Synthesis, structural and magnetic characterization of a copper(II) complex of 2,6-di(1H-imidazol-2-yl)pyridine and its application in copper-mediated polymerization catalysis

Article abstract of DOI:10.1016/j.ica.2017.06.073

The 2,6-di(1H-imidazol-2-yl)pyridine (H₂dimpy) ligand is synthesized and suggested as an alternative ligand for copper mediated catalysis. A Cu(II) complex was obtained with this ligand and characterized via ESI-MS, FT-IR, UV–vis and the structure was confirmed by single crystal XRD. The crystal showed the [Cu₂(H₂dimpy)₂(μ-Cl)₂](PF₆)₂·2H₂O dimeric complex, in which Cu(II) is in a distorted square-pyramidal geometry (τ=0.301). Ferromagnetic coupling with J=-11.1?cm^?1 was confirmed by experiment and corroborated by density functional calculations. In order to evaluate the applicability of H₂dimpy in atom transfer radical polymerization (ATRP), polystyrene was produced in DMF solution at low polydispersity (1.3) while maintaining the livingness of the polymer chain. The good performance of the H₂dimpy compared to a standard ligand for ATRP (5,5′-dimethyl-2,2′-dipyridyl) indicates that it is suitable for this reaction.

Full text of DOI:10.1016/j.ica.2017.06.073

Accepted Manuscript
Research paper
Synthesis, structural and magnetic characterization of a copper(II) complex of
2,6-di(1H-imidazol-2-yl)pyridine and its application in copper-mediated poly-
merization catalysis
Eduardo Guimarães Ratier de Arruda, Marcelo Alexandre de Farias, Sergio
Augusto Venturinelli Jannuzzi, Stella de Almeida Gonsales, Ronaldo Adriano
Timm, Surender Sharma, Giorgio Zoppellaro, Lauro Tatsuo Kubota, Marcelo
Knobel, André Luiz Barboza Formiga
PII:
S0020-1693(17)30153-6
http://dx.doi.org/10.1016/j.ica.2017.06.073
ICA 17722
DOI:
Reference:
Inorganica Chimica Acta
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Revised Date:
Accepted Date:
2 February 2017
5 June 2017
28 June 2017
Please cite this article as: E.G. Ratier de Arruda, M.A. de Farias, S.A. Venturinelli Jannuzzi, S. de Almeida Gonsales,
R.A. Timm, S. Sharma, G. Zoppellaro, L.T. Kubota, M. Knobel, A.L. Barboza Formiga, Synthesis, structural and
magnetic characterization of a copper(II) complex of 2,6-di(1H-imidazol-2-yl)pyridine and its application in copper-
mediated polymerization catalysis, Inorganica Chimica Acta (2017), doi: http://dx.doi.org/10.1016/j.ica.
2017.06.073
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Synthesis, structural and magnetic characterization of a
copper(II) complex of 2,6-di(1H-imidazol-2-yl)pyridine
and its application in copper-mediated polymerization
catalysis
Eduardo Guimarães Ratier de Arrudaa, Marcelo Alexandre de Fariasb, Sergio
Augusto Venturinelli Jannuzzia,c, Stella de Almeida Gonsalesa, Ronaldo
Adriano Timma, Surender Sharmad, Giorgio Zoppellaroe, Lauro Tatsuo
Kubotaa, Marcelo Knobeld, André Luiz Barboza Formigaa,∗
aInstitute of Chemistry, P.O. Box 6154, University of Campinas – UNICAMP, 13083-970,
Campinas, SP, Brazil.
bBrazilian Nanotechnology National Laboratory, P.O. Box 6192, CNPEM, 13083-970,
Campinas, SP, Brazil
cDepartment of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
dInstitute of Physics Gleb Wataghin, University of Campinas – UNICAMP, 13083-859,
Campinas, SP, Brazil
eRegional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký
University Olomouc, 771 46 Olomouc, Czech Republic
Abstract
The 2,6-di(1H-imidazol-2-yl)pyridine (H2dimpy) ligand is synthesized and sug-
gested as an alternative ligand for copper mediated catalysis. A Cu(II) complex
was obtained with this ligand and characterized via ESI-MS, FT-IR, UV-Vis
and the structure was confirmed by single crystal XRD. The crystal showed
the [Cu2(H2dimpy)2(µ-Cl)2](PF6)2·2H2O dimeric complex, in which Cu(II) is
in a distorted square-pyramidal geometry (τ = 0.301). Ferromagnetic coupling
with J = −11.1 cm−1 was confirmed by experiment and corroborated by den-
sity functional calculations. In order to evaluate the applicability of H2dimpy
in atom transfer radical polymerization (ATRP), polystyrene was produced in
DMF solution at low polydispersity (1.3) while maintaining the livingness of the
polymer chain. The good performance of the H2dimpy compared to a standard
ligand for ATRP (5,5’-dimethyl-2,2’-dipyridyl) indicates that it is suitable for
∗
Corresponding author
Email address: formiga@iqm.unicamp.br (André Luiz Barboza Formiga)
Preprint submitted to Elsevier
June 5, 2017

this reaction.
Keywords: square-pyramidal copper(II), imidazol-2-yl ligand, Cu(I)-mediated
ATRP, ferromagnetic coupling
1. Introduction
Transition metal mediated atom transfer radical polymerization (ATRP)
is one of the most versatile and successful controlled radical polymerization
(CRP) methods.[1] This method provides a synthetic route for polymers and
copolymers of several architectures with well-defined composition and narrow
molecular weight distribution, while maintaining the livingness of the polymer
chain.[2, 3] ATRP catalysts based on copper as a transition metal have been
widely studied and reported in literature.[4] Usually, a suitable ligand must be a
good electron donor and facilitate a reversible one-electron Cu(I)/Cu(II) redox
process[5, 6]. The ligand should desirably offer the possibility of structural
modifications to improve solubility[7, 8], to tune in steric hindrance[9, 10] or to
allow immobilization of the catalyst[11, 12].
Previous studies revealed that substituted-terpyridines have been success-
fully used as catalysts in the ATRP[7], specially for polymerization of vinyl
acetate.[13, 14] Alternativelly, imidazol-2-yl ligands have higher basicity when
compared to pyridines[15, 16, 17], besides the possibility of this ligand to un-
dergo 1H-deprotonation [18, 19, 20] and N-derivatization.[21, 22] Yamamura
and Matyjaszewski[6] showed that the tripodal ligands bearing 2-pyridyl and 2-
imidazoyl moieties were active for Cu-mediated ATRP. Electron donation have
been increased with the number of imidazole moieties, leading to complexes
with higher formation constants and high catalytic activity.
In this perspective, we also investigate the applicability of 2,6-di(1H-imida-
zol-2-yl)pyridine (H2dimpy) as ligand for Cu(I)-mediated ATRP. This ligand
combines the denticity of terpyridine, an enhanced electron donor character
of the imidazole moieties[23] and the possibility of N-derivatization to address
solubility and immobilization demands. The synthesis of polystyrene (PS) ho-
2

