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AZ9RBAYCAN KIMYA JURNALI № 3 2017
39
UDC 546.719
SYNTHESIS AND STUDY OF Re(V) COMPLEX COMPOUNDS WITH
BENZIMIDAZOLE
M.M.Agaguseynova, F.D.Gudratova
Azerbaijan State Oil and Industry University minim baku@yahoo.com Received 24.06.2016
The complex compounds Re(V) with benzimidazole have been synthesized using [ReO(Ph3P)2Cl3] and H2[ReOBr5]. The structures and compositions obtained complexes have been determined on the base of IR spectroscopy and elemental analysis. The monodentant coordination of benzimidazole with Re(V) has been approved.
Keywords: synthesis, rhenium, benzimidazole, structure, coordination complex.
In 1958 D.Hodgkin and his colleagues discovered that unlike the nucleotides of the nucleic acid, the bases of the Bi2-nucleotide are not purine or pyrimidine, but it is a cobalt complex of 5,6-dimethylbenzimidazole. This invention, as well as well-known facts of the presence of biochemically bound metals in azole systems (hemoglobin, cytochrome, etc.) led to the development of synthetic, physico-chemical and structural studies of metal complexes with azoles and their derivatives.
The complexes of a large group of azoles and their benzene analogues with chromium-, molybdenum-, and tungsten-hexacarbonyls are known [1]. The onium type complex compounds for palladium with benzimidazole - [(BI)H]2[PdBr4] were also obtained. But the complexes of rheni-um(V) with benzimidazole are not described in the literature.
Synthesis of [ReO(BI)2Cl]Cl complex compounds
Synthesis of complex compounds was carried out as the following. 1.50 g (0.0018 mole) of trans-[ReO(Ph3P)2Cl3] and 0.64 g (0.0054 mole) benzimidazole were dissolved in diglyme and heated in a flask equipped with a reflux condenser, at the melting temperature of the solvent in inert atmosphere (argon) within 5 hours. In 24 hours the red-brown crystals were settled from brown solvent, filtrated and washed with the main solvent, isopropyl alcohol and ether.
The obtained compound is soluble in water, acetonitrile, methanol and DMSO.
Found, %: Re 27.97, C 38.85, H 2.96, N
12.70. For ReOC21H18N6Cl3. Calculated, %: Re 28.08, C 38.04, H 2.72, N 12.68.
Localized place of coordination bond was determined on the basis of infrared spectroscopic (IR) analysis. Disappearance of the absorption bands characteristic for C=C and C=N stretched valet vibrations in 1700-1800 cm-1 shows the elimination of electron density delocalization inside the imidazole ring in the transition from non coordinated ligand to complex combination.
High frequency slip (20-30 cm-1) and strengthening of intensity of absorption bands corresponding to stretching vibrations of azole rings (1450-1500 cm-1) makes possible to prove that the coordination of the rhenium atom with the ligand proceeds by benzimidazole pyridine nitrogen atoms [2, 3]. The spectra of the complex appearance of intense absorption bands at 748, 620 and 420 cm-1 related to the stretching vibrations of Re-H bond and stability of valency vibrations of NH-group in 3400-3100 cm-1 also confirms this fact. 320 and 306 cm-1 absorption bands refer to the vibration frequencies of Re-Cl bond located in trans-position to each other [4, 5], and 930 cm-1 absorption bands show presence of Re=O bond.
Lack of absorption bands 510-530 cm V(P-Caryl) in the spectrum of complex compound testifies substitution of all triphenylphos-phine ligands to benzimidazole. Study electron absorption spectrum (EAS) of water and methanol solutions of benzimidazole and complex compounds showed that absorption bands 35760, 36600, 37100, 38700 cm-1 - a bands characterize
-1
long wave transfer tc^-tc*. But "p" band at 39800 and 40700 cm-1 related to single configurated transfer in benzimidazole spectrum is exposed to hypsochromic slip (Figure 1). "p" slip of V band is more significant than "a" strip slipping. It is a fact, if to consider the coordination of benzimid-azole due to the tertiary nitrogen atom.
