New heterobimetallic Cu(II)/Mn(II) complexes with trans-1,8-cyclam derivatives: Synthesis, characterization, magnetic properties and crystal structures of (μ2-Chloro)-(dpc)-copper(II)-trichloro-manganese(II) and two polymorphs of (μ2-Chloro)-(dac)-copper(II)-trichloro-manganese(II)

Article abstract of DOI:10.1016/j.molstruc.2021.130592

Two derivatives of cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane) with propyl- or allyl- (prop-2-en-1-yl) substituents on nitrogen atoms in trans positions, namely 1,8-dipropyl-1,4,8,11-tetraazacyclotetradecane (dpc) and 1,8-diallyl-1,4,8,11-tetraazacyclotetradecane (dac) were prepared and characterized by IR, ¹H NMR and ¹³C NMR spectroscopy. Reaction of dpc and dac with copper(II) chloride gives compounds [Cu(dpc)(H₂O)₂]Cl₂ (1) and [Cu(dac)(H₂O)₂]Cl₂ (3) with similar crystal structures. Compounds 1 and 3 were used as precursors in the synthesis of Cu(II)/Mn(II) complexes 2, 4a and 4b. Prepared complexes were characterized by IR spectroscopy, elemental analysis and their crystal structures were determined using single crystal X-ray analysis. Compounds 4a and 4b are polymorphs, both crystallize in the monoclinic crystal system and the main difference in their crystal structures is in steric arrangement of metal centres within a chain. Moreover, measurements of magnetic susceptibility and Broken Symmetry DFT calculations (BS DFT calculations) carried out for bimetallic complexes 2 and 4a showed that a ferromagnetic exchange interaction J/k_B = 2.28 K and J/k_B = 2.34 K, respectively, exists within the dinuclear units.

Full text of DOI:10.1016/j.molstruc.2021.130592

Journal of Molecular Structure 1241 (2021) 130592
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstr
New heterobimetallic Cu(II)/Mn(II) complexes with trans-1,8-cyclam
derivatives: Synthesis, characterization, magnetic properties and
crystal structures of (μ -Chloro)-(dpc)-copper(II)-trichloro-
2
manganese(II) and two polymorphs of (μ -Chloro)-(dac)-copper(II)-
2
trichloro-manganese(II)
a
b,∗
c
a
ˇ
Erika Samoľová , Juraj Kuchár , Erik Cižmár , Michal Dušek
a
Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, Praha 16253, Czech Republic
Department of Inorganic Chemistry, Pavol Jozef Šafárik University in Košice, Moyzesova 11, Košice 04154, Slovak Republic
Department of Condensed Matter Physics, Pavol Jozef Šafárik University in Košice, Park Angelinum 9, Košice 04154, Slovak Republic
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
Two derivatives of cyclam (cyclam
=
1,4,8,11-tetraazacyclotetradecane) with propyl- or allyl-
Received 2 February 2021
Revised 28 April 2021
Accepted 29 April 2021
Available online 5 May 2021
(
prop-2-en-1-yl) substituents on nitrogen atoms in trans positions, namely 1,8-dipropyl-1,4,8,11-
tetraazacyclotetradecane (dpc) and 1,8-diallyl-1,4,8,11-tetraazacyclotetradecane (dac) were prepared and
characterized by IR, 1H NMR and 13 C NMR spectroscopy. Reaction of dpc and dac with copper(II) chlo-
ride gives compounds [Cu(dpc)(H2O)2]Cl2 (1) and [Cu(dac)(H2O)2]Cl2 (3) with similar crystal structures.
Compounds 1 and 3 were used as precursors in the synthesis of Cu(II)/Mn(II) complexes 2, 4a and 4b.
Prepared complexes were characterized by IR spectroscopy, elemental analysis and their crystal struc-
tures were determined using single crystal X-ray analysis. Compounds 4a and 4b are polymorphs, both
crystallize in the monoclinic crystal system and the main difference in their crystal structures is in steric
arrangement of metal centres within a chain. Moreover, measurements of magnetic susceptibility and
Broken Symmetry DFT calculations (BS DFT calculations) carried out for bimetallic complexes 2 and 4a
showed that a ferromagnetic exchange interaction J/kB = 2.28 K and J/kB = 2.34 K, respectively, exists
within the dinuclear units.
Keywords:
Heterobimetallic complexes
Cyclam derivatives
Crystal structure
Magnetic properties
©
2021 Elsevier B.V. All rights reserved.
1
. Introduction
is of ferromagnetic (FM) nature with non-zero spontaneous mag-
netization. However, excitations are of AFM type [11] leading to
the formation of magnetization plateaus and a large change of the
magnetic entropy at the field-induced quantum-critical points [12].
