ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2015, Vol. 60, No. 6, pp. 729–735. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © N.A. Skorik, M.M. Filippova, E.I. Bukhol’tseva, V.S. Mal’kov, I.A. Kurzina, 2015, published in Zhurnal Neorganicheskoi Khimii, 2015, Vol. 60, No. 6,
pp. 806–812.
PHYSICAL METHODS
OF INVESTIGATION
Cobalt(II) and Copper(II) Complexes with Carboxylic Acids,
Imidazole, and 2ꢀMethylimidazole
N. A. Skorik, M. M. Filippova, E. I. Bukhol’tseva, V. S. Mal’kov, and I. A. Kurzina
Tomsk State University, pr. Lenina 36, Tomsk, 634050 Russia
eꢀmail: Skorikninaa@mail.ru
Received September 26, 2014
Abstract—The compositions of [MIm(MeIm)x]L complexes synthesized by the reaction of cobalt(II) and
copper(II) fumarates ML · nH2O with imidazole (Im) and 2ꢀmethylimidazole (MeIm) were determined. The
thermal decomposition of the salts was analyzed, and the pyridine nitrogen atom of imidazole and the oxygen
atoms of carboxyl anions were shown to participate in complexation using electronic absorption spectra and
IR spectra. The composition and stability of cobalt(II) and copper(II) imidazolatesuccinate complexes in an
aqueous solution were determined photometrically and spectrophotometrically, and their higher stability in
comparison with monoligand complexes was demonstrated.
DOI: 10.1134/S0036023615060157
Interest in the chelates of biogenic elements (Fe, thesis of succinate dihydrates МC4H4O4
·
2H2O (М =
Zn, Cu, Mn, Mo, and Co) with organic ligands of difꢀ Mn2+, Fe2+, Co2+, Cu2+, Zn2+) by the reaction between
the corresponding
succinic acid and sodium hydroxide and the synthesis
of iron(III) fumarate Fe2(C4H2O4)2(OH)2 · 2H2O are
dꢀmetal sulfate and a mixture of
ferent chemical natures and bioactivities is currently
kept undiminished. Most of the processes occurring in
biological systems involve the interaction of metal ions
with several ligands, so the synthesis of mixedꢀligand
complexes and the study of their properties and strucꢀ
ture are of particular interest. In many cases, the
ligand incorporated into such a complex exhibits bioꢀ
activity, which is not typical of it in the free state. Thus,
the new zinc complexes with nitroimidazole, adamanꢀ
tine, and nitrofuran derivatives were established to
have more pronounced antimicrobial activities than
the initial ligands [1]. The metal ions in mixedꢀligand
complexes become less toxic and gain the ability to
catalyze various biochemical processes. The frequent
appearance of synergism for the ligands in mixedꢀ
ligand complexes with two bioactive ligands is also
noteworthy. For this reason, biometal complexes can
be used as a basis to create new medicines, bioactive
supplements, biocatalysts, etc.
described in [3, 4].
Succinic acid (H2Suc) and fumaric acid (H2Fum
)
are known to form complexes with transitionꢀmetal
ions in solution. The survey of the stability of copꢀ
per(II) succinate complexes [CuSuc] (logβ1 = 3.02) and
copper(II) hydrogen succinate complexes [CuHSuc]+
(logβ11 = 1.99) is given in [5]. The copper(II)–
fumaric acid system is found to contain only one preꢀ
dominant complex [CuFum] (logβ1 = 2.35) [6].
Coordination compounds of dꢀmetal ions on the
basis of nitrogenꢀcontaining heterocycles, in particuꢀ
lar, azoles, have efficient pharmacological activity and
participate in key vital processes. Imidazole derivaꢀ
tives hold a great place in the field of medicinal chemꢀ
istry. For example, 2ꢀmethylimidazole C4H6N2 is used
as an initial material for the synthesis of antiꢀinfective
agents. Some mixedꢀligand complexes of metal salts
with imidazole derivatives (1ꢀethylimidazole, 1ꢀmethꢀ
ylimidazole, etc.) have also been prepared. Syntheses
with 2ꢀmethylimidazole (L) and copper(II) bromide
from ethanol solutions yielded complexes of different
compositions [7]: [CuL2Br2] was prepared from neuꢀ
Moreover, the coordination compounds of dꢀeleꢀ
ments with organic ligands containing various donor
atoms are good models for studying the mutual effect
of ligands in complexes. Such ligands, which are of
both theoretical and practical interest, may be carboxꢀ
ylic acids, amino acids, oxyacids, vitamins, and
azoles. For example, succinic and fumaric acids and
tral solutions; (HL)2[CuBr4] · H2O was prepared from
some their salts with dꢀcations are applied in different
solutions in the presence of HBr at the ratio M : L = 1 : 2
and pH 1 (according to IR spectra, the ligand is in the
outer sphere of the complex; and (HL)2[Cu2Br6] was
prepared from solutions with pH 2–3, where HL+ is
the outerꢀsphere cation. The composition and strucꢀ
fields, such as the production of food supplements,
beverages, and medicinal, cosmetic, veterinary, and
agricultural preparations, and fumarates are widely
used as blood plasma substitutes. The physicochemiꢀ
cal properties of succinates, hydrogen succinates, and ture of dimeric, monomeric, and polymeric copꢀ
fumarates of some metals were studied in [2]. The synꢀ per(II) benzimidazole complexes synthesized by the
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