Co(II), Ni(II) and Cu(II) complexes with 1-(4-hydroxyphenyl)-1H-1,2,4- triazole

Article abstract of DOI:10.1023/B:RUCO.0000030162.64191.66

New complexes of Co(II), Ni(II), and Cu(II) with 1-(4-hydroxyphenyl)-1H-1, 2,4-triazole (L) of the composition ML₂(H₂O) ₂(NO₃)₂ · nH₂O (M = Co(II), n = 3; M = Ni(II), n = 0; M = Cu(II), n =

Full text of DOI:10.1023/B:RUCO.0000030162.64191.66

Russian Journal of Coordination Chemistry, Vol. 30, No. 6, 2004, pp. 413–418. Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 6, 2004, pp. 442–447.
Original Russian Text Copyright © 2004 by Lavrenova, Ikorskii, Sheludyakova, Naumov, Boguslavskii.
Co(II), Ni(II) and Cu(II) Complexes
with 1-(4-Hydroxyphenyl)-1H-1,2,4-Triazole
L. G. Lavrenova, V. N. Ikorskii, L. A. Sheludyakova, D. Yu. Naumov, and E. G. Boguslavskii
Nikolaev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 3, Novosibirsk, 630090 Russia
Received April 2, 2003
Abstract—New complexes of Co(II), Ni(II), and Cu(II) with 1-(4-hydroxyphenyl)-1H-1,2,4-triazole (L) of the
composition ML2(H2O)2(NO3)2 · nH2O (M = Co(II), n = 3; M = Ni(II), n = 0; M = Cu(II), n = 0) were synthe-
sized and studied by photoelectron and IR spectroscopy, magnetochemistry, thermogravimetry, and X-ray pow-
der diffraction analysis. The type of µeff(T) relationship suggests that paramagnetic centers in the Co(II) chlo-
ride and Cu(II) nitrate and bromide complexes are involved in antiferromagnetic exchange interactions. The
exchange energy values were estimated by the molecular field method.
1,2,4-Triazole and its derivatives constitute a prom- coordination. The structure of the Cu(II) complex with
ising class of ligands that are widely used in the synthe-
sis of various complexes [1]. Three nitrogen atoms in a
cycle specify their extensive coordinating capabilities,
which makes it possible to produce complexes with dif-
ferent structures and properties. Since 1,2,4-triazoles
do not contain substituents in positions 1, 2 of the side
chain or substituents capable of coordinating, they are
mainly coordinated to a metal as bidentate bridging
ligands through atoms N1, N2 of a cycle (less frequently
through the N2, N4 atoms) and give bi-, tri-, and polynu-
clear complexes. The trinuclear complexes can form
both linear and triangular exchange clusters [1, 2]. The
metal complexes with 1,2,4-triazoles have peculiar
magnetic properties. They exhibit antiferro- and ferro-
magnetic exchange interactions between paramagnetic
centers. Of particular interest are the iron(II) complexes
with 1,2,4-triazole and its 4-substituted derivatives that
'
1-ethyl-1,2,4-triazole of the composition CuL2 Cl2 was
determined in [7] by X-ray diffraction analysis. In this
complex, Cu(II) has the square-planar coordination
realized by the nitrogen atoms of two monodentate tri-
azoles and by two chlorine atoms. This coordination is
completed to a tetragonal bipyramid due to additional
contacts Cu···Cl and gives a layered motif.
The synthesis and study of the cyanate and thiocy-
anate complexes of Mn(II), Fe(II), Co(II), Ni(II),
Cu(II), and Zn(II) with 1-phenyl-1,2,4-triazole that had
different compositions depending on the synthesis con-
ditions were described in [8]. In these complexes, the
ligand has monodentate coordination, while some thio-
cyanate complexes have polynuclear structures due to
the bridging NCS groups. The complexes of chlorides
and bromides of Mn(II), Co(II), Ni(II), Cu(II), Zn(II),
Cd(II), and Hg(II) with 1-vinyl- and 1-vinyl-3-amino-
1,2,4-triazoles were synthesized and studied in [9]. The
authors of this paper suggested that these ligands are
coordinated in the monodentate mode through the N4
atom of triazole cycle in compounds with the general
formula ML2A2.
show spin transition 1A1
5T2 accompanied by ther-
mochromism [3, 4].
