Selective Synthesis and Complexation of Novel N,N′-Alkylene-Bridged Bis(5-pyridyltetrazole)

Article abstract of DOI:10.1002/zaac.201800242

A novel N,N′-alkylene-bridged bis(5-pyridyltetrazole) ligand, namely 2,5-bis[5-(2-pyridyl)-tetrazol-2-yl]-2,5-dimethylhexane (bpt), was prepared by regioselective N²-alkylation of 5-(2-pyridyl)tetrazole with 2,5-dimethylhexane-2,5-diol in perchloric acid. The ligand bpt was found to react with copper(II) chloride to give the dinuclear complex [Cu₂(bpt)Cl₄]. According to single-crystal X-ray analysis of the complex, bpt acts as a chelating ligand, coordinated by the metal through the tetrazole ring N⁴ and the pyridine ring nitrogen atoms. In the complex molecule, two copper atoms are linked by double chlorido bridges, and ligand bpt plays the role of the third bridge. The temperature-dependent magnetic susceptibility measurements of the complex revealed that the copper(II) ions were weakly antiferromagnetically coupled showing a coupling constant J of –1.04 cm^–1.

Full text of DOI:10.1002/zaac.201800242

Journal of Inorganic and General Chemistry
DOI: 10.1002/zaac.201800242
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
Selective Synthesis and Complexation of Novel N,NЈ-Alkylene-
Bridged Bis(5-pyridyltetrazole)
Sergei V. Voitekhovich,*[a] Anastasiya P. Mosalkova,[a] Alexander S. Lyakhov,[a] Ludmila S. Ivashkevich,[a]
Sara Schmorl,[b] Berthold Kersting,[b] and Oleg A. Ivashkevich[c]
Abstract. A novel N,NЈ-alkylene-bridged bis(5-pyridyltetrazole) li- metal through the tetrazole ring N4 and the pyridine ring nitrogen
gand, namely 2,5-bis[5-(2-pyridyl)-tetrazol-2-yl]-2,5-dimethylhexane atoms. In the complex molecule, two copper atoms are linked by
(bpt), was prepared by regioselective N2-alkylation of 5-(2-pyridyl)-
double chlorido bridges, and ligand bpt plays the role of the third
tetrazole with 2,5-dimethylhexane-2,5-diol in perchloric acid. The li- bridge. The temperature-dependent magnetic susceptibility measure-
gand bpt was found to react with copper(II) chloride to give the dinu-
clear complex [Cu2(bpt)Cl4]. According to single-crystal X-ray analy-
sis of the complex, bpt acts as a chelating ligand, coordinated by the
ments of the complex revealed that the copper(II) ions were weakly
antiferromagnetically coupled showing a coupling constant J of
–1.04 cm–1.
Introduction
Recently, high emphasis has been placed on coordination
chemistry of pyridyltetrazoles due to intriguing properties of
their metal complexes. Moreover, a wide variety of coordina-
tion modes of these multi-aza ligands allows to use them for
the design of diverse metal-organic architectures.[1] In particu-
lar, under complexation, 5-pyridyltetrazoles (Scheme 1, A) are
usually deprotonated to the tetrazolate anion, forming molecu-
lar complexes or coordination polymers, including 3D metal-
organic frameworks. Such complexes are of interest in the
areas of energetic materials,[2] chemosensors,[3] gas storage,[4]
catalysis,[5] non-linear optics,[6] light-emitting[7] and dielectric
devices.[8]
Coordination compounds of N-substituted 5-pyridyltetraz-
oles (B) have been investigated to a lesser extent,[9] and only
few metal complexes with N,NЈ-bridged bis(pyridyltetrazoles)
(C) were described till now.[10] Tetrazoles of C type are attract-
ive as multidentate ligands for the construction of polynuclear
complexes, which are interesting as the objects for magneto-
chemical studies. However, more intensive investigations in
this area are retarded by the absence of convenient methods
for the synthesis of C type ligands.
