ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2011, Vol. 56, No. 8, pp. 1243–1249. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © E.E. Martsinko, L.Kh. Minacheva, A.G. Pesaroglo, I.I. Seifullina, A.V. Churakov, V.S. Sergienko, 2011, published in Zhurnal Neorganicheskoi Khimii,
2011, Vol. 56, No. 8, pp. 1313–1319.
COORDINATION
COMPOUNDS
Bis(citrato)germanates of Bivalent 3d Metals (Fe, Co, Ni, Cu, Zn):
Crystal and Molecular Structure of [Fe(H2O)6][Ge(HCit)2] · 4H2O
E. E. Martsinkoa, L. Kh. Minachevab, A. G. Pesarogloa, I. I. Seifullinaa,
A. V. Churakovb, and V. S. Sergienkob
a Mechnikov National University, ul. Dvoryanskaya 2, Odessa, 65025, Ukraine
b Kurnakov Institute of General and Inorganic Chemistry, Leninskii pr. 31, Moscow, 119991 Russia
Received March 29, 2010
Abstract—In continuation of a systematic study of bis(citrate)germanates, we synthesized a number of heteꢀ
rometallic germanium(IV) and
[M(H2O)6][Ge(HCit)2] H2O, where M = Fe,
= 3 ( . The complexes were characterized by elemental analysis, Xꢀray diffraction, thermogravimetry, and
IR spectroscopy. The Xꢀray diffraction analysis of compound
10.091(4) = 11.126(4) = 10.996(4) = 100.966(6)
= 0.0561 for 2266 reflections with > 2
3d
metal complexes based in citric acid (H4Cit) with the molecular formula
⋅
n
n
= 4 ( ; Co, = 2 (II ; Ni, = 2 (III ; Cu, = 1 (IV ; Zn,
I
)
n
)
n
)
n
)
n
V)
I
was performed. Crystals are monoclinic,
= 1212.1(8) Å3
= 4, space group 21/
is composed of centrosymmetric octahedral
a =
n,
Å,
b
Å,
c
Å
(
,
I
β
°
,
V
,
Z
P
R
1
I
σ
). Compound
I
complexes— [Ge(HCit)2]2– anions and [Fe(H2O)6]2+ cations—and crystallization water molecules. Strucꢀ
tural units in compound I are combined by a hydrogen bond system.
DOI: 10.1134/S0036023611080171
The hitherto studied heterometallic coordination water. The mixture was heated up to 80–90 С under
°
compounds can be classified into two basic groups. continuous stirring, until the reagents were completely
The first group comprises heteronuclear complexes in dissolved. The resulting transparent solution (pH 1.5–
which several metal atoms, both of the same and difꢀ 2.0) was concentrated on a water bath to 100 mL (~2.0 h)
ferent types, are incorporated, and a ligand acts as a and cooled.
bridge. In this case, complexes are formed if the ligand
At the second stage, a precisely weighed portion of
is sufficiently extended to prevent steric hindrances for
FeSO4
Ni(CH3COO)2
(for IV), or Zn(CH3COO)2
saturated solution of bis(citrato)germanic acid (20.0 mL,
0.002 mol) at the molar ratio Ge : Fe(Co, Ni, Cu, Zn) =
1 : 1 under continuous stirring until complete dissoluꢀ
tion. The mixtures were stirred for 5.0 min without
heating and filtered. The resulting solutions (pH =
4.0–5.0) were allowed to stand at room temperature
for crystallization. Light yellow (
green (III), blue (IV), or white (
tated from the corresponding solutions in 1–2 days
were filtered off on a Schott glass filter, washed with
⋅
7H2O (for
I
), Co(CH3COO)2
·
4H2O (for II),
H2O
V) was added to a
chelation of the groups at the different ends of its molꢀ
ecule. A heteronuclear complex of this type—barium
bis(citrato)germanate—was studied by us earlier [1].
The second group comprises the complexes in which a
polydentate ligand coordinates a metal atom of only
one type, whereas a metal atom of another type with its
own coordination sphere is incorporated into an indeꢀ
pendent counterꢀion. These compounds are of interꢀ
est from the viewpoint of both their structural features
and practical application as efficient catalysts and preꢀ
cursors [2]. Mononuclear metal complexes containing
a complex anion or cation are used as initial comꢀ
pounds for the synthesis of such cationic–anionic
complexes.
·
4H2O (for III), Cu(CH3COO)2
H2O (for
·
·
I
), pink (II), light
V
) crystals precipiꢀ
cold water, and dried at room temperature (20
crystals of [Fe(H2O)6][Ge(НCit)2] 4H2O ) suitable
for Xꢀray diffraction analysis were obtained by adding
an equal volume of acetonitrile to the corresponding
solution. The yield of the products was 80–85%.
°С). The
⋅
(I
The objective of the present work is to synthesize
heterometallic complexes on the basis of bis(citꢀ
rate)germanate and some
3d
ꢀmetal cations (Fe2+,
Co2+, Ni2+, Cu2+, Zn2+), and to determine their propꢀ
Elemental analysis. The content of germanium and
other metals was determined by inductively coupled
plasma atomic emission spectroscopy on a Perkin
Elmer Optima 2000 DV spectrometer, and the analysis
for carbon and hydrogen was performed with the use
erties, structure, and type.
EXPERIMENTAL
Synthesis of compounds I–V. At the first stage, of a semiautomated C,N,H analyzer. The content of
GeО2 (1.046 g, 0.01 mol) and citric acid monohydrate hydrates was calculated from thermogravimetric
(4.2 g, 0.02 mol) were introduced into 400 mL of hot curves.
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