The introduction into a side chain of the 1,2,4-triaz-
ole ligand of substituents capable of coordinating
results in the formation of mononuclear complexes
containing metal cycles or polynuclear complexes,
where 1,2,4-triazole derivatives have both bidentate
bridging and bidentate chelate coordination. In this
case, the ligand acts as a tridentate bridge. Such type of
coordination was found in the Cu(II) trifluoromethyl-
sulfonate, nitrate, or perchlorate complexes with 3-
acetylamino-1,2,4-triazolate ion [5].
It was of interest to synthesize and study compounds
of Co(II), Ni(II), and Cu(II) with the 1,2,4-triazole
derivative that contains more composite substituent in
position 1, namely, 1-(4-hydroxyphenyl)-1H-1,2,4-tri-
azole (L), of the following structure [10]:
N
The 1-substituted 1,2,4-triazoles are the least stud-
ied ligands of this class. The authors of [6] reported the
N
N
'
synthesis of ML2 Cl2 complexes from chlorides of
some metals of the first transition series and 1-vinyl-, 1-
allyl-, 1-propargyl-, or 1-(butadiene-1,3-yl)-1,2,4-triaz-
oles (L'). They suggested the tetrahedral structures of
these complexes and the monodentate type of the ligand
OH
1070-3284/04/3006-0413 © 2004 åÄIä “Nauka /Interperiodica”

414
LAVRENOVA et al.
Table 1. Results of elemental analysis of M(II) complexes (M = Co, Ni, Cu) with L
Content (found/calcd), %
Compound
Empirical formula
C
H
N
M
CoL2(H2O)2(NO3)2 · 3H2O
CoL2(H2O)2Cl2
(I)
(II)
C16H24CoN8O13
31.7/32.3
42.2/39.4
35.4/35.2
41.3/40.5
35.6/35.2
40.5/40.5
35.0/35.2
45.4/45.5
41.1/40.9
4.5/4.1
3.3/3.7
3.6/3.4
3.7/3.4
3.8/3.3
3.3/3.4
2.7/2.6
3.6/3.9
3.8/3.4
18.4/18.8
18.4/17.2
20.1/20.7
20.8/21.0
20.3/20.5
17.5/17.7
15.2/15.4
25.2/25.1
25.2/26.0
10.2/9.9
12.1/12.1
10.9/10.9
10.9/11.0
11.3/11.6
13.2/13.4
11.8/11.6
9.0/9.3
C16H18Cl2CoN6O4
NiL2(H2O)2(NO3)2
NiL2(H2O)2(NCS)2
CuL2(H2O)2(NO3)2
CuL2(H2O)Cl2
(III) C16H18N8NiO10
(IV)
(V)
C18H18N8NiO4S2
C16H18CuN8O10
C16H16Cl2CuN6O3
(VI)
CuL2Br2
(VII) C16H14Br2CuN6O2
(VIII) C24H22N12NiO2S2
(IX)
NiL2(Pz)2(NCS)2
CoL2(Pz)2(NCS)2
C22H22CuN12O2
9.7/9.8
EXPERIMENTAL
Bomem-102 Fourier spectrometer in the range of 200–
500 cm–1.
Hydrates of the metal nitrates and chlorides, CuBr2,
and 1-(4-hydroxyphenyl)-1H-1,2,4-triazole used in the
synthesis were purchased from ACROS Company.
X-ray powder diffraction analysis was performed on
a Philips-PW1700 diffractometer (CuKβ radiation,
graphite monochromator, scintillation detector with
amplitude discrimination in the range of 2θ angles from
5° to 65° with the 0.02° step and exposure time of 20 s
per point, at room temperature).
The EPR spectra of powders of the complexes were
recorded on a Varian E-109 radiospectrometer
equipped with analog-digital signal converter and an
original software for accumulation and preliminary
processing of the spectra. The studies were carried out
in the Q range. In order to calibrate the working fre-
quency, the spectra of the investigated compounds were
recorded together with a standard, i.e., the diphenylpic-
rylhydrazyl powder (g = 2.0036). The EPR data given
below were obtained by modeling of the theoretical
spectra with Sinfonia (Bruker) program.