Scheme 1. 5-Pyridyltetrazoles (A), their N-substituted derivatives (B),
and N,NЈ-bridged bis(pyridyltetrazoles) (C) (X – bridging group like
alkylene, arylene et al.).
Therefore, the presented work is devoted to the elaboration
of the synthesis of N,NЈ-bridged bis(pyridyltetrazoles). Herein
we propose a facile route for the obtaining a novel N,NЈ-alkyl-
ene-bridged bis(pyridyltetrazole), and its complexation is also
investigated.
Results and Discussion
Synthesis
In general, bistetrazoles, including those of C type, can be
prepared by the alkylation of corresponding 5-monosubstituted
tetrazoles by bifunctional alkylation agents, like dihalogenal-
kanes. However, in most cases alkylation proceeds with low
regioselectivity giving mixtures of isomeric N-substituted de-
rivatives.[9a,10a] This is due to ambident character of tetrazole
ring in 5-monosubstituted tetrazoles and tetrazolates, which act
as substrates in alkylation under neutral or basic conditions. In
recent years, we are developing acid-mediated approach for
alkylation of tri- and tetrazoles.[11] This approach is based on
primary protonation of azole on the most nucleophilic endo-
cyclic nitrogen atom, which makes other one(s) accessible for
attack by carbenium cations generated from the alkylation
agents, such as alcohols or olefins. It is noteworthy that re-
gioselectivity was observed for acidic alkylation of polynu-
clear tetrazoles, which opened a facile synthetic route to poly-
* *Dr. S. V. Voitekhovich
Fax: +37-5172264696
E-Mail: azole@tut.by
[a] Research Institute for Physical Chemical Problems
Belarusian State University
Leningradskaya Street 14
220006 Minsk, Belarus
[b] Institute of Inorganic Chemistry
University of Leipzig
Johannisallee 29
04103 Leipzig, Germany
[c] Belarusian State University
Nezalezhnasti Avenue 4
220050 Minsk, Belarus
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201800242 or from the au-
thor.
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nuclear N-substituted azoles.[12,13] The latter can also be syn- 4 at 100 K are gathered in Table 2 (see Experimental Section),
thesized by alkylation of mononuclear species with polyatomic and those for 4 at 296 K are given in Table S1 (Supporting
alcohols. This route was proved using 2,5-dimethylhexane-2,5- Information).
diol (1) as alkylation agent. Thus, diol 1 was found to react
Below we discuss the crystal structures of compounds 3 and
with 5-phenyltetrazole[13] or 1,5-bis(tetrazol-5-yl)-3-oxapen- 4 only for 100 K.
tane[14] in perchloric acid giving corresponding dinuclear 2,5-
disubstituted tetrazoles, including macrocyclic one. It should
be noted that 3-amino-1,2,4-triazole and 5-aminotetrazole did
Free Ligand 3
The polycrystalline sample of free ligand 3, synthesized in
not form dinuclear azoles under action of diol 1 in analogous
conditions. In these cases N,NЈ-cycloalkylation of aminoazoles
proceeded.[15]
the presented work, contained crystals of two polymorphic
forms, namely, monoclinic and orthorhombic, denoted here as
3m and 3o, respectively.
The polymorphic form 3m crystallizes in the space group
P21/c with four ligand molecules in the unit cell. There are
two independent molecules (ligand 1 and ligand 2) in the crys-
tal structure of this form, both molecules being centrosymmet-
ric (Figure 1). The asymmetric unit of 3m comprises two half
molecules.
In order to prepare pyridyltetrazole of C type, we carried
out the reaction of 5-(2-pyridyl)tetrazole (2) and diol 1 in per-
chloric acid. As a result, only a single product, identified as
2,5-bis[5-(2-pyridyl)-tetrazol-2-yl]-2,5-dimethylhexane (bpt)
(3), was isolated (60% yield) (Scheme 2). The obtained com-
pound was attributed to 2,5-disubstituted tetrazoles based on
13C NMR chemical shifts of the tetrazole ring C5 atom, in
accordance with the data on related tetrazoles.[9b] By analogy
with tert-butylation of 2,[9b] the observed regioselectivity is
caused by the high acidity of the reaction media which leads to
the protonation on the pyridine and tetrazole N atoms. Further
alkylation of 2-(1H-tetrazol-4-ium-5-yl)pyridinium dication
proceeds on N2(N3) atoms only.
