Synthesis and study of N-(1-phenylethylidene)-N-(4H-1,2,4-triazol-4-yl) amine, N'-(4H-1,2,4-triazol-4-yl)benzamidine, and cobalt(ii), nickel(ii), and copper(ii) complexes based on these ligands

Article abstract of DOI:10.1007/s11172-008-0260-z

Methods were developed for the synthesis of complexes of Co^II, Ni^II, and Cu^II nitrates and chlorides with N-(1-phenylethylidene)-N-(4H-1,2,4-triazol-4-yl)amine (L¹) and N-(4H-1,2,4-triazol-4-yl)benzamidine (L

Full text of DOI:10.1007/s11172-008-0260-z

Russian Chemical Bulletin, International Edition, Vol. 57, No. 9, pp. 1931—1943, September, 2008
1931
Synthesis and study of Nꢀ(1ꢀphenylethylidene)ꢀ
Nꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)amine, N´ꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)benzamidine,
and cobalt(II), nickel(II), and copper(II) complexes based on these ligands
E. V. Lider,a,b E. V. Peresypkina,a K. A. Volkova,c E. V. Abramova,c Yu. G. Shvedenkov,a V. N. Ikorskii,a,d
†
L. A. Sheludyakova,a A. I. Smolentsev,a and L. G. Lavrenovaa,b
aA. V. Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences,
3 prosp. Akad. Lavrentieva, 630090 Novosibirsk, Russian Federation.
Fax: +7 (383) 330 9489. Eꢀmail: ludm@che.nsk.su
bNovosibirsk State University,
2 ul. Pirogova, 630090 Novosibirsk, Russian Federation
cA. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences,
1 ul. Favorskogo, 664033 Irkutsk, Russian Federation
dInternational Tomography Center, Siberian Branch of the Russian Academy of Sciences,
3A ul. Institutskaya, 630090 Novosibirsk, Russian Federation
Methods were developed for the synthesis of complexes of CoII, NiII, and CuII nitrates and
chlorides with Nꢀ(1ꢀphenylethylidene)ꢀNꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)amine (L1) and N´ꢀ(4Hꢀ1,2,4ꢀ
triazolꢀ4ꢀyl)benzamidine (L2). The CoII and NiII complexes have a linear trinuclear structure.
The CuII complexes are polynuclear. Both ligands are coordinated to the metal ions in
a bidentateꢀbridging mode through the N(1) and N(2) atoms of the heterocycle. In all comꢀ
pounds, the coordination polyhedron can be described as a distorted octahedron. The molecular
and crystal structure of the [Ni3(L1)6(EtOH)2(H2O)4](NO3)6•2EtOH•4H2O complex was esꢀ
tablished.
Key words: synthesis, coordination compounds, 1,2,4ꢀtriazoles, structure, UV—Vis and
IR spectroscopy, magnetochemistry, Xꢀray diffraction study.
1,2,4ꢀTriazoles have attracted considerable interest as
ligands.1 Unsubstituted 1,2,4ꢀtriazole (HTrz) and its deꢀ
rivatives (RTrz) with free positions 1 and 2 are coordinated
to metals predominantly in a bidentateꢀbridging mode
through the N(1) and N(2) atoms of the heterocycle. The
first compounds with this coordination mode were syntheꢀ
sized and structurally characterized in the 1960s. These
were the polynuclear complex Cu(HTrz)Cl2 and the triꢀ
nuclear complex [Ni3(HTrz)6(H2O)6](NO3)6•2H2O.3,4
Since that time a large number of polynuclear metal comꢀ
plexes with 1,2,4ꢀtriazoles were synthesized1 (see, for exꢀ
ample, M5(RTrz)12).
2
† Deceased.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1897—1908, September, 2008.
1066ꢀ5285/08/5709ꢀ1931 © 2008 Springer Science+Business Media, Inc.

1932
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
Lider et al.
Several types of linear trinuclear complexes, in which
pairs of adjacent metal ions are linked by triple bridges
through coordination by the N(1) and N(2) atoms of
1,2,4ꢀtriazoles, were documented. In all these compounds,
the coordination polyhedron of the central metal ion can
be described as a distorted octahedron (the MN6 coordiꢀ
nation unit). The terminal ions are also in an octahedral
environment due to the involvement of the N atoms of
monodentate triazole ligands and (or) the O atoms of waꢀ
ter molecules. Depending on the nature of the ligands,
the coordination units have the composition MN3O3
(type 1),5—7 MN4O2 (type 2),8,9 or MN5O (type 3).5,10 In
addition, triangular trinuclear MII complexes with RTrz
were described.11,12
It was of interest to extend the range of coordination
compounds with 4ꢀRTrz and to investigate their magnetic
properties. In the present study, we synthesized two new
1,2,4ꢀtriazole derivatives containing bulky substituents at
position 4, viz., Nꢀ(1ꢀphenylethylidene)ꢀNꢀ(4Hꢀ1,2,4ꢀtriꢀ
azolꢀ4ꢀyl)amine (L1) and N´ꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)ꢀ
benzamidine (L2). Methods were developed for the synꢀ
thesis of CoII, NiII, and CuII complexes with these ligands.
The compositions and structures of the coordination units
were determined, and the temperature dependences of
the effective magnetic moment for these compounds
were studied.
Results and Discussion
The polyꢀ or trinuclear structures of metal complexes
with 1,2,4ꢀtriazoles are responsible for their unusual magꢀ
netic properties. Studies of magnetic properties of these
complexes revealed both ferroꢀ and antiferromagnetic exꢀ
change interactions between paramagnetic ions.7—9,13,14
Of special interest are compounds of different iron(II) salts
with HTrz and its 4ꢀsubstituted derivatives with the comꢀ
position Fe(RTrz)nAm•pH2O, where A is a singly or douꢀ
bly charged anion, which is not involved in coordination;
Nꢀ(1ꢀPhenylethylidene)ꢀNꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)ꢀ
amine (L1) was synthesized by condensation of 4ꢀaminoꢀ
4Hꢀ1,2,4ꢀtriazole with acetophenone in the presence of
BaO as the dehydrating agent in ethanol (Scheme 1).
N´ꢀ(4Hꢀ1,2,4ꢀTriazolꢀ4ꢀyl)benzamidine (L2) was synꢀ
thesized by the reaction of 4ꢀaminoꢀ4Hꢀ1,2,4ꢀtriazole with
benzonitrile in liquid ammonia (Scheme 2).
n = 2, 3; m = 1, 2; p = 0—5. The thermally induced spin
The crossꢀpeaks indicative of dipoleꢀdipole interacꢀ
tions between protons of the phenyl and triazole rings are
absent in the homonuclear 2D NOESY spectra of L1 and
L2. The spectrum of L1 shows a weak crossꢀpeak correꢀ
sponding to interactions between protons of the methyl
1
transition A1
(the pink
5T2 accompanied by thermochromism
white color change) was observed in these
complexes.15,16 In most of these compounds, the spin tranꢀ
sition is sharp, and the plots μeff(T) show hysteresis.