Synthesis of CoL2(H2O)2(NO3)2 · 3H2O (I),
CoL2(H2O)2Cl2 (II), NiL2(H2O)2(NO3)2 (III),
CuL2(H2O)2(NO3)2 (V), CuL2(H2O)Cl2 (VI), CuL2Br2
(VII). A specimen (2 mmol) of one of the metal salts
(Co(Ni)(NO3)2 · 6H2O, 0.58 g; CoCl2 · 6H2O, 0.48 g;
Cu(NO3)2 · 3H2O, 0.48 g; CuCl2 · 2H2O, 0.34 g; CuBr2,
0.45 g) was dissolved with stirring in 7–10 mol of hot
isopropanol solution. A weighed portion of a ligand
(0.32 g, 2 mmol) was dissolved in 30–35 ml of a mix-
ture of isopropanol–acetone (4 : 1) on heating and stir-
ring and then was added to a solution of the metal salt.
After removing most part of the solvent and cooling the
reaction mixture, the precipitates of complexes formed.
Synthesis of NiL2(H2O)2(NCS)2 (IV). Specimens
of Ni(NO3)2 · 6H2O (0.87 g, 3 mmol) and NH4NCS
(0.91 g, 12 mmol) were joinly dissolved in 3–5 ml of
water, while the ligand sample (0.48 g, 12 mmol) was
dissolved in 40 ml of a mixture of isopropanol–acetone.
The obtained solutions were heated and mixed together.
A transparent dark green solution that formed was con-
centrated on a water bath with stirring. Complex IV
precipitated when the solvent was almost evaporated
and the solution was cooled.
The TG curves were obtained in air using the quartz
cells and Paulik-Paulik-Erdey derivatograph (at
2.5 K/min heating rate and with Al2O3 standard).
RESULTS AND DISCUSSION
The complexes with L were isolated from the iso-
propanol–acetone mixture (4 : 1) at the metal : ligand
molar ratio equal to 1 : 1 and the metal concentration
~0.05 mol/l. Such a metal to ligand ratio is determined
by the limited solubility of L. When a stoichiometric
ratio of M and L was used in the syntheses, a mixture
of two phases (of the desired complex and a ligand) was
produced. All compounds, except for ëuL2Br2, contain
The precipitates of complexes I–VII were filtered
off and washed with isopropanol and ethanol. The
metal content was determined by trilonometric titration
after decomposition of compounds in a mixture of con-
centrated HClO4 and H2SO4 acids (2 : 1).
The results of the elemental analysis of complexes water, which is confirmed by the elemental analysis and
I–VII are presented in Table 1. The magnetic suscepti- IR data. The amount of water was found from TG and
bility of polycrystalline samples of the complexes was elemental analysis data that agree well. The tempera-
measured by the Faraday method in the temperature tures at which the beginning of the mass loss is
interval 78–300 K. The diffuse reflection spectra were observed are 60–70°ë. The TG curve of complex I has
recorded on a Unicam-700A spectrophotometer. IR two steps corresponding to dehydration process; the
absorption spectra were taken on a Specord 75IR spec- first step lies in the temperature range of 60–100°ë; the
trophotometer in the range of 400–4000 cm–1 and on a second step is in the interval 100–140°ë. The first step
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Co(II), Ni(II) AND Cu(II) COMPLEXES
415
Table 2. Patameters of diffuse reflection spectra of M(II) complexes with L (M = Co, Ni, Cu)
Compound
Color
λmax, nm
∆ × 10–3, cm–1
CoL2(H2O)2(NO3)2 · 3H2O
(I)
pink
510
1190
510
620
1220
390
630
1085
380
630
890
610
695
695
9.5
CoL2(H2O)2Cl2
(II)
pink
9.3
9.2
NiL2(H2O)2(NO3)2
NiL2(H2O)2(NCS)2
(III)
(IV)
green-blue
blue
11.2
CuL2(H2O)2(NO3)2
CuL2(H2O)Cl2
CuL2Br2
(V)
(VI)
(VII)
blue
green
dark green
most likely occurs due to the elimination of three crys-
The spectra of all complexes have in the region of
tallization, water molecules, whereas the second step 3200–3460 cm–1 the bands ν(ç2é) and the bands
δ(ç2é) in the region of 1620 cm–1.
corresponds to removal of two water molecules from
coordination sphere of the complex.