Scheme 2. Synthesis of bpt ligand.
Complexation of bistetrazole with copper(II) chloride was
carried out in ethanol-chloroform mixture and light green com-
plex [Cu2(bpt)Cl4] was isolated in 77% yield. It shows rather
high thermal stability, decomposing at a temperature above
200 °C (Figure S1, Supporting Information). Single crystals
suitable for X-ray analysis were directly picked up from the
reaction mixture. X-ray powder diffraction data of polycrystal-
line complex [Cu2(bpt)Cl4] were used to control its purity. Li-
gand 3 also formed complexes with other copper(II) salt, in
particular, bromide and tetrafluoroborate. Unfortunately, we
were not able to determine the structure of these complexes
since the samples obtained were unsuitable for X-ray analysis.
Figure 1. Two independent ligands (left – ligand 1, right – ligand 2)
in the crystal structure of 3m, with the atom-numbering scheme for
the asymmetric unit. Unlabeled atoms are related to the labeled ones
by the following symmetry operations: (a) 1–x, –y, 1–z for ligand 1,
and (b) –x, –y, 1–z for ligand 2. Displacement ellipsoids are drawn at
the 50% probability level, and the hydrogen atoms are shown as
spheres of arbitrary radii. For disordered pyridine rings, only atoms in
high-occupancy sites A are shown.
In the crystal structure of 3m, all the pyridine rings are dis-
ordered over two positions, with occupancy factor of high-
occupancy site A of 0.630(11) for ligand 1 and 0.602(11) for
Crystal Structures of Ligand bpt (3) and [Cu2(bpt)Cl4] (4)
The crystal structures of free ligand 3 and its copper(II) ligand 2. There is one non-disordered atom in the pyridine
complex 4 were obtained from single-crystal X-ray analyses. rings, namely C16 in ligand 1 and C26 in ligand 2. Peculiari-
The diffraction data were collected at a temperature of 100 K ties of the disorder, being the same in ligands 1 and 2, are
for ligand 3, and at 100 and 296 K for complex 4. As follows demonstrated in Figure 2 for ligand 1 as an example. The pyr-
from the obtained structural data, complex 4 does not undergo idine rings in sites A and B are oriented in different ways, the
phase transitions in the temperature range 100–296 K. Crystal turn of the rings relative to each other (approximately around
data, data collection, and structure refinement details for 3 and the bridge bond C–C) being close to 170°.
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Figure 2. Static disorder of the pyridine ring of ligand 1 in the crystal
structure of 3m. Solid red lines show the ring bonds in high-occupancy
site A, and dashed lines show those in site B.
As can be seen from Figure 1, the conformations of ligands
1 and 2 are practically the same. Structural similarity of the
two ligands is confirmed by the results of the molecular fit
procedure implemented in the program PLATON.[16] The pro-
cedure was applied to all non-hydrogen atoms of the molecules
with the pyridine rings in high-occupancy site A. R.m.s. devia-
tion of the atoms of fitted molecules was found to be 0.221 and
0.168 Å for weighted and unit weight functions, respectively.
Bond lengths and valence angles in ligand molecules of 3m
are usual. The angles between the least-squares planes of con-
nected pyridine and tetrazole rings are rather small, being of
1.1(2)° and 10.30(18)° in ligands 1 and 2, respectively (for the
pyridine rings in site A).