Metal(II) complexes with 1,2,4ꢀtriazoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
1933
Scheme 1
Scheme 3
L = L1, M = Ni, n = 0 (1); M = Co, n = 2 (2);
L = L2, n = 2, M = Co (4), Ni (5)
Scheme 2
L = L1, M = Ni (3); L = L2, M = Co (6)
group and the triazole ring. This indicates that both comꢀ
pounds are E isomers.
The CoII, NiII, and CuII complexes with the ligands L1
and L2 were synthesized by the reactions of hot ethanolic
solutions of the corresponding metal salts and the ligands
according to Eqs (1)—(4) (Scheme 3, Table 1). Compꢀ
lexes 1—9 precipitated from hot ethanolic solutions.
A = NO3– (8), Cl– (9)
Solutions of the copper salts were acidified with the
corresponding acids to prevent reduction of Cu2+. The
[Ni3(L1)6(H2O)4(EtOH)2](NO3)6•2EtOH•4H2O comꢀ
Table 1. Elemental analysis data for the MII complexes with L1 and L2
Compound
Found
Calculated
Empirical formula
(%)
Cu
С
H
Co
N
Ni
[Ni3(L1)6(H2O)6](NO3)6 (1)
[Co3(L1)6(H2O)6](NO3)6•2H2O (2)
[Ni3(L1)6(H2O)6]Cl6 (3)
41.1
40.6
38.1
39.8
45.1
44.6
35.3
35.7
35.1
35.7
40.6
40.0
44.5
44.1
36.9
36.2
39.9
39.7
4.0
4.1
4.0
4.2
4.4
4.5
3.8
3.9
4.0
3.9
3.9
4.1
4.3
4.1
3.3
3.7
3.9
4.1
—
—
—
—
—
—
—
—
24.1
23.7
23.3
23.2
21.2
20.8
26.5
27.7
26.6
27.8
26.2
25.9
28.6
28.6
28.7
28.1
26.1
25.7
9.5
9.9
—
C60H72N30Ni3O24
C60H76Co3N30O26
C60H72Cl6N24Ni3O6
C54H70Co3N36O26
C54H70N36Ni3O26
C54H66Cl6Co3N30O6
C72H80Cl6N40Ni3O4
C18H22CuN12O8
9.7
9.8
—
10.7
10.9
—
[Co3(L2)6(H2O)6](NO3)6•2H2O (4)
[Ni3(L2)6(H2O)6](NO3)6•2H2O (5)
[Co3(L2)6(H2O)6]Cl6 (6)
9.4
9.7
—
9.4
9.7
—
10.5
10.9
—
[Ni3(L2)8(H2O)4]Cl6 (7)
9.2
9.0
—
[Cu(L2)2(H2O)2](NO3)2 (8)
[Cu(L2)2(H2O)2]Cl2 (9)
—
—
10.6
10.6
11.6
11.7
—
C18H22Cl2CuN10O2

1934
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
Lider et al.
plex was obtained (10) after prolonged storage of a dilute
ethanolic solution of nickel nitrate and the ligand L1.
The metalꢀtoꢀligand molar ratio used for the synthesis
of coordination compounds 1—3, 9, and 10 was 1 : 2; for
the synthesis of compounds 4, 5, and 8, 1 : 1; for the
synthesis of compounds 6 and 7, 1 : 3. The elemental
analysis of the phases prepared with the use of other M : L
ratios showed that these phases partially contain coordiꢀ
nation compounds with other compositions.
evidence that the nitrogen atoms of the heterocycle are
coordinated to the metal atoms. The IR spectra of all coꢀ
ordination compounds show one band in the region of
torsional vibrations of the heterocycle at 625—640 cm–1
(see Table 2). This spectral pattern is characteristic of the
bidentateꢀbridging coordination of 1,2,4ꢀtriazoles to metꢀ
al ions.170
The IR spectra of nitrate coordination compounds 1
and 2 show two bands at 1390—1300 cm–1 belonging to
–
The resulting coordination compounds are moderately
soluble in ethanol and water and are poorly soluble in
propanꢀ2ꢀol, acetone, and CHCl3.
vibrations of NO3 ions (see Table 2). The IR spectra of
coordination compounds 4, 5, and 8 have one intense band
at 1380—1370 cm–1. These data are indicative of the outꢀ
erꢀsphere coordination of the nitrate ion in these complexꢀ
es.18 The splitting of ν3(NO3) into two components is eviꢀ
dently attributed to hydrogen bonding with water moꢀ
lecules.
In the 3360—3200 cm–1 region, the IR spectra of the
coordination compounds show stretching bands of coordiꢀ
nated water molecules. In the same region, the spectra of
the coordination compounds with L2 have bands assigned
The main characteristic frequencies in the IR spectra
of the ligands and the complexes are given in Table 2. The
spectra of the ligands L1 and L2 show two bands in the
1520—1500 cm–1 region. These bands are assigned to
stretchingꢀbending vibrations of the triazole ring, which
are sensitive to coordination. In the IR spectra of the coorꢀ
dination compounds, one band shifts to higher frequencies
compared to that in the spectra of the ligands. This is
Table 2. Main vibrational frequencies (cm–1) in the IR spectra of the ligands and complexes 1—9
Compound
L1
ν(NH2),
ν(OH)
ν(CH)
δ(NH2)
RPh
RTrz
ν(NO3)
τ
ν(M—O)
ν(M—N)
Trz
—
3124
—
1612,
1592,
1573
1519,
1500
—
625
631
630
631
—
—
1
2
3
3316
3331
3338
3085
3084
—
—
—
1610,
1597,
1573
1529
1528
1529
1390,
1309
490,
429,
399
282
1610,
1599,
1570
1377,
1326
487,
472,
375
287,
263
3143,
3050
1610,
1596,
1571
—
486,
438,
398
276
—
L2
3359,
3321
3122,
3059
1653
1652
1599,
1566
1523,
1500
—
631
632
—
4
3400,
3334,
3206
3142,
3097
1600,
1561
1527
1527
1530
1380
467,
396,
367
283,
260
5
6
3400,
3335,
3207
3143,
3101
1651
1656
1600,
1562
1380
—
632
633
469,
398,
372
278
3340,
3304
3140,
3096
1601,
1549
459,
410,
381
271,
256
7
8
3300
3134,
3056
1641
1655
1597,
1559
1530
1530
—
635
637
463
—
3352,
3320
3096
1601,
1558
1370
455,
412,
380
278
9
3345,
3278
3190,
3104
1641
1597,
1557
1531
—
633
450,
408,
369
274

