SYNTHESIS AND STRUCTURE OF A COORDINATION COMPOUND BASED ON NICKEL (II) FORMAT AND LEAD (II) METACHRESOXYACETATE

ABSTRACT

This article presents the method of synthesizing a heterometallic polynuclear coordination compound based on nickel (II) formate and lead (II) methacreoxyacetate and the results of X-ray phase analysis to determine its structure. The results obtained from the X-ray phase analysis were also proven to be reproducible structure using the FullProf program

АННОТАЦИЯ

В данной статье представлен метод синтеза гетерометаллического полиядерного координационного соединения на основе формиата никеля (II) и метакреоксиацетата свинца (II) и результаты рентгенофазового анализа для определения его структуры. Результаты, полученные в результате рентгенофазового анализа, также оказались воспроизводимыми с использованием программы FullProf

Keywords: nickel (II) formate, lead (II) methacreoxyacetate, elemental analysis, X-ray phase analysis, FullProf

Ключевые слова: формиат никеля (II), метакрилоксиацетат свинца (II), элементный анализ, рентгенофазовый анализ, FullProf

Introduction. Synthesis of new mixed-ligand coordination compounds with heterometallic bilayers and determination of their properties is of great importance in the world. Among the substances of this group, the presence of substances with luminescent, stimulating, magnetic properties makes it possible to use them widely in various sectors of the economy. In addition, coordination compounds of this group have the property of forming separate clusters due to the presence of a large number of metal atoms, and are also used as carriers of various substances in living organisms.

Cresoxyacetate and its derivatives have been found to have immunomodulatory properties, reduce microbes in the body, protect the liver and have many other biological activities [1,2].

A new mononuclear complex [Ni(h²-ООССМе₃)(h²-2,2'-bipy)(h²-С₆Н₆NO)] new heterometallic complex [(h¹-С₆H₇NO)Ni₅Cu₅(µ₃-OH)₆(µ-OOCCMe₃)6(h¹-ООССМе₃)2(µ₃,h²-С₆Н₆NО)₄ (µ,h²-С₆Н₆NО)₂] was found to be formed, this compound is close to pivalate and trifluoroacetate Сo10 and Ni10 complexes by its structure.

Figure 1. Heterometallic complex containing nickel-copper

Nickel (II) pivalates are characterized by the formation of binuclear complexes with a "luminescent" structure, similar to Сo(II) and Cu(II), with the composition Ni₂L₂(µ-O₂CCMe₃)₄, where L = Py, 2,3-lutidine, NEt₃, 2,5-lutidine, 2-picoline, 2-ethylpyridine [3], 3,5-dimethylpyrazole [4], as well as dinuclear coordination compounds in which metal atoms are connected by three bridging ligands, in which two pivalate anions and water molecules act as ligands: Ni₂(µ-OH₂)(µ-Piv)₂(Piv)₂L₄, where L = HPiv [5-7], Py, 3,4-lutidine, N-nitroethoxynicotinamide [8], 3,5-dimethylpyrazole.

For example, the corresponding dinuclear [Ni₂(µ-OH₂)(Piv)₄(HPiv)₄] isostructural [Co₂(µ-OH₂)(Piv)₄(HPiv)₄], which can be obtained in various ways, unlike its cobalt-capsulating counterpart will have ferromagnetic type spin-spin interaction rather than antiferromagnetic exchange. It should also be noted that the complexes [Ni₂(µ-OH₂)(Piv)₄(HPiv)₄], [Ni₂(µ-OH₂)(Piv)₄(Py)₂(HPiv)₂], [Ni₂(µ-OH₂)(Piv)₄(Py)₄], the exchange effect changes twice: initially ferromagnetic [Ni₂(µ-OH₂)(Piv)₄(HPiv)₄] antiferromagnetic [Ni₂(µ-OH₂)(Piv)₄(Py)₂(HPiv)₂] and then back to ferromagnetic [Ni₂(µ-OH₂)(Piv)₄(Py)₄]. {M₂(µ-OH₂)(µ-Piv)₄}, where M = Co, Ni, such changes of magnetic moments in binuclear complexes indicate that the magnetic properties depend on the nature of the central metal, and the distribution of metal ions to the local surroundings on subtle differences in the structures of the complexes.

When considering the polynuclear complexes of nickel(II), the metal cation is considered to have an octahedral ring in all compounds.The main issue of the stoichiometry of complexones is aimed at determining the specificity of binding of the complexone with the complexing agent.

In the reaction of two, chelating, different ligands, the intermediate metal cation and the total dentinity of which is greater than the capacity of the complex former, the equilibrium may be shifted towards the formation of polynuclear heteroligand compounds.

The presence of binuclear compounds М₂En₂Edta₄,, where M is Ni²⁺, Co²⁺, Mn²⁺, in aqueous solutions was proved by spectrophotometry, rN-metry and cryoscopy methods [9].