There are no hydrogen bonds in the crystal structure of 3m,
however the structure reveals weak π–π stacking interactions
Figure 3. Crystal packing of 3m, viewed along the c axis. The methyl
groups and hydrogen atoms are omitted for clarity. Dashed lines shows
between heterocycles of neighboring molecules. Among them, π–π stacking interactions.
the most strong interactions take place between the tetrazole
(Tz) and pyridine (Py) rings (all the pyridine rings are in high-
occupancy sites A). These interactions are of two types. The
interactions of the first type, formed only by ligands 1, occur
between the tetrazole ring N11/C15 at (x, y, z) and the pyridine
ring C16/C20A at (x, –½–y, –½+z), with intercentroid distance
CgTz···CgPy of 4.061(3) Å and the dihedral angle α between
the rings of 6.8(3)°. The interactions of the second type,
formed only by ligands 2, take place between the tetrazole ring
N21/C25 at (x, y, z) and the pyridine ring C26/C30A at (x,
½–y, –½+z), with CgTz···CgPy = 3.953(3) Å and α = 5.2(2)°.
The interactions of each type form corrugated polymeric layers
parallel with the bc plane. These layers are alternating along
the a axis (Figure 3).
The orthorhombic polymorphic form 3o crystallizes in the
space group Pca21, with four ligand molecules in the unit cell
and one molecule in the asymmetric unit (Figure 4).
As can be seen from Figure 4, conformation features of the
ligand in the polymorphic form 3o are very close to those in
form 3m. Comparison of the bond lengths and valence angles
in ligand molecules of both polymorphic forms shows that they
are also similar. Moreover, by using the program PLATON,[16]
the search for additional ligand symmetry in orthorhombic
form revealed closeness of the ligand structure to centrosym-
metric Ci (r.m.s. deviation of non-hydrogen atoms from centro-
symmetric positions was found to be 0.1182 Å). In pyridyl-
tetrazole fragments of orthorhombic form, the angles between
the least-squares planes of the tetrazole and pyridine rings are
Figure 4. Ligand molecule in the crystal structure of 3o, with the
atom-numbering scheme. Displacement ellipsoids are drawn at the
50% probability level and the hydrogen atoms are shown as spheres
of arbitrary radii.
It should be noted that the unit cell dimensions a, b, c of
10.03(14)° and 5.07(15)° for the fragments with the tetrazole 3m are rather close respectively to c, b, a of 3o (see Experi-
rings N11/C15 and N21/C25, respectively. These values differ mental Section, Table 2). However, the monoclinic angle β of
from those in monoclinic form only slightly.
101.5091(5)° in 3m differs from 90° significantly.
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By comparing motifs of crystal packing in the two polymor- 4 shows C2 symmetry, with the twofold axis intersecting the
phic forms, one should conclude that they are practically the middles of distances C2–C2d and Cu1···Cu1d [symmetry code
same in both forms. Despite the similarity of the two struc- (d) as in Table 1].
tures, there are hydrogen bonds in orthorhombic form, in con-
trast to the monoclinic one. These are intermolecular non-clas-
sic hydrogen bonds C20–H20···N21c between the pyridine ring
Table 1. Coordination bond lengths /Å and angles /° in the crystal
structure of complex 4.
Cu1–N4
Cu1–N5
Cu1–Cl1
Cu1–Cl1d
Cu1–Cl2
2.0480(15)
2.0448(14)
2.2607(4)
2.6154(5)
2.2253(5)
H and the tetrazole ring N atoms of neighboring molecules
[hydrogen bond arrangement: D···A = 3.465(3) Å, D–H···A =
150°; symmetry code: (c) 1–x, 2–y, z–½]. These bonds are re-
sponsible for formation of polymeric chains extending along
the c axis.
It should be noted that ligand 3o reveals π–π stacking inter-
actions being similar to those in ligand 3m. These interactions
also form corrugated polymeric layers but they are parallel
with the ab plane.