Metal(II) complexes with 1,2,4ꢀtriazoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
1935
to stretching vibrations of the NH2 group overlapping with
the stretching bands of water molecules. The spectra of
coordination compounds 4 and 5 show bands at 3400 cm–1
assigned to vibrations of outerꢀsphere water molecules.18
The spectra of all compounds have bands in the
3200—3050 cm–1 region characteristic of CH stretching
vibrations. In the spectra of the ligand L2 and coordination
compounds 4—9, the band in the 1640—1655 cm–1 region
belongs to bending vibrations of the NH2 group. This band
in the spectra of the complexes remains unchanged comꢀ
pared to that in the spectrum of the ligand, which indicates
that this group is not coordinated to the metal atom.
The lowꢀfrequency region has bands at 490—360 cm–1
assigned to ν(M—O). The bands in the 280—260 cm–1
region are attributed to ν(M—N) vibrations. Their posiꢀ
tions are characteristic of coordination compounds with
1,2,4ꢀtriazoles.19
A comparison of the number and positions of the bands
in the diffuse reflectance spectra of the CoII and NiII coorꢀ
dination compounds with the data published in the literaꢀ
ture20 shows that the coordination polyhedra in these comꢀ
pounds can be described as distorted octahedra (Table 3).
For example, the spectrum of coordination compound 2
has two bands with maxima at 20747 cm–1 (ν2) and
9671 cm–1 (ν1), which can be assigned to d—d transitions
in the octahedral ligand field, the spectrum of compound 4
shows bands at 20833 cm–1 (ν2) and 10000 cm–1 (ν1), and
the spectrum of compound 6 contains three bands at
19230 cm–1 (ν3), 15650 cm–1 (ν2), and 9346 cm–1 (ν1).
The spectra of the NiII complexes show the following
d—d transition bands: at 27700 cm–1 (ν3), 17123 cm–1
(ν2), and 10823 cm–1 (ν1) for compound 1, at 27397 cm–1
(ν3), 16892 cm–1 (ν2), and 10707 cm–1 (ν1) for compound
3, at 27397 cm–1 (ν3), 17331 cm–1 (ν2), and 10730 cm–1
(ν1) for compound 5, and at 17794 cm–1 (ν2) and
11198 cm–1 (ν1) for compound 7.
The assignment of the bands and the splitting parameꢀ
ters Δ for the CoII and NiII complexes are given in Table 3
(for the CoII coordination compounds, the parameter Δ
was calculated from the condition ν1 = 8.8 Dq).
The spectra of the copper(II) complexes have one
d—d transition band (at 16077 cm–1 for 8 and at
15748 cm–1 for 9).
The splitting parameters Δ for the CoII and NiII comꢀ
plexes corresponding to the average energy of the
d—d transitions 4T1 → 4T2 and 3A2 → 3T2, respectively, in
chromophores of the trinuclear cations of these coordinaꢀ
tion compounds are indicative of the presence of weakerꢀ
field ligands (water molecules) in the coordination polyꢀ
hedra of the terminal Co2+ and Ni2+ ions.
Complex 10 is a ionic compound. In the trinuclear
complex cation [Ni3(L1)6(H2O)4(EtOH)2]6+ (Fig. 1, a),
three nickel atoms are linked together by the bridging
ligands L1 to form a linear chain. The cation occupies an
inversion center in the space group P21/n. The coordinaꢀ
tion polyhedra of all nickel(II) ions are octahedra, the cenꢀ
tral and terminal nickel atoms being in a different coordiꢀ
nation environment (Fig. 1, b). Each pair of nickel(II) ions
is linked by three bidentateꢀbridging ligands L1 coordinatꢀ
ed through the N(1) and N(2) atoms of the triazole ring.
The coordination environment of the central nickel atom
consists of six nitrogen atoms of the ligands due to which it
is virtually undistorted. The three other coordination sites
at each terminal nickel atom are occupied by one ethanol
molecule and two water molecules. The nitrate ions are not
involved in coordination and are located in the outꢀ
er sphere.
The Cambridge Structural Database21 contains six
compounds structurally similar to the trinuclear nickel(II)
complexes with unsubstituted 1,2,4ꢀtriazole4 and with subꢀ
stituted 3,5ꢀdiaminoꢀ22 (Table 4; NADNOV, NADHAB,
and NADPAJ) and 4ꢀ(2ꢀpyridyl)ꢀ1,2,4ꢀtriazoles.7 The
Ni—N bonds with the central nickel atom in the trinuclear
coordination compounds (2.082—2.130 Å) are always
longer than the corresponding bonds with the terminal
nickel atoms (2.047—2.093 Å, see Table 4). The Ni...Ni
distances are in the range of 3.680—3.831 Å. The interꢀ
atomic distances in the structure of compound 10 vary
within the same range.
Table 3. Characteristics of the diffuse reflectance spectra of
the MII complexes with the ligands L1 and L2
Comꢀ
pound
Color
Lilac
λ
/nm
Assignment
Δ•10–3
max
/cm–1
3
1
361
584
924
482
1034
365
592
934
480
1000
365
577
932
520
639
1070
562
893
622
635
3А2 → Т1(Р)
10.8
3
3А2 → Т1(F)
3
3А2 → Т2
4
2
3
Orange
Lilac
4Т1(F) → Т1
11.0
10.7
4
4Т1 → Т2
3
3А2 → Т1(Р)
3
3А2 → Т1(F)
3
3А2 → Т2
4
4
5
Orange
Lilac
4Т1(F) → Т1
11.4
10.7
4
4Т1 → Т2
3
3А2 → Т1(Р)
3
3А2 → Т1(F)
3
3А2 → Т2
4
6
7
Pink
Lilac
4Т1(F) → Т1
10.6
11.2
4
4Т1 → А2
4
4Т1 → Т2
In the crystal structure of compound 10, each complex
cation [Ni3(L1)6(EtOH)2(H2O)4]6+ is surrounded by
a thick shell formed by solvate water and ethanol moleꢀ
cules and nitrate ions. In the crystal structure, the complex
cation is surrounded by 50 molecules and ions, only 14 of
3
3А2 → Т1(F)
3
3А2 → Т2
2
8
9
Blue
Blue
2Е → Т2
—
—
2
2Е → Т2