mopolymers via ATRP is a well-established methodology in literature.[1, 2, 5, 6]
For this reason, we choose styrene as monomer to conduct the ATRP experi-
ments applying the H2dimpy as ligand. In order to prove the structural sim-
ilarity with terpyridine-Cu(II) complexes [24, 25], a thorough characterization
of the H2dimpy-Cu(II) complex is described.
2. Experimental Section
2.1. Materials
2,6-pyridinedicarbonitrile (97%), 2,2-diethoxyethylamine (98%), styrene (>99%),
copper(I) bromide (98%), and 1-bromoethylbenzene (97%) were purchased from
Sigma-Aldrich. Potassium hydroxide (≤85%) was purchased from Fluka Ana-
lytical. Methanol, diethyl ether (Et2O), dimethylaformamide (DMF), tetrahy-
drofuran (THF) and copper(II) chloride dihydrate (>99%) were purchased from
Vetec-Sigma (Brazil). Sodium lumps were purchased from Riedel-de Haën. All
reagents were used as received from commercial source, with no further purifi-
cation, except when noted.
2.2. Physical Measurements
Electronic spectra in the 190-1100 nm range were acquired by using a 1.00
cm quartz cuvette in a diode array HP8453 UV/Visible absorption spectropho-
tometer equipped with a HP89090A Peltier.
Electrospray ionization mass spectrometry (ESI-MS) measurements were
carried out using a Waters Quattro Micro API. Samples were evaluated in the
positive mode in an 1:1 methanol:water solution with addition of 0.10% (v/v)
formic acid.
IR spectra were measured using a Bomem MB-Series Model B100 FT-IR
spectrophotometer in the 4000–400 cm−1 range with resolution of 4 cm−1. Sam-
ples were prepared as KBr pellets.
1
13
H and C NMR spectra of the ligand were obtained in deuterated dimethyl-
1
sulfoxide solutions (DMSO-d6), for the H, using a Bruker Avance III - 400MHz
3

13
(9.4 T) spectrometer operating at 400.1824 MHz and for the C, using a Bruker
1
250 MHz (5.9 T) spectrometer operating at 62.9015 MHz. H NMR spectra of
the polymers were obtained in deuterated chloroform solutions (CDCl3) using a
Bruker Avance III - 500MHz (11.7 T) spectrometer operating at 499.8731 MHz.
EPR spectra were recorded on JEOL JES-X-320 operating at the X-band
frequency ( 9.1 GHz) at 77 K, using a liquid N2-bath cold finger. The cavity Q
quality factor was kept above 6000 in all measurements, and highly-pure quartz
tubes were employed (Suprasil, Wilmad, ≤ 0.5 OD). The EPR trace in frozen
matrix (DMSO) was simulated using the WinSimFonia programme (Version
1.25). The bulk magnetic susceptibility and magnetic susceptibility saturation
experiments were carry out on the powder sample by using the PPMS Dynacool
(Quantum Design, Inc.) in the temperature range 5-300 K, under an applied
field of 1000 Oe for the former measurement and up to 50000 Oe for the latter
measurement.
The crystallographic measurements were obtained with a Bruker Kappa
APEX II Duo diffractometer with Mo-Kα radiation (λ = 0.71073 Å). The mea-
surement was made at 100 K using the Oxford Cryostream 700 cryostat. Data
collection was made using APEX2, cell refinement and data reduction were made
using SAINT.[26] The structure was solved using SHELXLS97[27] and refined
using SHELXL2014/7[28]. ORTEP diagrams was generated using PLATON[29].
Gel permeation chromatography (GPC) measurements were performed using
a Viscotek GPCmax VE 2001, equipped with Viscotek VE 3580 RI Detector
and three Shodex KF-8060M columns working at 40 ℃. Degassed THF was
used as an eluent (1 mL min−1) and as a solvent to prepare 8.0 mg mL−1
sample solutions. The PS molecular weights were determined using polystyrene
standards.
2.3. DFT calculations
Magnetic coupling constants were calculated by the broken-symmetry U-
DFT approach, as implemented in Orca version 3.0.0.[30] The calculations were
run on top of the structure determined by X-ray diffraction using B3LYP[31, 32],
4

PBE0[33, 34, 35, 36, 37], OLYP[38] and BP86[33, 34, 39, 40, 41] functionals
with a triple zeta valence polarized basis set constructed considering relativistic
effects (def2-TZVP)[42].
2.4. Synthesis of the copper(II) complex
The synthesis of the 2,6-di(1H-imidazol-2-yl)pyridine (H2dimpy) ligand fol-
lowed standard procedures and is reported in Supporting Information.
3
A solution of CuCl2·2H2O (34.1 mg, 0.2 mmol) in 3 cm of water was added
3
to the solution of the ligand (42.1 mg, 0.2 mmol) in 3 cm of methanol. After 15
min, a saturated solution of NH4PF6 was added to promote the crystallization
of the product. The resulting deep green solution was reduced by rotatory
evaporation and upon cooling the complex precipitated as a dark green powder
which was filtered off and washed with Et2O and single crystals suitable for XRD
were obtained by slow evaporation of a H2O/MeOH solution. The compound
was obtained as a deep green solid with 52% yield (47.3 mg). Anal. calc. for
C11H9N5CuClPF6·2(H2O): C 26.90; H 2.67; N 14.26; found: C 26.65; H 2.83 and
+
N 14.38. ESI-MS (MeOH): m/z 309 and 311 [Cu(H2dimpy)Cl] , 273 and 275
[Cu(Hdimpy)] . λmax nm (L mol−1 cm−1) in MeOH: 257 (2991), 311 (3244),
+
376 (1502) and 707 (14).
2.5. Preparation of polystyrene via ATRP
The inhibitors present in the styrene monomer were removed as described
elsewhere. [43] The molar ratios monomer:initiator:CuBr:ligand used in this sec-
tion were 200:1:1:1.5. Styrene (10.0 mL, 87.3 mmol) and (1-bromoethyl)benzene
(0.060 mL, 0.436 mmol) were added to a Schlenk flask under continuous argon
flux (positive pressure). The mixture was degassed by four freeze-pump-thaw
cycles. After each thaw, the Schlenk was opened under argon flux (5 seconds),
to remove the released gases from the solution and again closed under argon
atmosphere. Then, CuBr (0.062 g, 0.436 mmol) and H2dimpy (0.125 g, 0.654
mmol) were dissolved in DMF (5 mL) and were added dropwise into the frozen
5