In [10], the structure of a bihydrogen complex compound of nickel (II) consisting of an azacyclam ligand and an oxalate anion as a bridge was determined using the method of X-ray structural analysis. As a result of studying the magnetic properties of a number of complexes of this type, it was found that antiferromagnetic interaction between metal ions is observed, and it was proved that the exchange integral varies from 11.8 cm^-1 to 25.6 cm^-1 (Fig. 2).

Figure 2. Structure of bihedral complex containing [(NiL₂)₂(ox)](ClO₄)₂]

In the K₂[Ni(NO₃)₄] compound presented in [11], the chain is oriented along the b axis (Fig. 3). K⁺ ions are placed between the chains and connect the chains parallel to the ab axis. Nickel atoms are connected to the chain due to nitrate groups of the syn anti type located in the octahedral environment of the metal atoms.

Figure 3. Structure of [Ni(NO₃)₄]^2- chain in K₂[Ni(NO₃)₄] crystal structure

Another compound with a unique structure was reported in [12] and is rubidium nitrate nickelate with Rb₃[Ni₂(NO₃)₇] composition, which has a ribbon structure. It consists of an infinite number of [Ni₂(NO₃)₇]_n^3n-  composition zigzag bands directed along the α axis and Rb⁺ cations between them. Nickel atoms are located at the nodes of the band, and each of them has a distorted octahedral framework consisting of oxygen atoms belonging to two ends (mono- and bidentate) and three bridging nitrate groups.

Research Methodology. The following salts were used for the synthesis of complex compounds: lead (II) acetate, m-cresoxyacetic acid, nickel (II) sulfate and formic acid. The used organic solvents were also purified and dried by known methods.

The synthesis of the starting materials was carried out using the following methods: An alkali solution prepared in a 1:2 mol ratio was added to the metal salt solution. The resulting precipitate was washed by decantation until foreign ions disappeared. A salt solution was formed by adding meta-cresoxyacetic acid to the purified lead hydroxide precipitate.

Pb(CH₃COO)₂ + 2NaOH = Pb(OH)₂↓ + 2CH₃COONa

Pb(OH)₂↓ + 2 CH₃-C₆H₄-O-CH₂-COOH = (CH₃-C₆H₄-O-CH₂-COO)₂Pb

Nickel (II) formate was obtained using the following method:

NiSO₄ + 2NaOH = Ni(OH)₂↓ + Na₂SO₄

Ni(OH)₂↓ + 2HCOOH = 2(HCOO)₂Ni + H₂O

The synthesis of the complex compound was carried out according to the following method: 0.01 mol nickel formate was dissolved in 20 ml of water. In another beaker, 0.02 mol lead(II) methacreoxyacetate was dissolved in 20 ml of a 1:1 mixture of water:acetonitrile by heating in a hot water bath (at a temperature of 50-55 C). Then Ni(II) drop wise over the formate solution, lead of a hot solution of methacreoxyacetate was added and the mixture was evaporated for 4 h until the volume was reduced by a factor of 1.5. The resulting solution was left for 2 days. The resulting powdery substance was dissolved in a mixture of  5 ml of distilled water and 5 ml of alcohol and left for 72 hours to recrystallize. The yield of the mass of the obtained substance compared to the mass of the initial substance was 88.3%.

Analysis and results. The elemental composition of the substances formed in all reaction processes was determined (Table 1).

Table 1.

Elemental analysis and some physical properties of synthesized primary substances and complex compounds

In order to prove the individuality of the crystal lattice of the coordination compound synthesized with Pb(II) methacreoxyacetate of Ni(II) formate, X-ray phase analysis of the original and synthesized coordination compound was carried out and diffractograms were compared. It was found that the interplanar distances and intensity of the synthesized compound did not match (Fig. 4).

Figure 4. X-ray pattern of the complex compound [Ni(HCOO)₂∙2Pb(CH₃-C₆H₄-OCH₂COO)₂] compared with the starting materials

In order to prove the structure of the synthesized compounds, a structural analysis was carried out on a modern diffractometer of the Malvern Pananalytical company, Empyrean, based on X-ray scattering at the Scientific Research Institute of Nuclear Physics of the Republic of Uzbekistan.

Table 2 and Fig. 5 show the crystallographic characteristics and X-ray structural analysis results obtained from the processing of diffractogram results using the Fullprof program.

Table 2.

[Ni(HCOO)₂∙2Pb(CH₃-C₆H₄-OCH₂COO)₂] crystallographic data and details of the structure of the complex

a)                                                                             b)

Figure 5. [Ni(HCO₂)₂∙2(C₉H₉O₃)₂Pb] structural form (a) and structure of the molecule (b) of the complex compound

Conclusion. In order to prove the individuality of the crystal lattice of the coordination compound synthesized with manganese methacreoxyacetate of Ni(II) formate was analyzed using X-ray phase analysis. The data obtained in the analysis of radiographs showed that the synthesized complex has unique properties that cannot be found in the crystallographic database. As can be seen from the given structure, the coordination in the synthesized compound is connected through the nickel (II) ion and the oxygen atoms of the c, -resoxyacetate carbonyl group. In this case, the coordination number of the ion is equal to 6, and the geometry of the coordination node is an octahedron.

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