1936
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
a
Lider et al.
b
N(23)
C(22)
C(12)
C(21)
O(2)
N(22)
N(13)
N(21)
C(11)
N(31#1)
Ni(1)
N(11#1)
O(1)
N(12)
N(11)
N(31)
C(31)
C(1)
Ni(2)
N(32)
O(3)
N(21#1)
C(2)
C(32)
N(33)
Fig. 1. Structure of the trinuclear complex cation [Ni3(L1)6(H2O)4(EtOH)2]6+ (a); the atoms are represented by displacement ellipsoids
drawn at the 50% probability level; the hydrogen atoms are omitted. The numbering scheme for the nearest environment of the nickel
atoms (b).
these moieties being other cations. The complex cations
are linked to each other by an extensive hydrogen bond
network involving the solvate ethanol and water molecules
to form layers parallel to (101–). The O(H)...O bond
lengths are in the range of 2.635(2)—3.138(2) Å, and the
O...H—O angles vary from 125(2)° to 179(3)° (Fig. 2).
Virtually all solvate water molecules and part of nitrate
ions lie in the plane of the layer. The other nitrate ions are
located between the layers. In the crystal structure, the
layers are linked to each other by nonbonded interactions
between the phenyl substituents of the ligand L1 belonging
to the complex cations from two adjacent layers and the
solvate ethanol molecules occupying the cavities between the
phenyl rings. In spite of the fact that interactions between
the aromatic systems of the ligands of the adjacent comꢀ
plex cations can exist (intramolecular interactions cannot
occur due to the geometric features of the cation), πꢀstackꢀ
ing interactions were not found in the crystal structure of 10.
Apparently, the hydrogen bonding in the crystal structure
is energetically more favorable than stacking interactions.
In the earlier studies of the crystal structures of related
compounds,4,7,23 it has been noted that the crystal packing
is determined primarily by hydrogen bonding between the
donor and acceptor atoms of the cationic complex, the
anions, and the solvate molecules. However, the packing
of the molecules and ions in the crystal structures of comꢀ
plex 10, as well as of six known related nickel compounds,
has another distinguishing feature that persists irrespective
of the difference in the crystallographic symmetry and the
nature of the ligands. In the crystal structure of 10, the
arrangement of the sextuply charged complex cations can
be described as a distorted faceꢀcentered cubic (FCC)
packing (Fig. 3), whereas the cations in the six structurally
similar compounds form a bodyꢀcentered cubic (BCC)
lattice (see Table 4). Other structural units (solvate water
and ethanol molecules and the ClO4 and NO3 anions)
are of minor importance and fill the cavities in this crystal
packing. This conclusion is supported by variations in the
hydration number and the diverse numbers of the nearest
neighbors of the complex cations (see Table 4).
It is noteworthy that complex 10 does not have a BCC
structure characteristic of trinuclear complex cations. It
should be noted that complex 10 is the only compound
structurally studied at low temperature because crystals of
this complex undergo rapid aging in air. This suggests that
the packing of the cations depends both on the temperaꢀ
ture and the bulky substituent L1. This phenomenon will
be investigated in the future.
–
–
The Xꢀray powder diffraction study showed that
complexes
1
and
2
with the composition
[M3(L1)6(H2O)6](NO3)6•nH2O (M = Ni or Co) give
different diffraction patterns. The compound
[Ni3(L1)6(H2O)6]Cl6 (3) is Xꢀray amorphous. In the series
of the complexes with L2, coordination compounds 4—6
are crystalline. It should be noted that the Xꢀray powder
diffraction data for the first two compounds indicate that
they are isostructural. The other complexes with L2 are
Xꢀray amorphous.