mixture under argon flux. The mixture was degassed by further two freeze-
pump-thaw cycles. The Schlenk flask was then immersed in a pre-heated oil
bath at 110 ℃. After 18 h, THF (20.0 mL) was added to solubilize the solid
product. The resulting mixture was permeated through a column filled with
alumina (0.15 m length), using THF as an eluent in order to remove the metal
complex catalyst from the polymeric solution. The polymeric solution was pre-
cipitated in methanol followed by drying under reduced pressure at 40 ℃ until
reaching constant mass, thus obtaining a white solid product.
Two similar experiments were performed to compare with the PS synthesized
with H2dimpy as ligand for ATRP. In the first experiment, the PS polymeriza-
tion was conducted following the same procedure described above but with-
out solvent (i.e. DMF). The second experiment was conducted as described
elsewhere[43]. Briefly, the styrene polymerization was performed using 5,5’-
dimethyl-2,2’-dipyridyl as ligand instead of using H2dimpy. The choice for a
substituted dipyridyl ligand for comparison was based on the solubility of the
ligand in the conditions of the experiment.
3. Results and Discussion
3.1. Characterization of the H2dimpy and the copper(II) complex
The H2dimpy ligand was synthesized using the procedure described by Voss
1
13
and co-workers[44]. The product was characterized using H, C NMR and ESI-
MS techniques and the spectra shown in Figures S1–S3 respectively were consis-
tent with literature data [45, 44, 18]. The synthesis procedure was straightfor-
ward and is a high-yielding methodology to obtain the pure ligand. Interestingly,
1
the H NMR spectrum showed unprecedented non-equivalence of the imidazole
moieties in dry DMSO-d6. The reader is referred to the Supporting Information
for further details and discussion on spectroscopic and spectrometric character-
izations of both compounds.
The copper(II) complex has been synthesized adapting the method described
by Stupka and co-workers[18] for H2dimpy complexes of others transition met-
6

als. The synthesis was made mixing 1:1 of H2dimpy:CuCl2 stoichiometry in
H2O/MeOH mixture, as depicted in the reaction scheme of Figure S4. The
product obtained was very soluble in water, soluble in polar solvents (methanol,
DMSO, DMF), slightly soluble in acetonitrile and ethanol and insoluble in di-
ethylether and n-hexane. Figures S5 and S6 present ESI-MS spectra of the
complex. Figure S7 exhibit the FT-IR spectra of both H2dimpy and the com-
plex, whose comparison corroborates the structural features revealed by single
crystal XRD discussed below.
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Figure 1: UV-Vis spectra of the H2dimpy in MeOH and the copper(II) complex in H2O.
The UV-Vis spectra of both H2dimpy ligand and complex are shown in Fig-
ure 1. The spectrum of the ligand (depicted in solid line) shows three intense
bands at 206, 277, 318 nm assigned to π → π∗ bands.[18, 19] Upon coordination
to Cu(II), all three bands were shifted to higher wavelengths. At higher concen-
tration, the spectrum of the complex also revealed a very weak and broad band
at 680 nm that can be assigned to a d → d band, both in solution and in solid
state, as shown in Figure S8. In comparison with the d → d band of copper(II)
chloride dissolved in water (814 nm, see Figure S9) this band is blueshifted,
which is consistent with an increase in ligand field after coordination through
the imine moiety.
The energy of the d − d band is consistent with pentacoordinated Cu(II) in
7

a square-pyramidal structure,[46] suggesting presence of the solvent molecule
as the fifth ligand or maintenance of the dimer observed in the solid state (see
Figure 2) in analogy with other examples with chloride and N-donor ligands.[47,
48, 25, 24] During the experiment, no change was observed in the spectrum
while changing the concentration of the solution (5×10−2 to 5×10−5 mol L−1
)
suggesting the maintenance of the structure while dissolving the complex in
H2O.
3.2. Crystal structure of the copper(II) complex
The refinement of diffraction data revealed a dimeric structure with two
chloride bridges with an overall formula of [Cu2(H2dimpy)2(Cl)2](PF6)2·2H2O.
Table 1 presents the crystallographic information. The dimeric structure has ap-
proximate C2h point group with the inversion center positioned in the barycenter
of the rhomboidal Cu2(µ-Cl)2 core, resulting in observation of one unique atom
of each type (Figure 2). Only one imidazole ring, per ligand, is involved in
hydrogen bonding with the unique water molecule in the crystal. The distance
N5–O1 is 2.821(3) Å and the angle N5–H5–O1 is ca. 161.9°. The presence of two
PF−6 counter-ions confirms that the ligand is not deprotonated in the complex.
Some selected bond distances and angles used for structural discussion are
shown in Table 2. The rhomboid structure of the Cu2(µ-Cl)2 core was observed,
where the copper is the obtuse vertex (93.61°) and the chloride the acute vertex
(86.39°), with the Cu1–Cu1a distance equal to 3.4812 Å and the distance Cl1–
Cl1a equal to 3.702 Å. The copper atom is in a distorted square-pyramidal
geometry (τ= 0.301, using α = 158.43° and β = 176.48°)[49]. The dimer can
be classified as parallel showing a 0.562 Å difference between the Cu-Clapical
and the Cu-Clbasal bond distances, which is consistent with literature data for
copper(II) complexes with the Cu2(µ-Cl)2 core.[48, 25, 24, 50, 47]
The structure is different from one obtained for the analogous complex with
2,6-bis(benzimidazol-2-yl)pyridine[51], which is neutral with two chloride lig-
ands per Cu(II). It has the same coordination geometry, but no Cl bridges
probably due to the lack of PF−6 anions.
8

Table
1:
Structural
data
from
the
single-crystal
XRD
of
the
[Cu2(H2dimpy)2(Cl)2](PF6)2·2H2O complex.
Molecular formula
[Cu2(C11H9N5)2Cl2](PF6)2·2H2O
Formula weight (g mol−1
λ (Mo Kα, Å)
Space group
Crystal System
a (Å)
)
946.44
0.71073
P21/c
Monoclinic
12.744(3)
6.873(1)
b (Å)
c (Å)
18.606(4)
102.255(4)
1592.5(5)
2
β(°)
3
V (Å )
Z
T (K)
100
ρcalc (g cm−3
)
1.974
F(000)
940
Reflections collected/unique
Data/restraints/parameters
R1,wR2 [I > 2σ (I)]
24562/3385 [Rint = 0.051]
3385/2/247
0.030, 0.065
0.51, −0.37
1.04
3
Diff. peak and hole (e/Å )
2
Goodness of fit in F
9