N4–Cu1–N5
N4–Cu1–Cl1
N4–Cu1–Cl1d
N4–Cu1–Cl2
N5–Cu1–Cl1
N5–Cu1–Cl2
N5–Cu1–Cl1d
Cl1–Cu1–Cl1d
Cl1–Cu1–Cl2
Cl2–Cu1–Cl1d
78.78(6)
94.37(4)
97.92(4)
146.66(5)
171.63(4)
92.51(4)
87.47(4)
88.736(15)
95.850(17)
113.932(17)
Complex [Cu2(bpt)Cl4] (4)
Complex 4 crystallizes in the monoclinic space group C2/c,
with four formula units in the unit cell. It presents a dinuclear
complex and the molecular structure is illustrated in Figure 5.
Cu1–Cl1–Cu1d
91.171(15)
3
Symmetry code: (d) 1–x, y, /2 –z.
The copper atom is pentacoordinate, being surrounded by
three chlorine atoms (Cl1, Cl1d, Cl2) and two nitrogen atoms
(the tetrazole ring N4 and the pyridine ring N5). The τ descrip-
tor[17] for penta-coordination takes on a value of 0.42, which
indicates square-pyramidal coordination of the copper atom
(extreme τ values are 0 for an ideal square pyramid and 1 for
an ideal trigonal bipyramid), the square pyramid being con-
siderably distorted. In the Cu1 square pyramid, the atoms Cl1,
Cl2 N4, and N5 occupy the basal positions, and the atom Cld
lies in the apical site. The apical bond Cu1–Cld is considerably
elongated whereas all other coordination bonds of the pyramid
are usual (Table 1). The bridges Cu–Cl–Cu are asymmetrical,
with Cu···Cu distance of 3.4919(4) Å.
In the basal plane, the angles between the opposite bonds,
viz. N5–Cu1–Cl1 and N4–Cu1–Cl2, are of 171.63(4)° and
146.66(5)°, respectively, the latter being considerably less than
180°. Among the remaining coordination angles, N5–Cu1–N4
of 78.78(6)° and Cl2–Cu1–Cl1d of 113.932(17)° differ signifi-
cantly from 90°. The former presents the coordination angle in
five-membered chelate ring.
In complex molecule of 4, Cu1 and Cu1d square pyramids
share base-to-apex edge. Mean deviation of the basal atoms
from their least-squares planes is of 0.3146(7) Å, and the two
planes are inclined at 22.59(3)°. The pyridyltetrazole fragment
of ligands is rather planar, with the dihedral angle between
the least-squares planes of the tetrazole and pyridine rings of
4.47(10)° [see also Figure 5, bottom]. The bond lengths in the
rings are as usual.
In the crystal structure of 4, there are only weak non-classic
hydrogen bonds C–H···Cl of the pyridine rings. These are in-
tramolecular hydrogen bonds C10–H10···Cl2 [hydrogen bond
arrangement: D···A = 3.2403(18) Å, D–H···A = 111°], and
Figure 5. (top) Complex molecule in the crystal structure of 4, with
the atom-numbering scheme for the asymmetric unit (displacement el-
lipsoids are drawn at the 50% probability level, and the hydrogen
atoms are shown as spheres of arbitrary radii). (bottom) Complex mol-
ecule of 4 viewed approximately along the bond Cu1–Cl1 (the
hydrogen atoms are omitted).
As can be seen, there are three bridges between the copper intermolecular hydrogen bonds C8–H8···Cl1e [hydrogen bond
atoms. Two of them are chlorido bridges, and one ligand mol- arrangement: D···A = 3.4303(19) Å, D–H···A = 129°; sym-
ecule plays the role of the third bridge. Complex molecule of metry code: (e) x+½, ½–y, z–½]. The latter is responsible for
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formation of polymeric chains running along the [–1 0 1] di-
The temperature dependence of the magnetic susceptibility
rection (Figure 6). Inside these chains, there are additional was simulated using the appropriate spin Hamiltonian [see
weak parallel π···π stacking interactions between the pyridine Equation (1)], which includes the isotropic Heisenberg-Dirac-
rings of neighboring complex molecules, with an inter-centroid Van Vleck-exchange (HDvV), as well as the single-ion Zee-
distance Cg···Cgf of 3.8747(10) Å, interplanar distance of man interactions by using a full-matrix diagonalization ap-
3.5133(7) Å, and a slippage of 1.634 Å [symmetry code: proach:
3
2
ˆ ˆ
ˆ
ˆ
ˆ
(f) /2 –x, ½–y, 1–z] (Figure 6).