The low-frequency regions (200–500 cm–1) of IR
spectra of all complexes contain the bands at 230–
280 cm–1 that are produced by the stretching vibrations
of the metal–nitrogen bond. These positions of the
bands corresponding to the ν(M–N) vibrations are typ-
ical of the complexes with 1,2,4-triazoles [12, 13]. The
bands in the frequency interval 350–370 cm–1 and 450–
490 cm–1, which are lacking from the spectrum of a free
L, correspond to ν(M–O). The assignment of the bands
due to the stretching vibrations of the M–Cl and M–Br
bonds proved to be difficult. One can assume that the
bands ν(M–ël) are partially or fully overlapped by the
ν(M–N) bands, while the band ν(M–Br) lies in the
region below 200 cm–1, which is confirmed by the data
in [14].
IR spectra of a free ligand contain the coordination-
sensitive bands in the range of 1470–1520 cm–1 that are
produced by the stretching-deformation vibrations of
the 1,2,4-triazole ring. The band at 1599 cm–1 is due to
the stretching vibrations of the phenyl ring. A broad
structurized band produced by ν(ëç) of the triazole
and phenyl cycles and ν(éç) are observed in the range
of 2600–3400 cm–1.
In IR spectra of all complexes, the bands due to the
stretching-deformation vibrations of the 1,2,4-triazole
ring are shifted toward high frequencies by 4–11 cm–1,
which is typical of the complexes of this class and sug-
gests coordination of the nitrogen atoms of the ring by
the metal. Moreover, the band at 1599 cm–1 correspond-
ing to the phenyl ring vibrations is shifted by 5–12 cm–1
toward the high frequency region. Such a significant
influence of the ligand coordination on the position of
the band due to the phenyl ring vibrations indirectly
indicates coordination of L by the metal through the N2
atom of a heterocycle.
The diffuse reflection spectra of complex I (Table 2)
have two bands that can be assigned to the d–d transi-
tions: 4T1g
4T1g (P) (ν3, 19600 cm–1) and 4T1g
4T2g (ν1, 8400 cm–1) in the distorted octahedral field of
the ligands. The relevant spectra of complex II contain
three bands due to d–d transitions: 4T1g
19600 cm–1), T1g
4T1g (P) (ν3,
4
4A2g (ν2, 16100 cm–1), and
The spectra of the nitrate complexes I, III, and V
contain bands at 1380 cm–1 that correspond to the vibra-
tioans ν3 of the NO–3 ion. The intense band due to the
4T1g
4T2g (ν1, 8200 cm–1) in octahedral field of the
ligands. Complex III exhibits three bands that can be
assigned to the following d–d transitions: 3A2g
3T1g
stretching vibration ν(CN) of the NCS– ion in complex
IV (2125 cm–1) shifts with respect to ν(CN) in the spec-
trum of KNCS (2050 cm–1) toward high-frequency
region by 75 cm–1, which indicates that the thiocyanate
ion is coordinated to a metal through the nitrogen atom
[11].
(P) (ν3, 25600 cm–1), 3A2g
3T1g (F) (ν2, 15900 cm–1),
3
and A2g
3T2g (ν1, 9220 cm–1). The spectrum of
complex IV has three bands of d–d transitions:
3A2g
3T1g (P) (ν3, 26300 cm–1), A2g
3T1g (F)
3
(ν2, 15900 cm–1), and 3A2g
3T2g (ν1, 11220 cm–1).
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 30 No. 6 2004

416
LAVRENOVA et al.
Thus, the number and positions of the bands in the conclude that in reactions (1) and (2), the pyrazole mol-
diffuse reflection spectra of compounds I–IV (Table 2) ecules replace the water molecules in the inner sphere
suggest pseudo-octahedral structure of the coordination of complexes IV and V and give the mixed-ligand com-
cores of Co(II) and Ni(II) in these complexes. The split- plexes VIII and IX. When the pink-colored
ting parameters for Co(II) complexes (I and II) were CoL2(H2O)2Cl2 (II) is stored at 100°ë in a drier to a
calculated provided that ν1 = 8.8 Dq (Table 2). Com- constant weight, its color is changed to blue color, and
plex II has the value of ∆ which is lower than that for its mass loss corresponds to the elimination of two
complex I. This is an evidence of the replacement of the water molecules according to the equation:
nitrate ion in the inner sphere of Co(II) by the chloride
CoL2(H2O)2Cl2 = CoL2Cl2 + 2H2O.
