MIXED LIGAND COORDINATION COMPOUNDS OF PALMITATE, OLEATE WITH CALCIUM ACETAMIDE CARBAMIDE AND THIOCARBAMIDE

ABSTRACT

Based on the data of IR spectroscopy, it was established that the molecules of formamide, acetamide, carbamide and thiocarbamide anions of fatty acids are coordinated through the oxygen atom. The thiocarbamide molecules are coordinated, respectively, through the sulfur atom of the thioamide group and the nitrogen heteroatom of the pyridine ring. Palmitate, oleate, stearate anions, depending on the composition of the geometric configuration of the coordination sites, exhibit mono- and bidentate-cyclic coordination. In the IR absorption spectrum of a free urea molecule, along with other frequencies, two bands are observed, which confirm the presence of a coordination bond between the central ion and oxygen atoms of the urea molecule.

АННОТАЦИЯ

На основании данных ИК-спектроскопии установлено, что молекулы формамида, ацетамида, карбамида и тиокарбамида и анионов жирных кислот координированы через атом кислорода. Молекулы тиокарбамида и никотинамида координированы соответственно через атом серы тиоамидной группы и гетероатом азота пиридинового кольца. Пальмитатные, олеатные, стеаратные анионы в зависимости от состава геометрической конфигурации координационных центров проявляют моно- и бидентатно-циклическую координацию.В ИК-спектре поглощения свободной молекулы мочевины наряду с другими частотами наблюдаются две полосы, подтверждающие наличие координационной связи между центральным ионом и атомами кислорода молекулы мочевины.

Keywords: mixed complex compounds, coordination, central atom, synthesis, methods of coordination, thermal behavior, individuality.

Ключевые слова: смешанные комплексные соединения, координация, центральный атом, синтез, методы координации, термическое поведение, индивидуальность.

Introduction. Actual task of modern chemistry is the search new environmentally clean methods for the synthesis of chemical compounds and based on them materials. One of these methods is mechanochemical. Besides the fact that mechanochemical activation in the absence of solvents is at the synthesis stage, the generated mechanical energy leads to the breaking of bonds and the formation of certain intermediate products, which cannot be formed in the presence of a solution, therefore, often as a result of mechanochemical reactions, new compounds are formed, which cannot be obtained under the conditions of use of solvents [6, p.35].

Substances containing donor atoms, for example, amides of aliphatic, carboxylic, pyridinecarboxylic acids, in particular acetamide and nicotinic acid contribute to the formation of coordination compounds with metal ions. Anions of Organic and Inorganic Acids (acetic, benzoic, stearic, oleic, palmitic, nicotine, nitrogen, etc.) depending on the synthesis conditions, the nature of metals and the composition of complexes exhibit diverse methods of coordination [9, p.142; 11, p. 2963]. Numerous studies on the coordination compounds of p, d, and f metals with acid amides are devoted to complexes with homogeneous ligands [7 p.820; 10 p.535]. There are no data in the literature of monotype ligand coordination compounds of zinc nitrate with acetamide and nicotinic acid [8, p.181].The reasons for the competitive coordination of ligands, acid anions, and water molecules around the central atom are not shown [3, p.765; 5, p.680]. To solve these problems as complexing agentswe have chosen zinc nitrate since by the change in the nature of organic ligands it is convenient to judge their ability to complexation. In connection with the above,the purpose of this work were the synthesis of monotype ligand complex compounds of zinc nitrate with acetamide and nicotinic acid and the establishment of the composition, personality methods for coordinating organic ligands and studying the thermal behavior of new compounds [4, p.430; 14, p.1950].

Methods and materials. For the synthesis of coordination compounds, we chose the most efficient mechanochemical method, since it does not require scarce organic solvents. The synthesis procedure was carried out according to [11,12].

A complex compound of composition Ca(C₁₅H₃₁COO)₂ CH₃CONH₂ CS(NH₂)₂ 2H₂O mol) thiocarbamide in a ball mill 100 ml, at room temperature for 30 minutes. The product yield is 89.7%. A mixed-ligand complex compound of the composition Ca(C₁₇H₃₃COO)₂ CH₃CONH₂ CO(NH₂)₂ H₂O was synthesized by intensive stirring of 0.6120 g (0.001 mol) of calcium oleate hemihydrate with 0.0591 g (0.001 mol) of acetamide and 0.0601 g (0.001 mol) urea in a ball mill 100 ml, at room temperature for 30 minutes.The yield of the final product is 96.3%. Thermal analysis was carried out on a derivatograph of the Paulik-Paulik-Erdey system at a rate of 10 deg/min and a weight of 0.1 g. A platinum crucible 7 mm in diameter without a lid served as a holder. Al₂O₃ was used as a reference [13].