Figure 2: ORTEP image of the complex [Cu2(H2dimpy)2(µ-Cl)2](PF6)2·2H2O with ellipsoids
corresponds to 50% probability. Only the unique water molecule and hexafluorophosphate ion
are shown for clarity (see discussion).
Table 2: Selected bond distances and angles from the single-crystal XRD of the complex.
Bond distance (Å)
Cu1–Cl1 2.2445(8) Cu1–Cl1–Cu1a 86.39(2)
Cu1a–Cl1 2.8061(8) Cl1–Cu1–Cl1a 93.61(2)
Angle (°)
Cu1–N1
Cu1–N3
Cu1–N5
1.977(2)
2.001(2)
1.989(2)
N3–Cu1–N5
N4–Cu1–Cl1
N3–Cu1–Cl1
158.47(8)
176.49(6)
100.77(6)
90.59(6)
Cu1–Cu1a 3.4812(8) N5–Cu1–Cl1a
Cl1–Cl1a
N1–Cl1
3.702(1)
4.220(2)
1.96(3)
N3–C1–C5–N5 0.7(2)
N3–C6–C5–N1 –1.3(3)
O8–H26
The shortest Cu(II)–N distance is found for pyridinic N1, which is 0.024 Å
shorter than for imidazole N3 and 0.012 Å shorter for the other imidazole
N5. This is consistent with the rigidity of the tridentate ligand resulting in
a relatively wide N1–Cu1–N5 angle (158.47°) for the trans imidazoles. The
Cu(II)–N and Cu(II)–Cl distances are very close to those found in similar
10

complexes.[45, 52, 53, 54] The three rings in H2dimpy are almost coplanar with
torsion angles N3–C1–C5–N5 and N3–C6–C5–N1 near 0°. Moreover, Cl1 in the
base of the pyramid is trans to pyridine with a nearly linear angle (176.48°)
which confirms that Cu(II) is sitting in the base of the pyramid.
Comparing the Cu(II) complex structure with the one obtained for others
first and second-row metal complexes of H2dimpy, the distance between the M–
Nimidazole is typically shorter than M–Npyridine, for Mn(II), Fe(II), Co(III) and
Ru(II).[18, 55, 56] The octahedral coordination of the metal by two H2dimpy
ligands is favored for most of other metals, while for Cu(II) the synthesis with
ligand excess (2:1 ligand:metal) resulted in the same product. To the best of
our knowledge, the only other example of pentacoordinated H2dimpy complex
is with Fe(II) in a Fe2S2 cluster.
3.3. Magnetic characterization of the copper(II) complex
The X-band (9.1 GHz) EPR spectra of the complex were studied in both
powder form and in frozen DMSO solution at 77 K. The results are presented
in Figure 3a and 3b, respectively.
The EPR resonance line of the complex as neat powder saturated very fast,
and only low-microwave energy was employed in order to prevent line-width
broadening and strong signal distortion. The powder spectrum recorded at
0.05 mW (Figure 3a) exhibited a resolved signature typically encountered for
axial Cu(II) cations, with gk of 2.214, g⊥ of 2.064 and hence gavg value of
2.11. The experimentally determined g-values are consistent with the structural
organization of the complex as seen from X-ray analysis, in which both Cu(II)
cations adopt a square pyramidal fashion and are embedded in a ligand field
containing three nitrogens donors supplied by the H2dimpy ligands.
2
2
From the resonance profile, the unpaired electrons populate the dx −y or-
bital. The half-field transition (∆Ms=2) is shown as inset in Figure 3a and it
was observed even at such low microwave power, and is found here 100 times
weaker than the ∆Ms=1 resonance line. Such feature clearly indicates the pres-
ence of triplet species being active in the system. The emergence of the ∆Ms=2
11

Figure 3: (a) EPR spectrum of [Cu2(H2dimpy)2(µ-Cl)2](PF6)2·2H2O complex in powder
form recorded at 77 K. Experimental parameters: 9.154 GHz microwave frequency, modu-
lation frequency of 100 kHz, 0.05 mW microwave power, 1 mT modulation width, 0.03 s
time constant. The inset shows the appearance of the half-field transition observed under
the same conditions. (b) EPR spectrum of the complex in frozen matrix solution (77 K in
DMSO, upper trace, Obs) together with its spectrum simulation (lower trace, Sim). Exper-
imental parameters: 9.142 GHz microwave frequency, modulation frequency of 100 kHz, 0.3
mW microwave power, 0.7 mT modulation width, 0.03 s time constant. (c) The product χM T
versus T (open circles) of bulk powder complex together with the fitting analysis (solid line)
in term of Bleaney-Bowers (S = 1/2 coupled dimers). The inset shows the saturation of the
magnetization M recorded at 5 K. The solid line and shows the fitting using the Brillouin
function (S = 1) and the broken line is a guide to the eyes that highlights the region with
linear response between M vs H.
12

transition agrees with the fact that in the complex exists a relative short Cu1-
Cu1a distance of 3.4811 Å that renders the magnetic interaction between the
two spin-active centers possible not only through-space but also via the super-
exchange pathway provided by the two chloride bridges.
The frozen DMSO solution spectrum obtained at 77 K with concentration of
1×10−4 mol L−1 is shown in Figure 3b (upper trace) together with its computer
simulation (lower trace). The EPR envelope of the complex becomes better
resolved in frozen solution than in the powder form, in which dipolar through-
space interactions generate resonance spread and severe line broadening, and
appears more consistent with the resonance expected for weakly coupled Cu(II)-
complexes. [57, 58, 59]
The spectrum shows a well resolved hyperfine splitting arising from the in-
teraction of the unpaired electron with the I = 3/2 Cu(II) nuclear spin. The
following spin Hamiltonian parameters were derived from computer simulation
in the spin Hamiltonian approximation: gk of 2.236, g⊥ of 2.045 (gavg of 2.11)
and Ak of 16.2 mT with line-width tensor (Lx,y,z) of 9 mT, 9 mT, 5 mT and
Lorentzian/Gaussian ratio of 1.00. In frozen solution, no half-field transition
could be observed, even upon increasing the microwave energy up to 10 mW.
The magnetic behavior of the complex was additionally studied by bulk
susceptibility measurements (PPMS) in the temperature range 5–300 K. In order
to confirm that the crystalline structure did not change with temperature we
have determined unit cell parameters at 296 K and observed the expansion
of the cell (Table S1) at higher temperature. The experimentally determined
bulk magnetic properties of the copper complex under an applied field of 1 kOe
are shown in Figure 3c. At 300 K the product χM T corrected by considering
the diamagnetic term (χDI) of –5.19×10−4 emu mol−1 as derived from Pascal
3
Tables, is 0.85 K cm mol−1. The experimental χM T value is found larger than
that expected for two interacting S = 1/2 spin-system in thermal equilibrium
according to the Boltzmann distribution between triplet and singlet states, with
3
χM T = 0.75 K cm mol−1 for gavg of 2.00.
Upon lowering the temperature, the χM T product increases slowly and then
13