H = 2(–2J1S1S2) + μB ∑i=1 (gSiB)
(1)
For complex 4, identical g-values for copper(II) ions
were assumed. As a result of best fitting, the following
parameters were obtained: g = 2.38, J = –1.04 cm–1, TIP =
5.4ϫ10–4 cm3mol–1 (TIP = temperature independent paramag-
netism).
A
number of dinuclear copper(II) complexes with
Cu(μ-Cl)2Cu core have been magnetically characterized so
far.[18,19] It has been shown that exchange coupling constant J
is determined by coordination arrangement of the copper
atoms, the bridging angles Cu–Cl–Cu, and the Cu···Cu dis-
tances. For square-pyramidal coordination of copper atoms,
magneto-structural correlations depend on the relative orienta-
tion of square pyramids. Complex 4 belongs to complexes, in
which copper(II) square pyramids share a base-to-apex edge,
and their basal planes are approximately parallel. For such
complexes, an empirical correlation has been found between J
value and the ratio φ/R (φ is the Cu–Cl–Cu bridging angle
and R is the longest Cu–Cl distance in the chloride bridge[19]).
According to this correlation, the exchange interaction is
ferromagnetic if the φ/R ratio is within the range of
31–34.5 deg·Å–1, otherwise it is antiferromagnetic. For com-
plex 4, φ/R = 34.9 deg·Å–1, as follows from the obtained struc-
tural data. Because this value is outside the above range, the
empirical correlation predicts weak antiferromagnetic ex-
change interaction for complex 4, in accordance with the
experimental value J = –1.04 cm–1.
Figure 6. Polymeric chain in the crystal structure of 4, formed by
intermolecular hydrogen bonds C8–H8···Cl1e [symmetry code: (e)
x+½, ½–y, z–½], and π···π stacking interactions between the pyridine
rings inside the chain.
Magnetic Properties of Complex 4
The presence of separated Cu2Cl4 units in complex 4 deter-
mined the interest in the magnetic investigation of the com-
pound. Figure 7 shows the μeff vs. T plot of the experimental
data and the best theoretical fit. At 330 K the curve has its
maximum and the μeff value reaches 3.03 μB. This value is
slightly above the value, expected for two non-interacting cop-
per(II) ions (S = 1/2) (μeff = 2.45 μB). With decreasing tempera-
ture the effective magnetic moment remains nearly constant to
20 K. For lower temperatures it decreases faster to a value of
2.15 μB at 2 K. Such behavior of μeff is characteristic for an
antiferromagnetic exchange between the two copper(II) ions in
the complex.
Conclusions
We have shown that 5-(2-pyridyl)tetrazole can be regiose-
lectively alkylated with 2,5-dimethylhexane-2,5-diol in per-
chloric acid generating novel multi-nitrogen ligand bpt having
two 5-(2-pyridyl)tetrazol-2-yl moieties linked by 2,5-dimeth-
ylhexane-2,5-diyl bridges. These moieties condition bis-chelat-
ing tetradentate coordination mode of bpt by means of their
N4-tetrazolyl and N-pyridyl atoms in [Cu2(bpt)Cl4] complex
formed. In this complex, two chelated copper atoms are linked
by double chlorine bridges forming Cu2Cl4 units. Magnetic
properties of [Cu2(bpt)Cl4] correspond to those expected from
magneto-structural empirical correlation.