Metal(II) complexes with 1,2,4ꢀtriazoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
1937

1938
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
Lider et al.
b
c
0
Fig. 2. View of the (101–) layer formed via (NO3)O...H—O(H2O) hydrogen bonds involving both the solvate water molecules and
the water molecules coordinated to the nickel atoms projected along the x axis. The trinuclear complex cations are represented
by coordination polyhedra of nickel atoms. The ligand environment, except for the water and ethanol molecules involved in hydrogen
bonding (dashed lines), are omitted.
The temperature dependences of the effective magnetꢀ
ic moment (μeff) of the NiII complexes with the ligands L1
and L2 are presented in Fig. 4. At room temperature, the
magnetic moments μeff are 4.95, 5.05, and 5.07 μB for
complexes 1, 3, and 5, respectively. These moments are
similar to the theoretical value (4.90 μB) for three virtually
noninteracting spins (s = 1, g factor = 2). The magnetic
moments μeff for the NiII complexes monotonically deꢀ
crease as the temperature decreases. At temperatures beꢀ
low 20 K, the moments approach the constant value
(~3 μB), which is similar to the pure spin magnetic moment
(2.87 μB) for s = 1. The observed magnetic behavior of the
coordination compounds is indicative of the presence of
antiferromagnetic exchange interactions between the NiII
ions, resulting in the complete spinꢀspin coupling in the
threeꢀcenter molecules at low temperatures. A further deꢀ
crease in μeff with decreasing temperature is attributed to
intermolecular antiferromagnetic exchange interactions.
The theoretical analysis of the experimental depenꢀ
dences for the NiII complexes was carried out in the clusꢀ
ter approximation with the use
of the isotropic spinꢀHamiltonian
in terms of the apꢀ
proach developed earlier.24 The apꢀ
proximation was performed with the
use of the threeꢀcenter exchange clusꢀ
ter where M = NiII. The optimal spinꢀHamiltonian paꢀ
rameters are given in Table 5. The corresponding calculatꢀ
ed curves are shown in Figs 4, a—c (solid lines).
The CuII compounds show different magnetic behavꢀ
ior. The plots μeff(T) for compounds 8 and 9 are presented
in Figs 5, a, b. The magnetic moments μeff of compounds 8
and 9 are 1.49 and 1.59 μB, respectively, already at room
temperature. These moments are smaller than the theoretꢀ
ical value (1.73 μB) for s = 1/2 with g = 2, which is associꢀ
ated with the effective antiferromagnetic exchange interꢀ

Metal(II) complexes with 1,2,4ꢀtriazoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
1939
c
b
a
Fig. 3. Fragment of the sublattice of the complex cations viewed as a FCC lattice. The nickel atoms are represented as coordination
polyhedra.
actions between CuII ions. These interactions lead to
a strong monotonic decrease in μeff as the temperature deꢀ
creases throughout the range under study. In the 50—100 K
temperature range, the plots χ(T) show a flat maximum
(the insets in Fig. 5). This magnetic behavior of comꢀ
pounds 8 and 9 characterizes their structures as exchangeꢀ
coupled linear chains. It can be seen that the magnetic
moments μeff of the CuII compounds do not turn to zero
when T → 0, which is attributed to the fact that we studied
powdered samples (the soꢀcalled effect of an "impurity
monomer"). We performed the theoretical analysis of the
temperature dependences for the CuII complexes with the
use of the chain exchange cluster taking into account the
effect of an "impurity monomer."25 The optimal exchange
parameters are given in Table 5. The theoretical curves
corresponding to these parameters are in good agreement
with the experimental curves (solid lines in Figs 5, a, b).
The exchange parameters J of the NiII and CuII comꢀ
plexes (see Table 5) are similar to those of the complexes
with triazole derivatives studied earlier.9
Hence, we synthesized trinuclear and polynuclear MII
complexes with new 1,2,4ꢀtriazole derivatives containing
a bulky substituent at position 4. It was shown that the
introduction of these substituents has no effect on the coꢀ
ordination mode of 1,2,4ꢀtriazoles but influences the comꢀ
position and magnetic properties of the compounds. The
nitrogen atoms of the substituents are not involved in coꢀ
ordination. Only the nitrogen atoms of the triazole rings
are bound to the metal atoms. The coordination environꢀ
ment of the central ions in the trinuclear CoII and NiII
complexes is formed by six N atoms of six ligands L. The
coordination units of the terminal metal ions are also octaꢀ
hedral due to coordination by three oxygen atoms of the
water molecules in complexes 1—6 (the coordination unit
Table 5. Calculated magnetochemical parameters* for the complexes with L1 and L2
Compound
Exchange
cluster
g Factor
–J
–nJ´
σ
cm–1
[Ni3(L1)6(H2O)6](NO3)6 (1)
[Ni3(L1)6(H2O)6]Cl6 (3)
[Ni3(L2)6(H2O)6](NO3)6•2H2O (5)
[Cu(L2)2(H2O)2](NO3)2 (8)
[Cu(L2)2(H2O)2]Cl2 (9)
Trimer
Trimer
Trimer
Chain
Chain
2.12 0.01
2.11 0.01
2.15 0.01
2.06
12.09 0.05
4.46 0.03
11.47 0.05
67.6
0.06 0.03
0.02 0.01
0.12 0.01
—
0.00001
0.01956
0.00063
0.0029
2.01
61.9
—
0.0013
* g is the effective g factor, J is the exchange parameter, and nJ´ is the intermolecular interaction parameter.