(3)
ions. Conversely, when going from complex III to
complex IV, this parameter increases, which occurs in
the case of the nitrate ion replacement in the inner
sphere of Ni(II) by the thiocyanate ion.
When the CoL2Cl2 (II') sample is placed in a humid
atmosphere, the amount of water in its composition
increases to 3.5 molecules and CoL2(H2O)2Cl2
·
1.5H2O (II'') is formed. This specimen was sealed in a
quartz tube to prevent water loss and the χ–1(T) function
was plotted (Fig. 1). The hole ~1 mm in diameter was
made in a tube and the specimen was evacuated to a
constant mass, and the indicated dependence was
recorded again. The data obtained suggest that the color
is changed as a result of the change in the octahedral
surrounding of Co(II) in complexes II and II' to the tet-
rahedral surrounding in an anhydrous complex II'.
The diffuse reflection spectra of Cu(II) complexes
contain the band that can be assigned to d–d transitions
2Eg
2T2g in a distorted octahedral field of the
ligands.
In order to indirectly confirm the coordination core
composition in complexes I–V, the reactions were car-
ried out between the solutions of complexes
NiL2(H2O)2(NCS)2 or CuL2(H2O)2(NO3)2 in isopro-
panol and a solution of pyrazole (Pz) in ethanol:
The effective magnetic moments were calculated
from the formula µeff = (8χT)1/2, while for complexes
II', II'', V–VII, we used the formula µeff = (8χ(T –
θ))1/2, where χ is the molar magnetic susceptibility cor-
rected for the atomic diamagnetism. The values of µeff
for Co(II) and Ni(II) complexes (Table 3) are typical of
the high-spin configurations d7 and d8, respectively, and
of configuration d9 for Cu(II) complexes in the octahe-
dral filed of the ligands. The temperature dependences
of a reversible magnetic susceptibility for complexes
II', II'', and V–VII follow the Curie–Weiss low χå =
C/(T – θ) (Fig. 1). The parameters C and θ, as well as
µeff for complexes II', II'', and V–VII at 300 K and for
complexes I, III, and IV at 290 K are listed in Table 3.
The negative values of the Weiss constants (θ) indicate
the antiferromagnetic exchange interactions in com-
plexes II', II'', V, and VII. We estimated the values of
the exchange energies (Table 3) by the molecular filed
method [15] using the formula θ = 2zJS(S + 1)/3k,
where J is the parameter of exchange between para-
magnetic centers, z is the number of the nearest para-
magnetic centers, S is the metal ion spin, k is the Bolt-
zman constant.
The EPR spectrum of complex V has typical form of
line for the samples with the axial anisotropy of the g-
factor without hyperfine structure (HFS). The anisotro-
pic width of the line is specified by unresolved HFS
from the copper nuclei. The interpretation of the spec-
trum and its refinement through modeling with Sinfo-
nia program reveals the triaxial anisotropy of g-factor
and of the line widths: g1 = 2.055, g2 = 2.064, g3 =
2.314, W1 = 45 Gs, W2 = 35 Gs, W3 = 160 Gs. The aver-
age value of g-factor is 2.144. The form of the line does
not correspond to the Lorentzian or Gauss forms, which
occurs in the spectra with unresolved HFS. The
observed shifts in g-factors and the correlation between
the maximum shift in g-factor and the maximum line
NiL2(H2O)2(NCS)2 + 2Pz = NiL2(Pz)2(NCS)2, (1)
(VIII)
CuL2(H2O)2(NO3)2 + 2Pz = CuL2(Pz)2(NO3)2. (2)
(IX)
The obtained mixed-ligand complexes VIII and IX
were isolated from a solution and studied by the ele-
mental analysis (Table 1).
The long-wave region of IR spectrum of complex
VIII does not contain the bands from the stretching
vibrations of the Ni–O bond, while IR spectrum of
complex IX has the bands due to the stretching vibra-
tions of both Cu–O and Cu–N bonds. Thus, one can
1/χ, cm–3 mol
1/χ, cm–3 mol
1
2
3
4
700
600
500
400
300
120
100
80
5
60
200
100
0
40
20
50
100
150
200
T, K
250
300
Fig. 1. The temperature dependence of the reversible mag-
netic susceptibility (1/χ) for (1) CuL (H O)Cl , (2)
2
2
2
CuL Br , (3) CuL (H O) (NO ) , (4) CoL Cl , and (5)
2
2
2
2
2
2
2
2
3 2
2
2
CoL (H O) Cl · 1.5H O.