3
sharply below 50 K, reaching the value of 1.08 K cm mol−1 at 5 K. The overall
trend of the magnetic moment clearly indicates that the dominant magnetic
interaction of bulk complex is ferromagnetic. The system has been analyzed by
the Bleaney-Bowers equation, in term of spin-coupled dimer, using the following
convention for the spin Hamiltonian H = JSASB1. The best fitting results are
obtained by using the experimentally determined gavg of 2.11, and gives an
intermediate size for the ferromagnetic interaction J of –11.1 cm−1. Inclusion
in the fitting of intermolecular interactions (zJI) did not provide better results,
and hence intermolecular interactions among dimers must be rather weak.
The field dependence magnetization recorded at 5 K is given as inset in
Figure 3c. The data provides further evidences of the S = 1 magnetic ground
state, upon fitting the M /N µB vs H (Oe) plot with the Brillouin equation. The
fitting analysis gives a Landé gavg-factor of 2.09, similar to that experimentally
determined, gavg of 2.11.
It should be noticed that Marsh and co-workers, and more recently revisited
2+
in other works, have proposed for [Cu2(µ-Cl)2] systems an empirical correla-
tion between J and the a/R ratio, where a represents the Cu-Cl-Cu angle and R
the longest Cu-Cl distance.[60, 61, 62, 63] They noted that when the a/R values
are lower than 32.6 or larger than 35.8° Å−1, the expected magnetic interaction
should be antiferromagnetic, while values falling within these limits gives a fer-
romagnetic interaction between the Cu centers. Our system does not follow the
expected trend. Since in [Cu2(H2dimpy)2(µ-Cl)2](PF6)2 the a/R value is equal
to 30.79°Å−1 (86.39°/2.8061 Å) an antiferromagnetic interaction is anticipated,
which is not observed here experimentally.
Similar results that fall outside the correlation proposed by Marsh and co-
workers have been obtained by Lumb and co-authors on the N,N-diisoprop-
ylpicolinamide Cu(II) binuclear complex that contains a similar the (µ-Cl)2
bridge.[64] In their case, the a/R value of 38.7°Å−1 obtained from X-ray corre-
lated with an experimentally derived strong ferromagnetic intradimer coupling
1This convention is kept throughout this discussion.
14

constant (J = −43.1 cm−1). Moreover, Sikdar and co-authors also observed
that in their [Cu2(µ-Cl)2L2]Cl2 complex where L is the Schiff base 5-[(pyridin-
2-ylmethylene)-amino]-pentan-1-ol the magnetic interaction is weakly antiferro-
magnetic (J = 0.47 cm−1) with a/R value of 32.77°Å−1, which does not fit as
well the trend expected from the Marsh relation.[59]
It is noteworthy comparing the H2dimpy complex with LCu(µ-Cl)2CuL
dimers with L being terpyridine and tridentate ligands bearing pyridine and
2+
imidazole. The geometry of the Cu2(µ-Cl)2 rhomboid of [Cu2(terpy)2(µ-Cl)2]
2+
2
[24], [Cu2(apyhist)2(µ-Cl)2] [62] and [Cu2(pypep)2(µ-Cl)2][65] are similar to
the H2dimpy complex and yet they have antiferromagnetic coupling. On the
other hand, the tris(1-methylbenzotriazole) copper(II) chloride dimer presents
ferromagnetic coupling, also in disagreement with expected by a/R.[63]
In order to investigate in more detail the exchange interaction between the
metal centers we performed broken-symmetry DFT calculations with the struc-
ture obtained by XRD and with different functionals. Calculations considered
only the dimeric structure, neglecting water and PF−6 . Magnetic coupling anal-
ysis resulted in data presented in Table S2 and the J values are given in Table
3, calculated by Eq. 1[66]. The spin contamination in hybrid and pure GGA
functionals was low. The maximum difference hS2i − S(S + 1) was 0.006 for
PBE0. Despite the lack of quantitative agreement with the experimental value
of 11.1 cm−1, the calculated values of J for all functionals agrees with ferro-
magnetic coupling.
EHS − EBS
hS2iHS − hS2iBS
J = −
(1)
The singly occupied Kohn-Sham orbitals are antibonding combinations of
2
2
Cu(3dx −y ) and σ orbitals of H2dimpy and Cl, which are evident from the spin
density plot of the broken symmetry singlet shown in Figure 4 Moreover, the
2
2
unpaired electron located in an orbital with significant Cu(3dx −y ) character
corroborates the interpretation of the EPR resonance profile discussed above.
2apyhist is (4-imidazolyl)ethylene-2-amino-1-ethylpyridine and pypep is N-(2-(4-
imidazolyl)ethyl)-pyridine-2-carboxamide.
15

−1
Table 3: Magnetic coupling constants (J) in units of cm
calculated by Eq. 1 and Mulliken
spin population (ρ) of the triplet state provided by single point DFT calculations on top of
the structure obtained by XRD for the [Cu2(H2dimpy)2Cl2]2+ complex shown in Figure 2.
Functional
J
PBE0 B3LYP OLYP BP86
–0.79
0.63
0.11
0.10
0.08
–1.13
0.60
0.12
0.10
0.09
–1.13 –3.84
ρ(Cu1)
ρ(Cl1)
0.60
0.12
0.10
0.09
0.50
0.16
0.12
0.10
ρ(N1)
ρ(N3),ρ(N5)
The spin population listed in Table 3 indicate that the unpaired electrons are
mainly located over the metal atoms, and also over the binding atoms. It is also
noticeable spin density spread over both chloride bridges, supporting that the
mechanism for exchange interaction may occur through them.
Figure 4: Spin density of the broken-symmetry singlet state calculated by B3LYP/def2-TZVP
using the experimental geometry of the dimeric [Cu2(H2dimpy)2(Cl)2]2+. Isovalue is 0.0015
−3
e a.u.
.
3.4. Polystyrene synthesis
The synthesis of polystyrene (PS) homopolymers via ATRP is a well-establ-
ished methodology in the literature, hence it was used as a standard reaction to
evaluate the performance of H2dimpy as a ligand for ATRP. Catalysts based on
copper have been widely reported and showed the importance of the presence of
16