1940
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
μeff/μB
a
Lider et al.
μ
eff/μB
a
5.0
1.5
1.2
0.9
0.6
0.3
0
4.5
4.0
3.5
3.0
χ•103/cm3 mol–1
2.5
2.0
1.5
1.0
50 100 150 200 250 T/K
50
100
150
200
250
300
T/K
50
100
150
200
250
300 T/K
μ
1.5
1.2
0.9
0.6
0.3
0
eff/μB
b
μ
eff/μB
b
5.0
χ•103/cm3 mol–1
1.6
4.5
4.0
3.5
3.0
2.5
1.4
1.2
1.0
50 100 150 200 250 T/K
150 200 250 300 T/K
50
100
50
100
150
200
250
300 T/K
Fig. 5. Plots μeff(T) and χ(T) (inset) for the complexes
[Cu(L2)2(H2O)2](NO3)2 (8) (a) and [Cu(L2)2(H2O)2]Cl2 (9) (b).
c
μ
eff/μB
5.0
atoms of water molecules. The influence of the central
atom is manifested in that cobalt(II) and nickel(II) form
trinuclear complexes, whereas copper(II) forms polynuꢀ
clear complexes. These conclusions were drawn from the
compositions of the compounds and were confirmed by
physicochemical studies.
4.5
4.0
3.5
3.0
Experimental
The elemental analyses for C, H, and N were carried out on
a Carlo—Erba 1106 instrument in the Laboratory of Microanalyꢀ
sis of the N. N. Vorozhtsov Novosibirsk Institute of Organic
Chemistry of the Siberian Branch of the Russian Academy of
Sciences. The metal content in the complexes was analyzed by
titrating with Trilon after decomposition of the samples by heatꢀ
ing in a mixture of concentrated H2SO4 and HClO4 (1 : 2). The
number of the outerꢀsphere water molecules was determined by
thermogravimetric analysis. The TGA curves were recorded in
air on a Paulik—Paulik—Erdey derivatograph in quartz crucibles
at a heating rate of 2.5 °C min–1 with the use of Al2O3 as the
standard; the weight of the samples was 50 mg.
50
100
150
200
250
300 T/K
Fig. 4. Plots μeff(T) for the complexes [Ni3(L1)6(H2O)6](NO3)6
(1) (a), (3) (b), and
[Ni3(L1)6(H2O)6]Cl6
[Ni3(L2)6(H2O)6](NO3)6•2H2O (5) (c).
MN3O3) or one N atom of the monodentate ligand L2 and
two oxygen atoms of water molecules in complex 7
(the coordination unit MN4O2). The CuII complexes have
the CuN4O2 coordination unit formed by four nitrogen
atoms of two bidentateꢀbridging ligands and two oxygen
The singleꢀcrystal Xꢀray diffraction study of complex 10 was
performed according to a standard procedure on an automated

Metal(II) complexes with 1,2,4ꢀtriazoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
1941
Table 6. Crystallographic characteristics and the Xꢀray diffracꢀ
tion data collection and refinement statistics for complex 10
fourꢀcircle Bruker—Nonius X8Apex diffractometer equipped
with an area CCD detector at 90 K using a molybdenum anode
(λ = 0.71073 Å) and a graphite monochromator. The intensities
of reflections were measured by ϕ scanning of narrow (0.5°)
frames to 2θ = 56.7°. The empirical absorption correction was
applied using the SADABS program.26 The structure of complex
10 was solved by direct methods and refined by the fullꢀmatrix
leastꢀsquares method with anisotropic displacement parameters
for nonhydrogen atoms using the SHELXꢀ97 program package.27
The hydrogen atoms in the organic moiety were refined using
a riding model. The hydrogen atoms of the solvate water moleꢀ
cules and the hydroxy groups of the ethanol molecules were
located in difference electron density maps and refined without
restrictions. The Xꢀray diffraction data collection and refineꢀ
ment statistics are given in Table 6. Selected bond lengths and
bond angles are listed in Table 7. The molecular coordination
numbers and the topological characteristics of the cation sublatꢀ
tices were calculated using the TOPOS program package28 acꢀ
cording to a procedure described earlier.22
Parameter
Characteristic
Molecular formula
М
C68H100N30Ni3O30
1993.91
Temperature/K
Radiation (λ/Å)
Crystal system
Space group
а/Å
b/Å
c/Å
α/deg
90.0(2)
MoꢀKα (0.71073)
Monoclinic
P21/n
15.0985(4)
12.3684(3)
23.5680(6)
90
β/deg
95.1980(10)
90
4383.09(19)
2
γ/deg
V/Å3
Z
ρ
calc/g cm–3
1.511
0.735
The Xꢀray powder diffraction study was carried out on a
PhilipsꢀPW1700 diffractometer (CuꢀKα radiation, Ni filter, scinꢀ
tillation detector, the step was 0.015°, the 2θꢀangle range from
5 to 30°). The measurements were carried out at room temperaꢀ
ture using a silicon powder (a = 5.4309 Å) as the internal stanꢀ
dard. The magnetochemical measurements were performed on
a Quantum Design SQUID magnetometer in the 5—300 K temꢀ
perature range at an external magnetic field strength of 5 kOe.
The molar magnetic susceptibility (χ) was calculated taking into
account the atomic diamagnetism according to the Pascal addiꢀ
tive scheme. The effective magnetic moment was calculated by
μ/mm–1
F(000)
2084
Crystal dimensions/mm
0.291×0.273×0.062
θ/deg
hkl range
1.54—28.34
–18 ≤ h ≤ 20,
–16 ≤ k ≤ 11,
–24 ≤ l ≤ 31
Number of measured
reflections
24871
Number of independent
reflections
10866 (Rint = 0.0187)
2
the equation μeff = {[3k/(NAβ )]χT}1/2 ≈ (8χT)1/2, where k is the
Boltzmann constant, NA is Avogadro's number, and β is the Bohr
magneton. The diffuse reflectance spectra were recorded on
a Shimadzu UVꢀ3101 PC scanning spectrophotometer at room
temperature. The IR absorption spectra of the complexes were meaꢀ
sured on a Scimitar FTS 2000 spectrometer in the 375—4000 cm–1
region and on a BOMEM MBꢀ102 spectrometer in the
200—400 cm–1 region. The IR spectra of the ligands L1 and L2
were recorded on a Specord 75 IR spectrometer in KBr pellets.
The 1H NMR spectra were measured on a Bruker DPXꢀ400
instrument (400 MHz); the 13C NMR spectra, on a Bruker
DPXꢀ250 instrument (62.5 MHz, in DMSOꢀd6, HMDS as the
Number of reflections with I ≥ 2σ(I)
Method of refinement
9079
Fullꢀmatrix
leastꢀsquares based on F2
Number of refinement
parameters
GOOF
R1 (I > 2σ(I))
wR2 (based on all reflections)
627
1.039
0.0346
0.0915
Residual electron density
/e Å–3, min/max
–0.522/0.829
Table 7. Selected bond lengths (d) and bond angles (ω) in compound 10
Parameter*
Value
Parameter*
Value
Parameter*
Value
Bond
d/Å
Bond
d/Å
Angle
ω/deg
Ni(1)...Ni(2)
Ni(1)—N(11)
Ni(1)—N(21)
Ni(1)—N(31)
Ni(2)—O(1)
Ni(2)—O(2)
Ni(2)—N(12)
Ni(2)—N(22)
Ni(2)—N(32)
Ni(2)—O(3)
Ni(1)—N(11)#1
3.7869(2)
2.1420(14)
2.0983(14)
2.0962(14)
2.0533(13)
2.0685(13)
2.0644(14)
2.0468(14)
2.0558(14)
2.0659(13)
2.1420(14)
Ni(1)—N(21)#1
Ni(1)—N(31)#1
Angle
N(21)—Ni(1)—N(11)
N(31)—Ni(1)—N(11)
N(31)—Ni(1)—N(21)
N(31)#1—Ni(1)—N(21)
N(31)#1—Ni(1)—N(11)
2.0983(14)
2.0963(14)
ω/deg
88.98(5)
89.66(5)
89.35(5)
90.65(5)
90.34(5)
O(1)—Ni(2)—N(32)
O(1)—Ni(2)—O(3)
O(3)—Ni(2)—O(2)
N(12)—Ni(2)—O(3)
N(22)—Ni(2)—O(1)
N(22)—Ni(2)—O(2)
N(22)—Ni(2)—N(12)
N(22)—Ni(2)—N(32)
N(32)—Ni(2)—N(12)
N(32)—Ni(2)—O(3)
N(12)—Ni(2)—O(2)
91.97(6)
88.94(6)
93.25(5)
92.74(5)
88.37(6)
87.59(6)
89.99(6)
91.94(6)
90.00(6)
87.10(5)
92.40(6)
N(21)#1—Ni(1)—N(11)#1 88.98(5)
N(21)—Ni(1)—N(11)#1
O(1)—Ni(2)—O(2)
91.02(5)
85.62(6)
* The symmetry code (1) –x + 1, –y – 1, –z + 1.