2
2
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 30 No. 6 2004

Co(II), Ni(II) AND Cu(II) COMPLEXES
417
Table 3. The parameters of Curie–Weiss equation and µeff for complexes I, II', II'', III–VII
Compound
C, cm3 K/mol
θ, K
µeff, µB
–zJ, cm–1
CoL2(H2O)2(NO3)2 · 3H2O
CoL2(H2O)2Cl2 · 1.5H2O
CoL2Cl2
(I)
4.80 (290 K)
4.86
(II'')
(II')
(III)
(IV)
(V)
2.934
2.816
–4.5
–6.2
1.3
1.7
45.75
NiL2(H2O)2(NO3)2
NiL2(H2O)2(NCS)2
CuL2(H2O)2(NO3)2
CuL2(H2O)Cl2
3.06 (290 K)
3.27 (290 K)
1.84
0.423
0.412
0.466
–1.8
0
2.5
0
(VI)
(VII)
1.82
CuL2Br2
–11.0
1.93
15.0
width indicate that the coordination surrounding of the by two L molecules coordinated in a monodentate
Cu2+ ion is the extended octahedron.
mode and by two bridging and one terminal bromine
atoms (Fig. 2). Such a structure of the CuL2Br2 com-
plex is supported by the magnetochemistry and EPR
data.
The averaging of g-factors and HFS caused by the
exchange interaction is commonly observed in the
magnetoconcentrated phase. In this case, the averaged
values of g-factors are typical of noninteracting ions,
i.e., the chains of parallel coordination polyhedra of the
Cu2+ ion are involved in interaction. Asynchronous
change in the g-factor shift (g1, g2) and in line width
(W1, W2) suggests that the equatorial plane of the coor-
dination polyhedron contains one or two atoms with
magnetic nucleus (obviously, nitrogen atom).
The above data make it possible to conclude that in
complexes I–V, the coordination polyhedra have octa-
hedral structures formed by two nitrogen atoms (of
molecules L) coordinated in the monodentate fashion,
two water molecules and the corresponding two anions.
It is most likely that L is coordinated to the metal
through N2 of a heterocycle. Complexes I, III, and V
have MN2O4 coordination cores (M = Co, Ni, Cu); the
coordination core of complex II is ëÓN2O2Cl2, while
that of complex IV is NiN4O2. The coordination poly-
hedron of complex VI is, probably, the square pyramid
(the CuN2OCl2 core). In equatorial plane, Cu(II) atom
coordinates two L molecules and two chloride ions, its
coordination number is increased to five by the oxygen
atom of water molecule. Complex VII has binuclear
The EPR spectrum of complex VI has a triaxial
anisotropy of g-factor and line width. The spectral
parameters after modeling are: g1 = 2.031, g2 = 2.088,
g3 = 2.275, W1 = 50 Gs, W2 = 50 Gs, W3 = 100 Gs, the
average g-factor being 2.131. In this case, the aniso-
tropy of g-factor and line width is less than in complex
V. These parameters can be explained by the coordina-
tion of the Cl– ions that have the nuclear magnetic
moment (nuclear spin 3/2) and by the nonparallel
arrangement of the exchange-related coordination
polyhedra of the Cu2+ ion in the crystal lattice of the
complex. Unfortunately, the EPR data do not provide
unambiguous conclusion (probably, both facts are
effective).
C
N
O
N
H
Complex VII has the EPR spectrum in the form of a
broad symmetric line with gav = 2.14 and line width
~1000 Gs. This compound is suggested to have the
polymeric structure, which determines the exchange
interactions between the Cu2+ ions.
N
C
Cu
Br
Br
Cu
The data of X-ray powder diffraction analysis of
CuL2Br2 are given in Table 4. The DICVOL program
was used to find the CuL2Br2 unit cell parameters: a =
12.142 Å, b = 10.124 Å, c = 10.911 Å, α = 106.33°, β =
91.51°, γ = 109.94°, space group P1 or P1. The calcu-
lated unit cell volume is 1198.81 Å3, ρ(calcd) =
1.512 g/cm3, Z = 2, which agrees well with the experi-
mental value (1.5 g/cm3) found by the procedure [16].