Results and discussion.

Table 1.

Results of elemental analysis of mixed ligand palmitate, calcium oleate coordination compounds

Table 2.

Interplanar distances and relative intensities of lines of free molecules of acetamide, thiocarbamide, carbamide, their complexes with palmitate and calcium oleate

The heating curve of the compound Ca(C₁₅H₃₁COO)₂ CH₃CONH₂ CS(NH₂)₂ 2H₂O is characterized by seven endothermic effects at 130, 212, 269, 328, 362, 404, 760 °C and five exothermic effects at 305, 343, 450, 510 , 587 °C. The nature of these thermal effects is related to the stepwise decomposition of the complex. In temperature ranges 80-132, 132-240, 240-300, 300-320, 320-335, 335-350, 350-380, 380-430, 430-480, 480-570, 570-650, 650-790оС the weight loss is 2.20; 5.39; 8.70; 1.74; 0.43; 1.74; 2.00; 6.96; 26.09; 30.36; 0.51; 3.04%.The total weight loss in the range of 80-790°C according to the TG curve is 93.16%. Fourteen endothermic effects were found on the heating curve of Ca(C17H33COO)2 CH3CONH2 CO(NH2)2 H2O at 70, 120, 158, 177, 200, 214, 360, 374, 382, ​​415, 422, 570, 600 740°C and eleven exothermic effects at 233, 263, 333, 350, 495, 662, 683, 710, 780, 795, 843°C. The first endoeffect corresponds to the removal of one water molecule. The appearance of subsequent thermal effects is due to the decomposition and combustion of the thermolysis products of the complex. In temperature ranges 60-110, 110-130, 130-165, 165-185, 185-208, 208-220, 220-250, 250-290, 290-340, 340-355, 355-365, 365-378 , 378-390 390-418 418-440 440-560 560-580 580-640 640-670 670-700 700-730 730-760 760-790 790-820 -860оС weight loss, respectively, is 0; 2.20; 3.42; 2.74; 2.73; 2.73; 4.11; 2.33; 4.38; 4.79; 2.05; 2.05; 1.37; 2.05; 1.37; 2.05; 2.74; 4.79; 38.36; 4.11; 0.68; 2.74; 2.74; 2.05; 1.64; 0.10; 0.00%. The total weight loss in the temperature range of 60-860°C according to the thermogravimetry curve is 96.90%.

Таble 3.

Results of thermogravimetric analysis

Acetamide: 3377–ν_(NH2), 3191–2δ_(NH2), 1674–ν_(C=O), 1612–δ_(NH2), ν_(CO), 1394–ν_(CN), 1354–δ_(CH3), 1150–ρ_(NH2), 1047–ρ_(CH3), 1005–ν_(C‒C), 872–ν_(C‒C), 582–δ_(NCO) и 465–δ_(CCN).

Urea: 3448–ν_as(NH2), 3348–ν_s(NH2), 3263–2δ_(NH2), 1682–ν_(С=О), δ_(NH2), 1623–δ_(NH2), ν_(CO), 1450–ν_(CN), 1153, 1061–ρ_(NH2), 1005–ν_(CN), 788–2δ_(NH2), 583–δ_(NCO)and 557–δ_(NCN).

Thiocarbamide: 3365–ν_as(NH2), 3260–ν_s(NH2), 3167–2δ_(NH2), 1631–2δ_(NH2), δ_(НNC), 1431–ν_(CS), 1093–ν_(CN), 780–ρ_(NH2), 739–ν_(CS), 640–ν_(CS), δ_(NCS), 485–δ _(NCN) и 459–δ_(NCS).

Figure 1. IR absorption spectrum of the compound Ca(С₁₅Н₃₁СОО)₂ CH₃CONH₂ CS(NH₂)₂ 2H₂O

The IR absorption spectrum of a free acetamide molecule is characterized by several frequencies. Of these, at 1674 and 1666 cm^–1, bands are observed corresponding to the stretching vibrations of the C=O and C–N bonds. The first band decreases by 8 cm–1 when the acetamide molecule is coordinated through the oxygen atom of the carbonyl group. In this case, the value of the C–N bond frequency increases by 1394–1418 (7–8 cm^–1).