1942
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
Lider et al.
internal standard); the 15N NMR spectrum, on a Bruker DPXꢀ
400 spectrometer (46 MHz); the chemical shifts are given with
respect to nitromethane.
Commercial reagents were used as the starting compounds
for the synthesis of the ligands L1 and L2. Acetophenone and
benzonitrile were purified by distillation (b.p. 200 and 190 °C for
acetophenone and benzonitrile, respectively). 4ꢀAminoꢀ1,2,4ꢀ
triazole was recrystallized from EtOH (m.p. 84—86 °C). The
reactants Co(NO3)2•6H2O, Ni(NO3)2•6H2O, Cu(NO3)2•3H2O,
CoCl2•6H2O, NiCl2•6H2O, and CuCl2•2H2O (highꢀpurity
grade) were used without additional purification.
HexaꢀNꢀ(1ꢀphenylethylidene)ꢀNꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)ꢀ
aminohexaaquatrinickel(II) hexachloride [Ni3(L1)6(H2O)6]Cl6 (3).
A hot solution of L1 (0.19 g, 1 mmol) in ethanol (7 mL) was
added with stirring to a solution of NiCl2•6H2O (0.12 g,
0.5 mmol) in ethanol (3 mL). The precipitate was formed after
evaporation of the excess solvent to ∼1/2 of the initial volume
and cooling of the solution. The solution with the precipitate was
allowed to age for 15 h. Then the precipitate was filtered off,
washed with hot ethanol, and dried in air. The yield of complex 3
was 0.21 g (78%).
HexaꢀN´ꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)benzamidinehexaaquatriꢀ
cobalt(II) hexanitrate dihydrate and hexaꢀN´ꢀ(4Hꢀ1,2,4ꢀtriazolꢀ
4ꢀyl)benzamidinehexaaquatrinickel(II) hexanitrate dihydrate
[M3(L2)6(H2O)6](NO3)6•2H2O (M = Co (4), Ni (5)). A hot soꢀ
lution of L2 (0.19 g, 1 mmol) in ethanol (7 mL) was added with
stirring to a solution of metal nitrate Co(NO3)2•6H2O or
Ni(NO3)2•6H2O (1 mmol, 0.29 g) in ethanol (3 mL). The comꢀ
plexes precipitated after evaporation of the excess solvent to ∼1/2
of the initial volume. The precipitates were filtered off, washed
with hot ethanol, and dried in air. The yields of complexes 4 and
5 were 0.25 g (83%) and 0.19 g (63%), respectively.
HexaꢀN´ꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)benzamidinehexaaquatriꢀ
cobalt(II) hexachloride [Co3(L2)6(H2O)6]Cl6 (6) and octaꢀN´ꢀ
(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)benzamidinetetraaquatrinickel(II) hexaꢀ
chloride [Ni3(L2)8(H2O)4]Cl6 (7). A solution of metal chloride
(0.24 g, 1 mmol) in ethanol (5 mL) was added with stirring to
a hot solution of L2 (0.57 g, 3 mmol) in ethanol (20 mL). Comꢀ
plex 6 precipitated immediately after removal of the excess solꢀ
vent. Complex 7 precipitated after evaporation of the sovent and
storage at ~20 °C for 15 h. The precipitates were filtered off,
washed with hot ethanol, and dried in air. The yields of complexꢀ
es 6 and 7 were 0.26 g (48%) and 0.34 g (52%), respectively.
DiꢀN´ꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)benzamidinediaquacopper(II)
dinitrate and diꢀN´ꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)benzamidinediaquaꢀ
copper(II) dichloride [Cu(L2)2(H2O)2]A2 (A = NO3 (8), Cl (9)).
A hot solution of L2 (0.19 g, 1 mmol for 8 or 0.38 g, 2 mmol for 9)
in ethanol (7 or 15 mL, respectively) was added with stirring to
a solution of the copper salt Cu(NO3)2•3H2O (0.24 g, 1 mmol)
or CuCl2•2H2O (0.17 g, 1 mmol) in ethanol (3 mL). The comꢀ
plexes precipitated immediately after mixing of the starting soluꢀ
tions. The precipitates were filtered off, washed with hot ethanol,
and dried in air. The yields of complexes 8 and 9 were 0.25 g
(84%) and 0.50 g (92%), respectively.
Nꢀ(1ꢀPhenylethylidene)ꢀNꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)amine (L1).
Acetophenone (100 g, 0.83 mol), EtOH (50 mL), BaO (10 g),
and 4ꢀaminoꢀ1,2,4ꢀtriazole (70 g, 0.83 mol) were mixed in
a roundꢀbottom flask. The reaction mixture was stirred at ~20 °C
for 2 days. The precipitate was filtered off and washed with chloꢀ
roform. Then the solution was collected, and the solvent was