The analysis of the unit cell parameters suggests the
dimeric structure of CuL2Br2. Each Cu atom has the tri-
angular bipyramidal coordination polyhedron formed
Fig. 2. The structure of Cu L Br proposed on the basis of
X-ray powder diffraction data.
2
4
4
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418
LAVRENOVA et al.
Table 4. Interplane distances (d) and intensities (I) for
CuL2Br2* calculated from experimental diffractogram
2. Virovets, A.V., Podberezskaya, N.V., and Lavrenova, L.G.,
Zh. Strukt. Khim., 1997, vol. 38, no. 3, p. 532.
3. Gutlich, P., Hauser, A., and Spiering, H., Angew. Chem.,
Int. Ed. Engl., 1994, vol. 33, no. 20, p. 2024.
d, Å
I, %
d, Å
I, %
11.3807
9.1028
8.2263
7.4964
6.0501
4.9813
4.9169
4.8671
6.0
100.0
7.8
4.1718
3.3697
3.1930
2.8751
2.6902
2.4949
2.3715
2.0883
24.8
5.2
4. Lavrenova, L.G. and Larionov, S.V., Koord. Khim.,
1998, vol. 24, no. 6, p. 403.
5. Ferrer, S., Haasnoot, J.G., Reedijk, J., et al., Inorg.
Chem., 2000, vol. 39, no 5, p. 1859.
6. Attaryan, O.S., Asratyan, G.V., Kinoyan, F.S., et al.,
Koord. Khim., 1989, vol. 15, no. 5, p. 707.
7. Slovokhotov,Y.L., Struchkov,Y.T., Polinsky, A.S., et al.,
Cryst. Struct. Commun., 1981, vol. 10, no. 2, p. 577.
11.5
10.1
3.2
3.5
10.5
29.6
3.9
4.4
9.4
8. Donker, C.B., Haasnoot, J.G., and Groeneveld, W.L.,
19.6
3.7
Transition Met. Chem., 1980, vol. 5, no. 6, p. 368.
* Reflections with the relative intensity exceeding 3% are listed.
9. Domnina, E.S., Skvortsova, G.G., Makhno, L.I., and
Chipanina, N.N., Zh. Obshch. Khim., 1988, vol. 58,
no. 10, p. 2331.
10. Foces-Foces, C., Cabildo, P., Claramunt, R.M., and
Elguero, J., Acta Crystallogr., Sect. C: Cryst. Struct.
Commun., 1999, vol. 55, no. 7, p. 1160.
11. Nakomoto, K., Infrared and Raman Spectra of Inorganic
and Coordination Compounds, Chichester: Wiley, 1986.
12. Lavrenova, L.G., Larionov, S.V., Ikorskii, V.N., and She-
ludyakova, L.A., Zh. Neorg. Khim., 1987, vol. 32, no. 8,
p. 1925.
structure due to the bridging function of one of bromide
ions (the CuBr3N2 core) (Fig. 2). Thus, unlike unsubsti-
tuted 1,2,4-triazole and its 4-R derivatives, L (that has a
substituent in position 1 of triazole) is coordinated as a
monodentate ligand and mainly forms the mononuclear
compounds.
ACKNOWLEDGMENTS
13. Lavrenova, L.G., Baidina, I.A., Ikorskii, V.N., et al., Zh.
Neorg. Khim., 1992, vol. 37, no. 3, p. 630.
We are grateful to European Science Foundation
(ESF) and Deutsche Forschungsgemeinschaft for
financial support and to Professor F. Gutlich for his
concern shown to this work.
14. Oglezneva, I.M., Lavrenova, L.G., and Larionov, S.V.,
Zh. Neorg. Khim., 1984, vol. 29, no. 6, p. 1476.
15. Smart, J., Effective Field Theories of Magnetism, Phila-
delphia: Sounders, 1966.
REFERENCES
16. Bronshtedt-Kupletskaya, E.M., Opredelenie udel’nogo
vesa mineralov (Determination of the Specific Gravity
of Minerals), Moscow: Akad. Nauk SSSR, 1951, p. 96.
1. Haasnoot, J.G., Coord. Chem. Rev., 2000, vols. 200–202,
p. 131.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 30 No. 6 2004