For synthetic chemists, the targeted synthesis of coordina-
tion polymers remains the challenge for the last decades. We
are interested in synthesis, characterization, and the study of
magnetic properties of complexes with a 1D structure based on
Cu(II) coordinated by N-donor ligands in equatorial positions and
Magnetic phenomena associated with thermal effects have re-
cently become relevant not only for solving fundamental problems
in magnetism and solid-state physics but also for technological
applications [1]. One such phenomenon is the magnetocaloric ef-
fect that can be used in the thermal study of magnetic properties
of compounds, or for practical use, for example in magnetic refrig-
erators [2,3]. There are several ferrimagnetic complexes in which
the magnetocaloric effect was observed [4,5]. It was predicted
by Kahn et al. that systems based on one-dimensional bimetallic
chains with alternating Cu(II) and Mn(II) atoms participating in
antiferromagnetic (AFM) exchange interaction should show ferri-
magnetic behavior [6,7] and this prediction has been confirmed in
many complexes [8–10]. The ground state of ferrimagnetic chains
{MnCl } particle. The key step in their synthesis is the selection
4
of ligands, as they significantly influence the formation of chains
and their arrangement in the crystal structure. Previously, we
prepared series of complexes with Cu(II) atom coordinated by
N-derivatives of ethane-1,2-diamine (Samoľová, private commns.)
in equatorial positions and chloride ligands in axial positions, the
latter mediating the connection with Mn(II) atom that becomes
tetracoordinated by chlorido ligands. Such an arrangement allows
the formation of bimetallic chains with short chloride-bridged
∗
Corresponding author.
E-mail address: juraj.kuchar@upjs.sk (J. Kuchár).
https://doi.org/10.1016/j.molstruc.2021.130592
0
022-2860/© 2021 Elsevier B.V. All rights reserved.

E. Samoľová, J. Kuchár, E. Cˇ ižmár et al.
Journal of Molecular Structure 1241 (2021) 130592
paramagnetic metals. For the preparation of this class of com-
plexes, we choose the complex-as-ligand strategy, where Cu(II)
complexes with N-donor ligands are prepared in the first step and
then used in the reaction with Mn(II) chloride.
dibromide was dissolved in 250 ml 3M NaOH and stirred for 3 h,
consequently extracted with CH Cl , the extract was dried with
2
2
anhydrous MgSO , filtered and the solvent was removed by dis-
4
tillation under vacuum. Ligands dac and dbc prepared using this
method were characterized by IR spectroscopy, 1H and 13C NMR
spectroscopy.
In this paper, we focused on the preparation and characteriza-
tion of analogous compounds using macrocyclic ligands based on
cyclam in the copper(II) coordination sphere. It is well known that
copper(II) forms with this class of ligands complexes with appre-
ciable kinetic and thermodynamic stability. This makes them con-
venient for the use of complex-as-ligand strategy by the prepara-
tion of bimetallic complexes. Although compounds 2 and 4a can
be regarded as chain-like alternating-spin systems, the major ex-
change interaction mediated by covalent bonds in Cu(II)-Mn(II)
units is FM as suggested by our magnetic measurements and Bro-
ken Symmetry (BS) DFT calculations.
dac
1
H NMR (400 MHz, CDCl ) δ 5.87 (tdd, J = 23.7, 10.3, 6.7 Hz,
3
2H, CH =CH-), 5.21 – 5.16 (m, 2H, CH =CH-), 5.16 – 5.14 (m,
2
2
J = 2.3 Hz, 2H, CH =CH-), 3.16 (s, 2H, NH), 3.12 (d, J = 6.7 Hz,
2
4H, CH =CH-CH ), 2.73 – 2.63 (m, 8H, α-CH ), 2.57 – 2.49 (m, 8H,
2
2
2
α-CH ), 1.80 – 1.73 (m, 4H, β-CH )
2
2
13
C NMR (101 MHz, CDCl ) δ = 134.72 (CH =CH-), 117.99
3
2
(CH =CH-), 56.64 (α-CH ), 53.61
2
2
(α-CH ), 53.07 (α-CH ), 50.55 (α-CH ), 47.70 (α-CH ), 25.78 (β-
2
2
2
2
CH2)
2
. Experimental
IR: ν(NH) 3297 (w), ν(=C-H) 3073 (vw), ν(CH) 2921 (m), 2800
(
m), ν(C=C) 1643 (w), δ(CH ) 1458 (m), 1332 (m), ν(CN) 1130 (m),
2
2
.1. Materials and physical measurements
All reagents and solvents except ligands dac and dpc were pur-
ω(CH ) 913 (s)
2
Yield: 1.3 g (52%)
dpc
1
chased from commercial sources and used without further pu-
rification. Infrared spectra were recorded on a Nicolet 6700 FT-IR
spectrometer using ATR technique in the range of 4000–400 cm–1
H NMR (400 MHz, CDCl ) δ 3.35 (s, 2H, NH), 2.75 – 2.60 (m,
3
8H, α-CH ), 2.55 – 2.45 (m, 8H, α-CH ), 2.43 – 2.36 (m, 4H, -CH -
2
2
2
.