Experimental Section
Materials and Physical Techniques: All reagents and solvents were
obtained from commercial sources and used without purification. Ele-
mental analyses for C, H, and N were performed with a FlashEA 1112
analyzer. 1H and 13C NMR spectra were recorded with a Bruker
Avance 500 spectrometer. Infrared spectra were registered with a
Nicolet Thermo Avatar 330 FT-IR system over the 400–4000 cm–1
range in SiC cavities. Thermal analysis of complex 4 was carried out
Figure 7. Temperature dependence of μeff for [Cu2(bpt)Cl4] (o) per
dinuclear unit. The solid red line represents the best theoretical fit
[Equation (1)].
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with a NETZSCH STA429 thermoanalyzer in a dynamic nitrogen at-
1241(m), 1116 (m), 1101 (w), 1044 (m), 1025 (w), 801 (m), 757 (m),
mosphere (heating rate of 10 K·min–1, aluminum oxide, mass 1–3 mg 728 (m), 645 (w), 601 (w), 426 (w) cm–1.
and temperature range from room temperature up to 500 °C).
X-ray Structure Determinations: Suitable single crystals of synthe-
sized ligand 3 and complex 4 were directly picked up from the reaction
5-(2-Pyridyl)tetrazole (2): The compound was prepared by reaction
of 2-cyanopyridine, sodium azide, and ammonium chloride in DMF
according to the published procedure.[20]
mixture. Single crystal X-ray data of both compounds were collected
with a SMART Apex II diffractometer using graphite monochromated
Mo-Kα radiation (λ = 0.71073 Å) at 100 K. Crystal data of 4 were
obtained also at 296 K. The structures were solved by direct methods
(SIR2014)[21] and refined on F2 by the full-matrix least-squares tech-
nique (SHELXL 2014).[22] The intensities were corrected for absorp-
tion. Non-hydrogen atoms were refined anisotropically. The hydrogen
atoms were placed in calculated positions and refined in a “riding”
model, with Uiso(H) = 1.5Ueq(C) for the methyl groups and Uiso(H) =
1.2Ueq(C) for the methylene and pyridine ring H atoms. Molecular
graphics was performed with the programs ORTEP-3 for Windows[23]
and PLATON.[16] X-ray powder diffraction data of polycrystalline
2,5-Bis-[5-(2-pyridyl)tetrazol-2-yl]-2,5-dimethylhexane (bpt) (3):
2,5-Dimethylhexane-2,5-diol (0.88 g, 6 mmol) was added with stirring
to 5-(2-pyridyl)tetrazole (1.77 g, 12 mmol) dissolved in 60% aqueous
perchloric acid (10 mL). The obtained solution was kept at room tem-
perature for 24 h, neutralized with aqueous ammonium hydroxide
(25%) to pH 9. The precipitate formed was filtered off and recrys-
tallized from ethanol to give bpt as colorless crystals. Yield 2.90 g
(60%). Mp 217–218 °C. C20H24N10 (404.47): C 59.70 (calcd. 59.39);
1
H 5.75 (5.98); N 34.40 (34.63)%. H NMR (500 MHz, [D6]DMSO):
δ = 1.73 (s, 12 H, 4CH3), 1.90 (s, 4 H, 2CH2), 7.52 (m, 2 H, 2CH),
7.95 (m, 2 H, 2CH), 8.05 (m, 2 H, 2CH), 8.69 (m, 2 H, 2CH) ppm.
13C NMR (126 MHz, [D6]DMSO): δ = 26.43, 35.38, 66.15. 122.16,
124.91, 137.26, 146.19, 149.86, 163.59 ppm. FT-IR (neat): ν˜ = 3066
(w), 2991 (s), 2944 (m), 1594 (s), 1575 (m), 1524 (m), 1471 (m), 1456
(s), 1431 (s), 1394 (w), 1373 (m), 1325 (s), 1292 (w), 1274 (m), 1239
(m), 1209 (w), 1156 (m), 1132 (w), 1091 (w), 1051 (s), 1040 (s), 1017
(m), 993 (m), 853 (m), 802 (s), 739 (s), 725 (m), 624 (m), 528 (w)
cm–1.