Figure 5: GPC curves of PS-s and PS-b homopolymers synthesized via ATRP.
Table 4: Molecular parameters obtained for the PS homopolymers.
a
b
c
d
Polymer Mn (g mol−1
)
MNMR (g mol−1
)
Mn,theo (g mol−1
)
Ð
PS-b
PS-s
2,100
16,300
17,600
6,800
20,400
17,700
20,800
20,800
20,800
1.7
1.3
1.2
PS-m
a
b
Determined by GPC with THF as the eluent with respect to polystyrene standards. Ob-
tained using the signal intensity ratios between the 7.37–6.21 ppm and those in the 4.60–4.35
c
ppm range. Considering complete conversion with the monomer/initiator/CuBr ratio used.
d
Ð = Mw/Mn
ligands to stabilize the intermediates and increase the kinetic rates.[67, 68, 69, 7]
The synthesis of PS via ATRP using H2dimpy as ligand were conducted
in bulk and solution to yield the samples labeled as PS-b and PS-s respec-
tively. The gel permeation chromatograms of PS-b and PS-s (Figure 5) show
monomodal and multimodal GPC curves for PS-s and PS-b, respectively. The
number average molecular weight (Mn) and polydispersity index Ð(= Mw/Mn)
values of PS-b and PS-s are presented in Table 4.
One of the criteria used in the literature to define a controlled polymerization
is based on the Ð values, in which Ð ≤ 1.5 is considered a narrow molecular
weight distribution[67, 70, 4, 71], whereas Ð ≤ 1.2 is indicative of very narrow
polydispersity. The latter is usually obtained at low monomer conversion rates
17

and/or by using solvent in the polymerization.[72, 73, 74] The low solubility of
H2dimpy and Cu(I) halide in liquid styrene resulted in poor controlled reaction
(i.e. Ð = 1.7) and low monomer conversion (Mn = 2,100 g mol−1) under bulk
condition. On the other hand, the PS synthesis in solution led to a narrow
molecular weight distribution (i.e Ð = 1.3) and high monomer conversion (Mn
= 16,300 g mol−1), indicating that the synthesis of PS via ATRP using H2dimpy
as ligand should not be conducted in bulk conditions.
Figure 6: 1H NMR spectrum of the PS-s with inset showing the 4.60-4.35 ppm range magni-
fication obtained in the 500 MHz spectrometer.
1
Figure 6 shows the H NMR spectrum of PS-s synthesized via ATRP. The
signals at 4.60-4.35 ppm were attributed to the hydrogen located in the α posi-
tion of the bromine chain end (hydrogen “a”), confirming the preservation of the
bromide chain end group in the PS homopolymers. The retention of chain-end
functionality is one important aspect of the CRP techniques.[75] Based on the
signal intensity ratios between the 7.37–6.21 ppm range and those in the 4.60–
1
4.35 ppm range, the calculated molecular weight by H NMR (MNMR) of PS-s,
considering the ratio monomer:chain end, was ca. 20,400 g mol−1, indicating
that the homopolymer synthesized is made up of 196 styrene units per bromide
chain end on average.
Another PS sample (labeled as PS-m) was synthesized but now using 5,5’-
dimethyl-2,2’-dipyridyl in order to benchmark the H2dimpy performance against
a known ligand for Cu(I)-mediated ATRP. Comparing the data on Table 4 for
PS-m with the PS-s, one can note that PS-m presented very narrow polydis-
18

persity (Ð = 1.2) and similar Mn values (Mn = 17,600 g mol−1) relative to the
PS-s sample.[43] The difference in Ð values between PS-m and PS-s may be
attributed to the solubility of the Cu(II) intermediate formed using H2dimpy
or 5,5’-dimethyl-2,2’-dipyridyl, since solubility is a limiting factor for a better
controlled reaction with lower polydispersity.
In spite of that, the similar values of Ð and Mn presented by both PS-
m and PS-s samples indicate that H2dimpy can be used as ligand for ATRP.
Furthermore, the characteristics of the polymerization carried out by H2dimpy
in solution is in agreement with the described for the alkyl-substituted ter-
pyridines, whose polydispersity is lower than 1.3[7]. The advantage of H2dimpy
is that it can be easily alkyl-substituted when compared with terpyridines.
The amine moiety of the imidazole allows addition of a hydrophobic alkyl
group via straightforward nucleophilic substitution with the corresponding alkyl
halide[76, 77, 78, 79].
4. Conclusions
The structure of a dimeric complex between H2dimpy and Cu(II) was con-
firmed using both spectroscopic and single crystal XRD. Cu(II) is in a distorted
square-pyramidal geometry and the magnetic behavior of the complex is consis-
tent with weak ferro magnetically spin-coupled copper centers, with estimated
exchange constant (J) of –11.1 cm−1, as obtained from magnetic susceptibility
studies. The interaction between the metals centers was modeled using broken-
symmetry DFT calculations. The values for J given by four functionals indicated
a ferromagnetic coupling, in agreement with the experimental results. The cal-
culations showed that the singly occupied Kohn-Sham orbital is an antibonding
combination of Cu(II) 3dx −y and σ orbitals of H2dimpy and Cl−, as expected
from the experimental EPR resonance profile. The spin density plot showed
a density spread over the metal and ligand atoms, in special over the chloride
bridges, suggesting that the mechanism for the exchange interaction may be
through them. The H2dimpy was successfully applied as ligand to synthesize
2
2
19

polystyrene via ATRP using DMF as a solvent, highlighting its applicability
in Cu(I)-mediated catalysis. The polystyrene presented controlled molecular
weight and relatively narrow polydispersity similar to the result obtained with
terpyridine derivatives and classic ligands, as 5,5’-dimethyl-2,2’-dipyridyl.
Acknowledgements
This work was supported by the Conselho Nacional de Desenvolvimento
Científico e Tecnológico (CNPq) [grant numbers 402627/2012-1, 202911/2014-4
and 131848/2013-5]; the Fundação de Amparo à Pesquisa do Estado de São
Paulo (FAPESP) [grant numbers 2012/12773-1 and 2013/22127-2]; the Insti-
tuto Nacional de C,T & I em Materiais Complexos Funcionais (INOMAT); the
Nanomaterials and Nanotechnologies for Environment Protection and Sustain-
able Future (NanoEnviCz) [grant number LM2015073]; the Centro Nacional de
Processamento de Alto Desempenho em São Paulo (CENAPAD-SP).
Authors would like to thank Prof. Dr. Maria do Carmo Gonçalves for ideas
and discussion, MSc. Paula Aragão Lima and Carolina Galluppo for NMR and
ESI-MS sample preparation, and Dr. Déborah de Alencar Simoni for the support
with the XRD analysis.
Supplementary material
Supplementary crystallographic data is available for this paper. These data
can be obtained free of charge from The Cambridge Crystallographic Data Cen-
ter via www.ccdc.cam.ac.uk/data_request/cif via CCDC number 1036684.
Nuclear magnetic resonance, mass spectrometry, electronic and infrared spec-
tra are available as supplementary material. Room temperature crystallographic
data (cell parameters) and DFT results can also be obtained as supplementary
material.
20