CH -CH ), 1.79 – 1.71 (m, 4H, β-CH ), 1.49 (dq, J = 14.8, 7.4 Hz,
2
3
2
Elemental analyses (C, H, N) were performed on a CHNS Elementar
Analyzer VarioMICRO by Elementar Analysensysteme GmbH. 13C
NMR spectra of dac and dpc were obtained on a Bruker Ascent 400
spectrometer. Chemical shifts are given in ppm using tetramethyl-
silane as a standard.
4H, -CH -CH -CH ), 0.86 (t, 6H, -CH ).
2 2 3 3
13
C NMR (101 MHz, CDCl ) δ = 53.76 (α-CH ), 51.82 (α-CH ),
3
2
2
51.38 (α-CH ), 48.56 (α-CH ), 46.62 (α-CH ), 29.27 (-CH -CH ),
2
2
2
2
3
22.95 (β-CH ), 11.86 (CH )
2
3
IR: ν(NH) 3279 (vw), ν(CH) 2957 (w), 2931 (w), 2873 (w)
2805(m), δ(CH ) 1459 (m), 1381 (w), ν(CN) 1164 (m), ω(CH )
744 (s)
Susceptibility (estimated as the ratio of measured magnetic mo-
ment and applied magnetic field) and magnetization was measured
on a commercial Quantum Design MPMS3 magnetometer in the
temperature range from 1.8 to 300 K at 100 mT. A nascent poly-
crystalline specimen was fixed in a gelatine capsule and the cap-
sule was held by a straw. The signal contribution of the gelatine
capsule and the diamagnetic contribution of the sample (estimated
using Pascal’s constants [13]) were subtracted.
2
2
Yield: 1g (31.5%)
Synthesis of [Cu( dpc)(H O) ]Cl (1)
2
2
2
0.8 g of dpc (2.81 mmol) were dissolved in 70 ml of ethanol
and heated to 65 °C. The solution of 0.48
g
CuCl ·2H O
2
2
(2.81 mmol, p.a., Merck) in 20 ml of ethanol was added
slowly, and the resulting solution was stirred at the same
temperature for one hour, then filtered and the solution
was allowed to crystallize at room temperature. In two
weeks dark-violet crystals of 1 were formed and collected by
filtration.
2
.2. Synthesis and crystallization
Ligands dac and dpc
The organic ligands dac and dpc were prepared according to the
CHN (calc./exp.): C: 42.24/42.43; H: 8.86/8.35; N: 12.31/12.57
IR: ν(OH) 3442 (w), ν(NH) 3176 (m), 3131(m), ν(CH) 2958 (m),
synthetic procedure (Scheme 1) described previously by Royal et al.
14]. 2 g of cyclam (99% purity, Merck) were dissolved in 100 ml of
[
2
878 (m), δ(OH ) 1636 (w), δ(NH) 1474 (m), 1463 (m), δ(CH ) 1426
2 2
distilled water, and the solution was cooled to 0 °C with continu-
ous stirring. 3.24 ml of formaldehyde (20 % molar excess, Merck,
(
m), 1390 (w), ν(CN) 1104 (m)
Synthesis of Cu( dpc)MnCl4 (2)
3
7% solution in H O) was rapidly added, and the stirring contin-
2
0.27 g (0.59 mmol) of 1 was dissolved in 40 ml of ethanol
ued for 2 h. Formed white precipitate was filtered and dried at 60
and heated to 65 °C. The solution of 0.12 g MnCl ·4H O (0.59
2
2
°C. The dry precipitate was dissolved in acetonitrile, and 3 equiv.
mmol, p.a., Merck) in 10 ml of ethanol was slowly added, and
the resulting solution was refluxed for 3 h. The formed violet pre-
cipitate was filtered hot and dried on air. Dark red crystals of
of 3-bromopropene (99% purity, Merck,) or 1-bromopropane (99%
purity, Merck,) were rapidly added with continuous stirring. The
reaction mixture was stirred 2 h for 3-bromopropene and 2 days
in the case of 1-bromopropane, formed colourless precipitate was
filtered, washed with acetonitrile and dried on air. 1 g of prepared
compound 1,8-dipropyl-4,11-diazoniatricyclo[9.3.1.14,8]-hexadecane
dibromide or 1,8-diallyl-4,11-diazoniatricyclo[9.3.1.14,8]hexadecane
2
were obtained within one week by recrystallization of precipi-
tate from ethanol using diffusion of acetone vapor. The crystalline
product was used for measurements of magnetic susceptibility and
magnetization.