´
complex 4 were used to control its purity. The powder pattern was
recorded with an EMPYREAN diffractometer (PANalytical, Nether-
lands) using Cu-Kα radiation (Ni-filter) at room temperature (Figure
S2, Supporting Information). Crystallographic data and structure re-
finement results are summarized in Table 2.
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
numbers CCDC-1847813 (3m), CCDC-1847814 (3o), CCDC-1847815
(4, 296 K), and CCDC-1847816 (4, 100 K) (Fax: +44-1223-336-033;
E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk).
[Cu2(bpt)Cl4] (4): A solution of copper(II) chloride dihydrate (0.34 g,
0.002 mol) in ethanol (10 mL) was added to the solution of bpt (0.40 g,
0.001 mol) in an ethanol-chloroform (1:1) mixture (50 mL). The reac-
tion mixture was allowed to stand for 6 h at room temperature and
thereafter the light green crystalline complex was formed (yield 77%,
0.52 g). C20H24Br4Cu2N10 (673.38): C 35.90 (calcd. 35.67); H 3.80
(3.59); N 20.45 (20.80)%. DTG: 228 °C (dec.). FT-IR (neat): ν˜ =
Supporting Information (see footnote on the first page of this article):
Main crystal data and structure refinement details for complex 4
3093 (w), 3063 (w), 2989 (w), 2932 (w), 1615 (m), 1587 (w), 1446 (296 K); TG and DSC curves of complex 4; simulated and experimen-
(w), 1458 (s), 1445 (s), 1384 (m), 1374 (m), 1307 (m), 1268 (m),
tal PXRD patterns of complex 4.
a)
Table 2. Main crystal data and structure refinement details for two polymorphic forms of ligand 3 and complex 4.
3m
3o
4
Formula
Formula weight
T /K
C20H24N10
404.49
100(2)
C20H24N10
404.49
100(2)
C20H24Cl4Cu2N10
673.37
100(2)
Crystal system
Space group
Crystal size /mm
a /Å
b /Å
c /Å
monoclinic
P21/c
orthorhombic
Pca21
monoclinic
C2/c
0.54ϫ0.35ϫ0.11
21.2877(2)
11.09225(12)
8.79707(10)
90
0.38ϫ0.25ϫ0.11
8.80230(10)
11.1090(2)
20.8492(3)
90
0.30ϫ0.20ϫ0.10
9.15590(10)
18.5557(3)
15.5314(2)
90
α /°
β /°
γ /°
101.5091(5)
90
2035.47(4)
4
1.320
0.087
90
90
93.1513(9)
90
2634.70(6)
4
1.698
2.052
Volume /Å3
Z
2038.73(5)
4
1.318
Dc /g·cm–3
μ /mm–1
0.087
Collected reflections
Independent reflections
Rint
45845
6231
0.0284
33291
5761
0.0236
19095
3874
0.0306
Restraints
Parameters
R1 / wR2 [I Ͼ 2σ(I)]
R1 / wR2 [all data]
Goodness-of-fit
88
367
0.0415/0.1115
0.0523/0.1182
1.027
1
275
0.0432/0.1153
0.0533/0.1219
1.050
0
165
0.0274/0.0623
0.0393/0.0662
1.022
a) Z = number of formula units in unit cell; Dc = calculated density; μ = linear absorption coefficient; R1 and wR2 are discrepancy factors.
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Journal of Inorganic and General Chemistry
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
Yan, Z. Su, F. B. Dias, M. R. Bryce, Chem. Eur. J. 2017, 23,
11761–11766.
Keywords: Copper halide; Nitrogen heterocycles; Copper;
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© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Journal of Inorganic and General Chemistry
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
S. V. Voitekhovich,* A. P. Mosalkova, A. S. Lyakhov,
L. S. Ivashkevich, S. Schmorl, B. Kersting,
O. A. Ivashkevich .............................................................. 1–8
Selective Synthesis and Complexation of Novel N,NЈ-Alkyl-
ene-Bridged Bis(5-pyridyltetrazole)
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© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim