ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2007, Vol. 52, No. 9, pp. 1395–1401. © Pleiades Publishing, Inc., 2007.
Original Russian Text © L.S. Skorokhod, I.I. Seifullina, V.G. Vlasenko, I.V. Pirog, V.V. Minin, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 9,
pp. 1491−1497.
COORDINATION
COMPOUNDS
Cobalt(II), Nickel(II), and Copper(II) Complexes
with Schiff Bases, Derivatives
of 1-Amino-8-hydroxynaphthalene-2,4-disulfonic Acid
L. S. Skorokhoda, I. I. Seifullinaa, V. G. Vlasenkob, I. V. Pirogb, and V. V. Mininc
a Mechnikov National University, Dvoryanskaya ul. 2, Odessa, 65026 Ukraine
b Research Institute of Physics, Rostov State University, pr. Stachki 194, Rostov-on-Don, 344104 Russia
c Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
Received December 22, 2006
Abstract—Five new cobalt(II), nickel(II), and copper(II) complexes with Schiff bases have been synthesized.
The Schiff bases have been prepared by the condensation of monopotassium 1-amino-8-hydroxynaphthalene-
2,4-disulfonate with benzoin (L1) or 2-hydroxy-1-naphthaldehyde (L2). The compounds have been identified
and studied by elemental analysis, X-ray diffraction, thermogravimetry, measurements of magnetic susceptibility
and electrical conductivity, and IR, ESR, and diffuse reflectance spectroscopy. The dimeric (with oxo bridges)
structure of the Co(II) complex with L1 has been additionally confirmed by the EXAFS method.
DOI: 10.1134/S0036023607090148
Synthesis of complexes I and II. Solutions of L1
(1.65 g, 0.003 mol) in an ethanol–methanol (50 mL +
70 mL) mixture and divalent nickel or cobalt (for I and
II, respectively) chloride hexahydrate (0.71 g, 0.003 mol)
in ethanol (20 mL) were mixed and refluxed in a water
bath for 2 h. The resulting precipitates of complexes I
and II were separated by filtration, washed with etha-
nol, and dried at room temperature above anhydrous
calcium chloride to a constant weight.
The present study is intended as a continuation of
our works devoted to the development of different
methods of the synthesis and investigation of the com-
position and structure of coordination compounds of
bivalent cobalt, nickel, and copper with the products of
condensation of aminonaphthalene derivatives and aro-
matic carbonyl-containing compounds [1–6].
The products of condensation of aminonaphtha-
lene(di)sulfonic acids, which are polydentate ligands,
play a special role among diverse chelating Schiff
bases. When studying the complex formation of Cu(II)
Synthesis of Schiff base L2. Solutions of 1,8,2,4-
ahKsHs'n (7.14 g, 0.02 mol) in ethanol (60 mL) and
2-hydroxy-1-naphthaldehyde (3.44 g, 0.02 mol) in etha-
nol (50 mL) were preliminarily mixed, and anhydrous
sodium acetate (6 g, 0.07 mol) was added. The resulting
solution was refluxed in a water bath for 1 h. The result-
ing dark brown precipitate of L2 was subjected to the
same procedures as those for the synthesis of com-
plexes I and II. The melting point of the product is
185°C.
with
1-amino-8-hydroxynaphthalene-2,4-disulfonic
acid (1,8,2,4-ahKsHs'n) and benzoin (L1) derivatives,
we synthesized a square-planar complex in which the
sulfo groups are not involved in coordination [5]. It was
of interest to reveal whether the sulfo groups will be
bonded when Cu(II) is replaced by Co(II) or Ni(II) (for
which complexes with the bonds between the complex-
forming ion and the oxygen atom of the sulfo group
were prepared [6]) and to elucidate how the change in
the ligand system of L2 (1,8,2,4-ahKsHs'n and
2-hydroxy-1-naphthaldehyde derivative) will affect the
composition and structure of the Co(II), Ni(II), and
Cu(II) complexes.
For C21H14KNO8S2 anal. calcd. (%): C, 49.32; H,
2.74; N, 2.74; S, 12.52; K, 7.63.
Found (%): C, 49.61; H, 2.60; N, 2.56; S, 12.68; K,
7.31.
Synthesis of complexes III–IV. Reaction mixtures
consisting of L2 (1.53 g, 0.003 mol) in ethanol (50 mL)
and crystal hydrate of nickel(II), cobalt(II), or cop-
per(II) chloride (0.003 mol; 0.71, 0.71, or 0.51 g,
EXPERIMENTAL
The Schiff base—condensation product of 1-amino-
8-hydroxynaphthalene-2,4-disulfonic acid (1,8,2,4-
ahKsHs'n) and benzoin [5]—was used as a ligand (L1) respectively) in ethanol (15 mL) were refluxed in a
for the synthesis of Ni(II) and Co(II) complexes (I and water bath for 1 h. Precipitates of complexes III–V
II, respectively; Table 1).
formed upon cooling down were subjected to the same
1395