Fig. 1. EAS UV spectra benzimidazole and rhenium(V) complex: 1 - [ReOCBIbCya, 2 - [(BI)H]2[ReOBr5], 3 - [ReO](BI)2Br], 4 - benzimidazole.
In the visible area of the compound absorption bands of 21500 cm-1 and 17800 cm-1 appear characteristic oxychloride surround of rhenium atom in +5 oxidation degree.
Based on generalization of the above mentioned complex compound [ReO(BI)3Cl2]Cl can be shown in the following structure (Scheme1):
O
Scheme 1
Such structure is confirmed by the value of the molar conductivity. Molar conductivity
12 1
for water solution was 109.5 Om- •cm •mole- , which is characteristic to binary electrolytes.
Onium type compounds for rhenium(V) oxohalides with some azole series members such as antipirin, amidopirin, analgyn, 2-mer-captoimidazole, phenanthroline have been obtained. For the first time [(BI)H]2[ReOBr5] has been obtained.
Synthesis of complex compound [(BI)H]2[ReOBr5]
0.783 g BI has been added into 25 ml saturated solution [(BI)H]2[ReOBr5] by constantly stirring. Synthesis was carried out within 0.5 hours. Then brick-red crystalline precipitate was filtrated and washed several times with the main solvent, isoproyl alcohol and dried with ether. The substance undergoes to hydrolysis even in the presence of a small amount of water. It is insignificantly soluble in polar organic solvents and dissolvable in nonpolar solvents.
The composition of the complex compound is confirmed by elemental analysis, EAS and IR spectroscopic methods. Found, %: Re 22.20, C 19.83, H 1.44, N 6.34. For ReOC14H16N4Br5. Calculated, %: Re 22.14, C 20.00, H 1.67, N 6.87.
In the IR spectrum of the onium complex compounds at 3380 cm-1 presence of extended absorption bands indicates to existence of the protonated nitrogen atom in the heterocycle and formation of external spherical cation [(BI)H]+. In the area of 953 clearly pronounced peak indicates Re=O bond saving.
The thermal mobility of the compound was studied to determine the possibility of the transfer of external spherical ligand to inner sphere of rhenium complex Andersen regrouping. On thermograms it is clearly seen that endo-thermic effect has been watched at 3800C temperature. This phenomena is connected with the transition of external spherical benzimidazole into interval sphere of ligand surrounding of rhenium atoms. Analogical fact is observed in the study of phenanthroline complex of rhenium(V). In an inert atmosphere thermal synthesis was conducted at a certain transition temperature and in the solid phase transition (3800C), as a result a
M.M.AGAGUSEYNOVA, F.D.GUDRATOVA
41
dark green compound [ReO(BI)2Br3] dissolving in polar organic solvents has been obtained.
Results of elemental analysis confirm the above composition. Found, %: Re 27.51, C 24.33, H 1.58, N 8.11. For ReOC14H12N4Br3. Calculated, %: Re 27.43, C 24.78, H 1.77, N 8.25.
IR spectra of this compound is perfectly similar to IR spectrum of [ReO(BI)3Cl2]Cl, which confirms the transition of BI into internal spherical rhenium surrounding. The difference is observed in the low-frequency range, in contrast to the absorption bands 320 and 306 cm-1 in complex [ReO(BI)3Cl2]Cl, an absorption bands at 288, 268 and 236 cm-1 in the complex [ReO(BI)2Br3] refer to the stretching vibrations of the Re-Br (Figure 2).
S'10"
S'10": 0.8
0.6
0.4
0.2
3 - 1
30000
25000
20000
15000 v ,
Fig. 2. EAS benzimidazole and rhenium(V) in so-lutio n in the visible area: 1 - ^OstBIbCblCl -right >"-axis, 2 - [(BI)H]2[ReOBr5] - right >"-axis, 3 - [ReO](BI)2Br3] - left >>-axis.