References
[1] Y. Wang, Y. Kwak, K. Matyjaszewski, Macromolecules 45 (2012) 5911–
5915.
[2] K. Matyjaszewski, in: M. O. Masakazu Anpo, H. Yamashita (Eds.), Science
and Technology in Catalysis, Vol. 145, Elsevier, 2003, pp. 3–11.
[3] N. Ayres, Polym. Rev. 51 (2011) 138–162.
[4] K. Matyjaszewski, J. Xia, Chem. Rev. 101 (2001) 2921–2990.
[5] K. Matyjaszewski, Chem. Eur. J. 5 (1999) 3095–3102.
[6] Y. Yamamura, K. Matyjaszewski, J. Polym. Sci., Part A: Polym. Chem. 46
(2008) 2015–2024.
[7] G. Kickelbick, K. Matyjaszewski, Macromol. Rapid Commun. 20 (1999)
341–346.
[8] M. H. Acar, N. Bicak, J. Polym. Sci. A Polym. Chem. 41 (2003) 1677–1680.
[9] Y. Inoue, K. Matyjaszewski, Macromolecules 37 (2004) 4014–4021.
[10] W. Tang, Y. Kwak, W. Braunecker, N. V. Tsarevsky, M. L. Coote, K. Maty-
jaszewski, J. Am. Chem. Soc. 130 (2008) 10702–10713.
[11] J. V. Nguyen, C. W. Jones, Macromolecules 37 (2004) 1190–1203.
[12] M. Kamigaito, T. Ando, M. Sawamoto, Chem. Rev. 101 (2001) 3689–3746.
[13] H. Tang, M. Radosz, Y. Shen, in: ACS Symposium Series, Vol. 1023, Amer-
ican Chemical Society, 2009, pp. 139–157.
[14] H. Tang, M. Radosz, Y. Shen, AIChE J. 55 (2009) 737–746.
[15] H. E. Toma, J. A. Vanin, J. M. Malin, Inorg. Chim. Acta 33 (1979) L157–
L159.
21

[16] M. O. Santiago, C. L. Filho, I. d. S. Moreira, R. M. Carlos, S. L. Queiroz,
A. A. Batista, Polyhedron 22 (2003) 3205–3211.
[17] J. Bezençon, M. B. Wittwer, B. Cutting, M. Smieško, B. Wagner, M. Kansy,
B. Ernst, J. Pharm. Biomed. Anal. 93 (2014) 147–155.
[18] G. Stupka, L. Gremaud, G. Bernardinelli, A. F. Williams, Dalton Trans.
(2004) 407–412.
[19] G. Stupka, L. Gremaud, A. F. Williams, Helv. Chim. Acta 88 (2005) 487–
495.
[20] M. M. Konnick, S. M. Bischof, R. A. Periana, B. G. Hashiguchi, Adv.
Synth. Catal. 355 (2013) 632–636.
[21] M.-a. Haga, H.-G. Hong, Y. Shiozawa, Y. Kawata, H. Monjushiro,
T. Fukuo, R. Arakawa, Inorg. Chem. 39 (2000) 4566–4573.
[22] Y. H. Lee, A. Ohta, Y. Yamamoto, Y. Komatsu, K. Kato, T. Shimizu,
H. Shinoda, S. Hayami, Polyhedron 30 (2011) 3001–3005.
[23] M. L. Rigsby, S. Mandal, W. Nam, L. C. Spencer, A. Llobet, S. S. Stahl,
Chem. Sci. 3 (2012) 3058–3062.
[24] T. Rojo, M. I. Arriortua, J. Ruiz, J. Darriet, G. Villeneuve, D. Beltran-
Porter, J. Chem. Soc., Dalton Trans. (1987) 285–291.
[25] T. Rojo, J. Darriet, J. Dance, D. Beltrán-Porter, Inorg. Chim. Acta 64
(1982) L105–L107.
[26] Bruker, Tech. rep., Bruker, Bruker AXS Inc., Madison, Wisconsin, USA.
(2010).
[27] G. M. Sheldrick, Acta Crystallogr. Sect. A 64 (2008) 112–122.
[28] G. M. Sheldrick, Acta Crystallogr. Sect. C-Cryst. Struct. Commun. 71
(2015) 3–8.
22

[29] A. L. Spek, J. Appl. Crystallogr. 36 (2003) 7–13.
[30] F. Neese, WIREs Comput. Mol. Sci. 2 (2012) 73–78.
[31] C. Lee, W. Yang, R. Parr, Phys. Rev. B 37 (1988) 785–789.
[32] A. D. Becke, J. Chem. Phys. 98 (1993) 5648–5652.
[33] P. A. M. Dirac, Proc. R. Soc. A (1929) 714–733.
[34] J. C. Slater, Phys. Rev. 81 (1951) 385.
[35] J. P. Perdew, Y. Wang, Phys. Rev. B 45 (1992) 13244.
[36] J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett. 77 (1996) 3865.
[37] J. P. Perdew, M. Ernzerhof, K. Burke, J. Chem. Phys. 105 (1996) 9982–
9985.
[38] N. C. Handy, A. J. Cohen, Mol. Phys. 99 (2001) 403–412.
[39] S. Vosko, L. Wilk, M. Nusair, Can. J. Phys. 58 (1980) 1200–1211.
[40] A. D. Becke, Phys. Rev. A 38 (1988) 3098.
[41] J. P. Perdew, Phys. Rev. B 33 (1986) 8822.
[42] D. A. Pantazis, X.-Y. Chen, C. R. Landis, F. Neese, J. Chem. Theory
Comput. 4 (2008) 908–919.
[43] M. A. d. Farias, M. d. C. Gonçalves, Polímeros 26 (1) (2016) 1–10.
[44] M. E. Voss, C. M. Beer, S. A. Mitchell, P. A. Blomgren, P. E. Zhichkin,
Tetrahedron 64 (2008) 645–651.
[45] N. T. Zanvettor, D. H. Nakahata, R. E. de Paiva, M. A. Ribeiro, A. Cuin,
P. P. Corbi, A. L. B. Formiga, Inorg. Chim. Acta 443 (2016) 304–315.
[46] A. B. P. Lever, Inorganic Electronic Spectroscopy, 2nd Edition, Elsevier,
1986.
23