evaporated to dryness. Ethanol was distilled off from the mother
liquor also to dryness. The dry residues were combined and
washed with water. The undissolved precipitate was filtered off
and dried. The yield was 83.5 g (54%), m.p. 155—156 °C.
Found (%): C, 64.1; H, 5.2; N, 29.7. C10H10N4. Calculated (%):
C, 64.5; H, 5.4; N, 30.1. IR, ν/cm–1: 3124, 1612, 1572, 1500,
1491, 1442, 1370, 1285, 1168, 1060, 856, 769, 692, 624,
567, 449. 1H NMR (CDCl3), δ: 8.23 (s, 2 H, HC=N, ring);
7.92 (d, 2 H, oꢀPh, J = 7.2 Hz); 7.55 (t, 1 H, рꢀPh, J = 7.0 Hz);
7.48 (t, 2 H, mꢀPh, J = 7.3 Hz); 2.39 (s, Me). 13C NMR, δ:
174 (C=N); 140.25 (HC=N, ring); 136.3 (C(1)—Ph);
132.4 (C(4)—Ph); 129 (C(2)—Ph, C(6)—Ph); 128 (C(3)—Ph,
C(5)—Ph); 17 (Me).
N´ꢀ(4Hꢀ1,2,4ꢀTriazolꢀ4ꢀyl)benzamidine (L2). Sodium hyꢀ
droxide (0.3 g, 7.5 mmol) was added to a solution containing
benzonitrile (3 g, 0.025 mol) and 4ꢀaminoꢀ1,2,4ꢀtriazole (2.79 g,
0.033 mol) in liquid ammonia (200 mL). The reaction mixture
was stirred at –33 °C for 6 h. Ammonia was removed, and the
residue was washed with water and diethyl ether. The yield was
5.2 g (96%), m.p. 245—247 °C. Found (%): C, 57.9; H, 4.7;
N, 37.4. C9H9N5. Calculated (%): C, 57.7; H, 4.9; N, 37.4. IR,
ν/cm–1: 3350, 3180, 3110, 3050, 1640, 1590, 1550, 1490, 1440,
1310, 1305, 1300, 1170, 1090, 1030, 970, 930, 920, 840, 830, 770,
700, 610, 570. 1H NMR, (CDCl3), δ: 8.46 (s, 2 H, HC=N, ring);
7.91 (d, 2 H, oꢀPh, J = 8.3 Hz); 7.53 (t, 1 H, рꢀPh, J = 8.0 Hz);
7.46 (t, 2 H, mꢀPh, J = 8.1 Hz); 7.3 (s, 2 H, NH2). 13C NMR, δ:
163.22 (C=N); 141.25 (HC=N, ring); 132.93 (C(1)—Ph); 131.65
(C(4)—Ph); 128.78 (C(2)—Ph, C(6)—Ph); 127.71 (C(3)—Ph,
C(5)—Ph). 15N NMR, δ: 64.92 (N—N); 163.75 (N(4), ring);
177.62 (N(1), N(2), ring); 294.99 (NH2).
The elemental analysis data for complexes 1—9 are given in
Table 1. The spectroscopic characteristics are listed in Tables 2
and 3.
HexaꢀNꢀ(1ꢀphenylethylidene)ꢀNꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)amiꢀ
nodiethanoltetraaquatrinickel(II) hexanitrate diethanol tetrahyꢀ
drate Ni3(L1)6(C2H5OH)2(H2O)4](NO3)6•2C2H5OH•4H2O
(10). The ligand L1 (0.0186 g, 0.1 mmol) was dissolved in ethanol
(7 mL), and the solution was added to a solution containing
nickel nitrate (0.0158 g, 0.05 mmol) in ethanol (3 mL). The
reaction solution was kept at ~20 °C. The slow crystallization
during one month afforded single crystals of the lilacꢀcolored
complex suitable for Xꢀray diffraction. According to the elemenꢀ
tal analysis and IR spectroscopic data, the polycrystalline phase
obtained in the synthesis with the use of large amounts of the
starting reagents corresponds to compound 1.
HexaꢀNꢀ(1ꢀphenylethylidene)ꢀNꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)ꢀ
aminohexaaquatrinickel(II) hexanitrate and hexaꢀNꢀ(1ꢀphenylethꢀ
ylidene)ꢀNꢀ(4Hꢀ1,2,4ꢀtriazolꢀ4ꢀyl)aminohexaaquatricobalt(II)
hexanitrate dihydrate [M3(L1)6(H2O)6](NO3)6•nH2O (M = Ni,
n = 0 (1); M = Co, n = 2 (2)). The ligand L1 (0.19 g, 1 mmol) was
dissolved in ethanol (7 mL) by heating in a water bath. The hot
solution of the ligand was added with magnetic stirring to a soluꢀ
tion of metal nitrate Ni(NO3)2•6H2O or Co(NO3)2•6H2O
(0.5 mmol, 0.15 g) in ethanol (5 mL), and the precipitates formed
immediately. The solutions with the precipitates were stirred with
gradual cooling to room temperature for 30 min. The precipitates
were filtered off, twice washed with hot ethanol, and dried in air.
The yields of complexes 1 and 2 were 0.22 g (76%) and 0.29 g
(96%), respectively.
We thank I. V. Yushina for recording diffuse reflecꢀ
tance spectra.

Metal(II) complexes with 1,2,4ꢀtriazoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
1943
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This study was financially supported by the Russian
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Received October 9, 2007;
in revised form March 20, 2008