Scheme(2):Synthetic of [M(L)2 (H2O)2]H2Oand[Au(L)2 (H2O)(Cl)]complexes


Received 20 January 2021; Accepted 08 February 2021.

Table (1) describes ligand and complexes physical properties.

Table(1)Elemental analysis andPhysical characteristics for the ligand DTC The




Yiel d (%)

M. P (ºC)

Colou r

Found /calcd.




355.51 81 130- 132*

Brown 53.80 (54.0 6)

3.53 (3.9 7)

4.13 (3.9 4)

17.49 (18.0

4) [Co


745.80 74 200* Blue 51.15 (51.54


4.07 (4.60


3.87 (3.76


16.98 (17.1

7.47 (7.90)

O 9)

[Cu (L)2(H2O)2]H2

750.42 79 215* Gray 51.04 (51.22


4.49 (4.57


3.82 (3.73


16.51 (17.0

7.87 (8.47)

O 9)

[Ni (L)2(H2O)2]H2O

745.56 64.


270* Light green

51.13 (51.55


4.04 (4.60


3.89 (3.76


16.97 (17.2


7.43 (7.87)

[Au(L)2(H2O) Cl]

883.26 77.


293* brown 43.24 (43.52


3.28 (3.42


3.48 (3.17


14.23 (14.5

21.74 (22.3

2) 0)

*= decomposed; m.p= melting point; Calc.= Calculated

The 1HNMR,13CNMR and Mass spectraof ligand KL

1H_NMR spectra of ligand KL(Fig.1(showedthe characteristicchemical shift of the solventCDCl3)at δ=7.23. The spectrumpresented singlet chemical shifts at δ =13.17 ppm attributed to the one proton for carboxylicacid[10].The spectrum of two singlet signalwas displayed at δ =2.13, 2.26 ppm attributed to the one proton for CH3[11]. The signal at =8.07 , 7.57, 7.41, 7.30, 7.15, 7.04 ppm wereassignedfor protons of CH (benzene ring)[12,13]. The 13C-NMR spectrum, in CDCl3 solvent wasdisplayedin (Fig.2(. The prepare of ligand has been revealed throughspotting signal in δ =196.69ppm , that can be refer to carbon atom C1 for CS2group [14]. The carbon atoms C2at δ=166.66 ppm, that can be attributed to carboxyl group[10].The carbon atoms( C3-C14 )be received with the chemical shifts at δ= 140.97,138.48, 135.32, 133.15, 130.71, 128.79, 125.64, 124.07, 120.69, 118.43, 115.33, 113.18 ppm, respectively wereassignedfor C (benzene ring) [15]. Finally, the chemical shift at δ=77.45 ppm attributed to CDCl3 solvent.The electrospray (+) mass spectrafor KL is obtainable in(Fig.3).The spectra exhibits fragments belong to ligand composition. Parent ion peak of the ligand is spottedin m/z = 355which corresponds to (M+H)+(%) for C16H14KNO2S2 ; requires = 355.01.


Received 20 January 2021; Accepted 08 February 2021.

Figure (1) 1HNMR spectraforligand KL(CDCl3as solvent).

Figure (2) 13CNMR spectrafor ligand KL(CDCl3 as solvent).


Received 20 January 2021; Accepted 08 February 2021.

Figure (3) mass spectrafor ligand KL

Mass Spectra for the complexes

Mass spectrafor some complexes is presented at (Fig 4-5). Spectra exhibits fragments refer to complexes composition. Parent ion peak are observed at m/z = 745 and 755 which corresponds to (M+H)+ (%) for [Co(L)2 (H2O)2]H2O, [Cu(L)2 (H2O)2]H2O ; requires = 745.06 and749.05respectively.

Figure (4): mass spectraforcomplex [Co(L)2 (H2O)2]H2O


Received 20 January 2021; Accepted 08 February 2021.

Figure (5): mass spectraforcomplex [Cu(L)2 (H2O)2]H2O

The FTIR spectrum for ligand and complexes

The FTIR spectrum of (KL) shows no bands(disappeared) around 3339.5 cm-1which belong to υ(NH) [16]. FTIR spectrum reveals new bands in 1469 cm-1refer to υ(C-N) for (N-CS2) group [17].

Also,two new bands are revealed by the FTIR spectrum at 1001 cm-1 and 885 cm-1 belong to νas (CS2) and νs (CS2),respectively [18].The band in1595cm-1 isrefer to νar (C=C) for aromatic ring[19].In addition, the spectra displayed a bands in 1235 cm-1 and648 cm-1 attributed for the υ (C–N) and υar(C–S) respectively [20]. Bands are outlined in Tables (2).

Table (2)KL ligand's FTIR spectral information and its complexes Compound ν (O-H)

carboxy l

ν (C-H) aromati


ν (C=O ) carboxy


ν (C=C ) aromati


ν(N- CS2)





ν(M -S)

ν(M -O)

(KL) 3077 3070 1658 1595 146


1001 885 - -

[Co (L)2(H2O)2]H2


3082 3080 1660 1573 1489 1015 990 400 598

[Cu (L)2(H2O)2]H2


3079 3054 1660 1565 1455 1034 887 398 587

[Ni (L)2(H2O)2]H2


3086 3023 1660 1589 1479 1147 899 375 583


Received 20 January 2021; Accepted 08 February 2021.