General characteristics of the EAS synthesized solvents, is the presence of absorption bands, characterizing the chromophore group of benzimidazole in the UV area and benzimidaz-ole transition into their complex is proved by the slip of bands "a" and "p" (Figure 2).
However, in the border of UV-area and in the visible region of the spectrum of each compound individual view appears which is related to the transition of electrons in the metal-ligand system and depends on the nature, the quantity, the position of substituents in space. The spec-
trum of the compound [(BI)H]2[ReOBr5] (18960, 21900, 25200, 32200 and 34160 cm-1) is also characteristic for oxobromides complexes of rhenium(V); when substituting two molecules of benzimidazole with two ligands [ReO(BI)2Br3] and three molecules of ligands with three benzimidazole [ReO(BI)3Cl2]Cl spectra of these compounds are quite different in the electron transition region of metal-ligand and may be used to identify test compounds.
Considering all the above mentioned, the connection structure of [ReO(BI)2Br3] can be represented as following (Scheme 2):
O
Br,
,Br
Re
Br '
Br
BI
Scheme 2
As multi-bound oxygen in oxohalide system has stronger trans-effect that is why bound of benzimidazole in trans-position to oxygen is more probable. This assumption is similar to the formation of [ReO(BI)3Cl2]Cl compounds.
References
1. Hannack M., Kamenzin S., Kamenzin C. Subramanian L.R. Synthesis and properties of axi-ally disubstituted monomeric and oligomeric phthalocyaninato ruthenium(II) compounds// Synthesic Metals. 2000. V. 110. No 2. P. 93-103.
2. Агагусейнова М.М., Джаббарова Н.Э. Координационные соединения переходных металлов в катализе. Баку: Элм, 2006. 245 с.
3. Агагусейнова М.М., Джаббарова Н.Э. Комплексы переходных металлов с молекулярным кислородом. Баку: Элм, 2012. 201с.
4. Толбин А.Ю., Томилова Л.Г., Зефиров Н.С. Несимметрично замещенные фталоцианины: синтез и модифицирование структуры //Успехи химии. 2007. Т. 76. № 7. С. 732-744.
5. Дудник А.С., Иванов А.В., Томилова Л.Г., Зефиров Н.С. Синтез и исследование фталоци-аниновых комплексов рения // Коорд. xимия. 2004. Т. 30. № 2. С. 120-124.
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Re(V)-UN BENZiMiDAZOLLA KOMPLEKS BiRLO§MOLORINiN SiNTEZi УЭ TODQiQi
M.M.Agahüseynova, F.D.QUdratova
trans-[ReO(Ph3P)2Cl3] Va H2[ReOBr5] tatbiq edarak reniumun benzimidazolla komplekslari sintez edilmi§dir Alinan koordinasion birla§malarin qurulu^u va tarkibi iQ spektroskopiya va element analizi naticalari asasinda tayin edilmi§dir. Sintez olunmu§ komplekslarda fiziki-kimyavi tadqiqatlar asasinda benzimidazolun monodentant koordinasiyasi müayyan edilmi§dir.
Agar sözlar: sintez, renium, benzimidazol, struktur, koordinasiya kompleksi.
СИНТЕЗ И ИЗУЧЕНИЕ КОМПЛЕКСНЫХ СОЕДИНЕНИЙ Re(V) С БЕНЗИМИДАЗОЛОМ
М.М.Агагусейнова, Ф.Д.Гудратова
Используя соединения рения - транс-[ReO(Ph3P)2Cl3] и H2[ReOBr5] синтезировали комплексы бензимидазола. Структура и состав полученных координационных соединений установлены на основе ИК-спектроскопических данных и результатов элементного анализа. В синтезированных комплексах на основании совокупности физико-химических исследований определена монодентатная координация бензимидазола.
Ключевые слова: синтез, рений, бензимидазол, состав, координационный комплекс.