[47] M. Scarpellini, A. Neves, E. E. Castellano, D. W. Franco, J. Mol. Struct.
694 (2004) 193–198.
[48] M. Delower Hossain, R. Ueno, M.-a. Haga, Inorg. Chem. Commun. 3 (2000)
35–38.
[49] A. W. Addison, T. N. Rao, J. Reedijk, J. van Rijn, G. C. Verschoor, J.
Chem. Soc., Dalton Trans. (1984) 1349–1356.
[50] P. C. Christidis, C. A. Bolos, G. St. Nikolov, Inorg. Chim. Acta 237 (1995)
123–130.
[51] G. Bernardinelli, G. Hopfgartner, A. F. Williams, Acta Crystallogr., Sect.
C: Cryst. Struct. Commun. 46 (1990) 1642–1645.
[52] D. H. Nakahata, M. A. Ribeiro, P. P. Corbi, D. Machado, M. Lancellotti,
W. R. Lustri, A. M. da Costa Ferreira, A. L. Formiga, Inorg. Chim. Acta
458 (2017) 224–232.
[53] E. Coronado, M. Gimenez-Marques, G. M. Espallargas, L. Brammer, Na-
ture Comm. 3 (2012) 1827/1–1827/8.
[54] F. R. G. Bergamini, M. A. Ribeiro, P. C. M. L. Miranda, A. L. B. Formiga,
P. P. Corbi, Acta Cryst. C 72 (2016) 544–548.
[55] B. S. Hammes, B. J. Damiano, P. H. Tobash, M. J. Hidalgo, G. P. Yap,
Inorg. Chem. Commun. 8 (2005) 513–516.
[56] M. G. G. Fuchs, S. Dechert, S. Demeshko, U. Ryde, F. Meyer, Inorg. Chem.
49 (2010) 5853–5858.
[57] F. G. Mutti, M. Gullotti, L. Casella, L. Santagostini, R. Pagliarin, K. K.
Andersson, M. F. Iozzi, G. Zoppellaro, Dalton Trans. 40 (2011) 5436–5457.
[58] F. G. Mutti, G. Zoppellaro, M. Gullotti, L. Santagostini, R. Pagliarin,
K. K. Andersson, L. Casella, Eur. J. Inorg. Chem. 2009 (2009) 554–566.
24

[59] Y. Sikdar, R. Modak, D. Bose, S. Banerjee, D. Bienko, W. Zierkiewicz,
A. Bienko, K. Das Saha, S. Goswami, Dalton Trans. 44 (2015) 8876–8888.
[60] W. E. Marsh, K. C. Patel, W. E. Hatfield, D. J. Hodgson, Inorg. Chem. 22
(1983) 511–515.
[61] W. E. Hatfield, Comments Inorg. Chem. 1 (1981) 105–121.
[62] W. A. Alves, R. H. de Almeida Santos, A. Paduan-Filho, C. C. Becerra,
A. C. Borin, A. M. D. C. Ferreira, Inorg. Chim. Acta 357 (2004) 2269–2278.
[63] K. Skorda, T. C. Stamatatos, A. P. Vafiadis, A. T. Lithoxoidou, A. Terzis,
S. P. Perlepes, J. Mrozinski, C. P. Raptopoulou, J. C. Plakatouras, E. G.
Bakalbassis, Inorg. Chim. Acta 358 (2005) 565–582.
[64] I. Lumb, M. S. Hundal, M. Corbella, V. Gómez, G. Hundal, Eur. J. Inorg.
Chem. 2013 (2013) 4799–4811.
[65] S. J. Brown, X. Tao, T. A. Wark, D. W. Stephan, P. K. Mascharak, Inorg.
Chem. 27 (1988) 1581–1587.
[66] T. Soda, Y. Kitagawa, T. Onishi, Y. Takano, Y. Shigeta, H. Nagao,
Y. Yoshioka, K. Yamaguchi, Chem. Phys. Lett. 319 (2000) 223–230.
[67] J.-S. Wang, K. Matyjaszewski, J. Am. Chem. Soc. 117 (1995) 5614–5615.
[68] T. E. Patten, K. Matyjaszewski, Acc. Chem. Res. 32 (1999) 895–903.
[69] U. S. Schubert, G. Hochwimmer, C. E. Spindler, O. Nuyken, Polym. Bull.
43 (1999) 319–326.
[70] J.-S. Wang, K. Matyjaszewski, Macromolecules 28 (23) (1995) 7901–7910.
[71] S. Perrier, P. Takolpuckdee, J. Polym. Sci. A Polym. Chem. 43 (22) (2005)
5347–5393.
[72] B. Ray, M. Kotani, S. Yamago, Macromolecules 39 (16) (2006) 5259–5265.
25

[73] M. U. Kahveci, G. Acik, Y. Yagci, Macromol. Rapid Commun. 33 (4) (2012)
309–313.
[74] S. Chavda, S. Yusa, M. Inoue, L. Abezgauz, E. Kesselman, D. Danino,
P. Bahadur, Eur. Polym. J. 49 (1) (2013) 209–216.
[75] M. Zhong, K. Matyjaszewski, Macromolecules 44 (8) (2011) 2668–2677.
[76] M. S. Saraiva, C. D. Nunes, T. G. Nunes, M. J. Calhorda, J. Mol. Catal.
A: Chem. 321 (1-2) (2010) 92–100.
[77] A. O. Eseola, W.-H. Sun, W. Li, J. A. Woods, J. Mol. Struct. 984 (1-3)
(2010) 117–124.
[78] F. S. P. Cardoso, K. A. Abboud, A. Aponick, J. Am. Chem. Soc. 135 (39)
(2013) 14548–14551.
[79] S. Khabnadideh, Z. Rezaei, A. Khalafi-Nezhad, R. Bahrinajafi, R. Mo-
hamadi, A. Farrokhroz, Bioorg. Med. Chem. Lett. 13 (17) (2003) 2863–
2865.
26

ꢀ

• A dimeric Cu(II) complex was characterized by single crystal XRD
• Magnetic interaction between copper ions is ferromagnetic
• DFT calculations confirm the magnetic coupling through chloride bridges
• Essays confirms that the complex is a catalyst for ATRP polymeriza-
tion
1