[Au(L)2(H2O) Cl]

3090 3065 1660 1584 1500 1109 993 315 580

UV-Vis spectral data for DTC (KL) and the complexes

In dimethyl sulfoxide solution, the UV-Vis spectrum of KL shows peaks at (273nm = 36630 cm-1 ; εmax = 1310 molar-1 cm-1)and (360 nm = 28571 cm-1; εmax = 1000 molar-1 cm-1) refer to“π → π*”,“n → π*”transitions, respectively [22],show in Table (3). Most complexes are colored. Such colors vary from ligands and transition metal salts, so these colors are considered essential indicators of coordination, so the colored complexes show different bands of absorption in location and intensity[23]

Table 3. UV,Vis spectrumfor ligand and complexes( in 10−3 M DMSO)

Compound λ ύ εmax. Assignment Suggested


(KL) 273 36630 1310 π→π *

360 27777 1000 n→π *

[Co(L)2(H2O)2]H2O 310 370

32258 27027

1580 700

L. F L. F C. T overlap


4T1g(F) → 4A2g(F)


460 21739 733

650 15384 300

[Ni(L)2 (H2O)2]H2O 272 390

36764 25641

480 400

L. F L. F C. T overlap

3A2g(F) → 3T1g(F)


450 22222 300

700 14285 200

[Cu(L)2(H2O)2]H2O 276 370

36231 27027

580 330


Distorted Octahedral

430 23255 250 C.T

724 13812 115 2Eg →2T2g


Received 20 January 2021; Accepted 08 February 2021.

[Au(L)2(H2O) Cl] 300 346 456


33333 28901 21929


2252 1360 1210


L.F L.F C.T overlap

3A2g (F)


3A2g (F)



Molar conductivities and magnetic susceptibility

The low molar conductivities of CoII, NiII,CuII,and Au III complexes at DMSO (17.4, 18.3, 19.2, and 16.4 ohm-1.cm2.mol–1), respectively, mean the complexes are non - electrolytes [24]. Measuring the Co complex magnetic moment yields a meff value at 4.27 B.M. CoII complex to octahedral geometries is given this value. 3.01 B.M. values were obtained from the Ni-complex.The meff value for this complex is included in the octahedral array, indicating a high geometry spin around NiII ion.

Cu-complex meff value is 1.98 B.M, refer to the octahedral formulato the Cu II ion. The complex AuIII is diamagnetic. Two unpaired electrons should be paramagnetic if the complex is in complete octahedral configuration. Despite this, the AuIII ion inspireextreme ligand field splitting due to its high oxidation state and heavy metal character, and the ideal octahedral configuration must be unstable since two electrons can occupy e.g. high-energy orbitals. As a result of the tetragonal distortion, the eg orbitals will be divided, making the AuIII complex diamagnetic. [25].

Biological effect

Biological effectforsynthesiseddithiocarbamate ligandand its complexes were calculatedthrough using inhibition wayfor four types of bacteria and one kind of pathogenicfungus [26]. twokind of bacteria was gram positive which is( Staphylococcus aureus,Bacillus subtilis) the second two was gram negative which is(Escherichia coli, Pseudomonas aeruginosa) and thepathogenic fungus was Candida. This is toestimate their potential antimicrobial activity. the biological activity of DMSO showed no activity against (the bacterial strains) [27]. Inhibition circle diameters in millimetre unit are listed in Tables (4). Figures (5) screen the effect of the synthesized dithiocarbamate compounds on bacterial strains andpathogenic fungus.

Table (3): biological effect for KLligand and the complexes (M(L)2) No Compounds Bacillus


Staphylococ cus aureus(G+)

Pseudomonas aeruginosa(G−)

Escherichia coli(G−)


1 Control (DMSO)

0 0 0 0 0

2 KL

22 23 30 18 24

3 [Co (L)2 (H2O)2]H

2O 20 21 34 22 19


Received 20 January 2021; Accepted 08 February 2021.

4 [Cu (L)2 (H2O)2]H

2O 24 22 29 30 22

5 [Ni (L)2 (H2O)2]H2

O 19 20 25 24 21

6 [Au (L)2 (H2O)Cl]

25 23 27 27 25

Figure (5): Evolution of diameter zone (mm) for inhibition ofKL ligand and the complexes (M(L)2) with the growth of various bacterial strains and pathogenic fungus.


The study of ligands and their complexes, as well as their preparation. The ligand complexes are made by reacting 2 potassium dithiocarbamate salt equivalent (DTC) with 1 metal salt equivalent as the central ion in ethanol. To check bonding mode and over all complex structure, physicochemical and spectroscopic methods have been implemented.These findings led to the development of four coordinate complexes, with the octahedral structure for complexes being proposed on fundamentthe previous dispute. Biological effect of the prepereddithiocarbamate ligand and the complexes was investigated using inhibition method in four types of bacteria: (two gram positive and two gram negative bacteria), Add toone pathogenic fungus.It will be determined if they have antimicrobial activity. In general, the tests show that the ligands and their complexes have strong antibacterial and antifungal activity against various bacteria and pathogenic fungi.


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