Three characteristic frequencies are observed in the IR absorption spectrum of a free thiocarbamide molecule at 739–ν(СS), 719–ν(CS), and 640 –δ(CS) cm^–1. In complex compounds of thiocarbamide, it is not possible to observe a change in the frequency value 739 cm^–1 –ν(CS), since it is overlapped by a wide band ν(СОО) of palmitate, oleate groups. Upon transition to the coordinated state in the low-frequency region of the spectrum, the frequencies of the thiocarbamide molecules at 739-719 and 640-629 cm^–1 decrease by 20 cm^–1 and 11 cm^–1, respectively. This is evidence of the coordination of the central atom through the sulfur atom. The thiocarbamide band decreases at 739 cm^–1 by 719cm^–1 when the thiocarbamide molecule is coordinated through the sulfur atom of the carbonyl group.

On the IR absorption spectrum of a free carbamide molecule, along with other frequencies, two bands are observed corresponding to the stretching vibrations of the C=O and C–N bonds. The first band decreases by (1682-1668) 14 cm^–1 when the urea molecule is coordinated through the oxygen atom of the carbonyl group. In this case, the value of the bond frequency (1450-1464) С‒N increases by 14 cm^‒1.

Conclusion. Synthesis conditions were developed, and two mixed-amide coordination compounds of palmitate and calcium oleate with acetamide, thiocarbamide, and urea were isolated in the solid state. The composition, individuality, and thermal properties of the resulting coordination compounds have been established.

The thermal behavior of the synthesized compounds was established by the method of derivatographic analysis. The intermediate products of thermolysis were obtained and the composition of the compounds was established. Endothermic effects observed during heating can be caused by such physical phenomena as melting, evaporation, change in the crystal structure, or chemical reactions of dehydration, dissociation. Transformations that are accompanied by exothermic effects when heated are much less common: these are oxidation processes and some structural changes.

References:

1. Sulaimankulov K.S. Urea compounds with inorganic salts. - Frunze: Ilim, 1976. -223 p.
2. Mamytov T.A. Studies of the interaction of lactates and citrates Mg, Mn(II), Fe(II), Co(II) with carbamide, thiocarbamide and nicotinamide.: Dis. – Candidate of Chemical Sciences. - Osh: 1999. - 150 p.
3. Interaction of thiourea and urea with mineral salts: Collection of articles Acad. Nauk Kirghiz. SSR. Institute of non-org-and physical. Chemistry - Frunze: Ilim. 1965. -96 p.
4. Imanakulov B.I. Interaction of acetamide with inorganic salts. Bishkek: Ilim, 1976. -204 p.
5. Khojaev O.F., Azizov T.A., Parpiev N.A. Studies of coordination compounds of divalent metals with acetamide \\ J. Sib. "Coordination chemistry", M., 1977. V.3. No. 10. S.1495-1502.
6. Meldebekova S.U., Azizov T.A. Pseudoamide complex compounds of nickel (II) acetate // Uzbek chemical journal. Tashkent, 2002, No. 5. pp. 23-28.
7. Direct synthesis of coordination compounds. Ed. acad. NAS of Ukraine Skopenko V.V. Kiev: Vent, 1997, -175 p.
8. Prishible P. Complexons in chemical analysis. M.: IL, 1960, S. 175-304.
9. Klimova V.A. Fundamentals of the micromethod for the analysis of organic compounds. Moscow: Chemistry, 1967. - 19 p.
10. Zhebentyaev A.I., Zhernosek A.K., Talut I.E. Analytical chemistry. Chemical methods of analysis. -Minsk: New knowledge, 2011. -542 p.
11. Bazhenova L.N. Quantitative elemental analysis of organic compounds. – Yekaterinburg: 2008. 356 p.
12. Yakimov I.S., Dubinin P.S. Quantitative x-ray phase analysis. -K.: IPK SFU, 2008. -25 p.
13. Gabbott P. (ed.) Principles and Applications of Thermal Analysis. – Singapore: Wiley-Blackwell, 2008. -480 p.