Scheme 1. Synthetic route for the ligand synthesis.
2

E. Samoľová, J. Kuchár, E. Cˇ ižmár et al.
Journal of Molecular Structure 1241 (2021) 130592
Table 1
Crystal data and results of the refinement.
1
2
3
4a
4b
Crystal data
Chemical formula
C16H40Cl2Cu N4O2
C16H36Cl4Cu MnN4
544.8
C16H36Cl2Cu N4O2
450.9
C16H32Cl4Cu MnN4
540.8
C16H32Cl4Cu MnN4
540.8
Mr
455
Crystal system, space group
Triclinic, P–1
150
Monoclinic, P21/n
95
Triclinic, P–1
170
Monoclinic, P21/n
120
Monoclinic, P21/c
170
Temperature (K)
a, b, c ( A˚ )
7.9494 (6), 8.5551 (6),
9.2800 (2), 17.4845
(3), 14.6176 (3)
90, 102.110 (2), 90
7.7409 (4), 8.4657 (4),
8.8343 (3)
9.3198 (3), 16.7006
(4), 14.4346 (6)
90, 94.162 (3), 90
14.7060 (3), 19.3297 (5),
16.3937 (4)
8
.6372 (4)
92.055 (5), 106.840
5), 110.813 (6)
α, β, γ (°)
93.819 (3), 106.905
(4), 111.114 (4)
507.12 (5)
90, 94.854 (2), 90
(
V ( A˚ 3)
519.16 (7)
2319.02 (8)
2240.75 (13)
4643.40 (19)
Z
1
4
1
4
8
Radiation type
μ (mm-1)
Crystal size (mm)
Mo Kα
1.33
Cu Kα
9.86
Mo Kα
1.36
Cu Kα
10.21
Mo Kα
1.93
0.24 × 0.12 × 0.09
0.47 × 0.09 × 0.04
0.22 × 0.16 × 0.09
0.32 × 0.07 × 0.05
0.23 × 0.17 × 0.07
Data collection
Diffractometer
SuperNova, Dual, Cu at SuperNova, Dual, Cu at Xcalibur, Sapphire2,
Xcalibur, AtlasS2,
Gemini ultra
Xcalibur, Sapphire2, large
Be window
home/near, AtlasS2
Multi-scan [15]
home/near, AtlasS2
Multi-scan [15]
large Be window
Multi-scan [15]
Absorption correction
Multi-scan [15]
Analytical numeric
absorption correction [19].
0.761, 0.916
Tmin, Tmax
0.925, 1
0.32, 1
0.883, 1
0.412, 1
No. of measured, independent
and observed [I > 3σ(I)]
reflections
9105, 2598, 2331
38010, 4686, 4343
11247, 2514, 2002
23492, 3123, 2833
24618, 9627, 5839
Rint
0.022
0.698
0.043
0.624
0.031
0.690
0.063
0.600
0.037
0.692
sin θ/λ)max ( A˚ 1
−
)
(
Refinement
R[F2 > 2σ(F )], wR(F ), S
2
2
0.023, 0.061, 1.59
0.024, 0.060, 1.61
0.028, 0.062, 1.37
0.030, 0.075, 1.94
0.039, 0.091, 1.31
No. of reflections
2598
4686
2514
3123
9627
No. of parameters
No. of restraints
124
241
124
243
481
3
2
3
2
4
max, ρmin (e· A˚ −3)
ρ
0.31, -0.23
0.49, -0.43
0.37, -0.34
0.42, -0.39
0.82, -0.88
CHN (calc/exp.): C: 35.28/34.59; H: 6.66/6.48; N: 10,28/9.99
lowed to crystallize at room temperature. Within one week, dark-
violet crystals of 3 were formed and collected by filtration.
CHN (calc/exp): C: 42.62/42.81; H: 8.05/8.13; N: 12.42/12.37
IR: ν(OH) 3323 (w), ν(NH) 3183 (w), ν(CH) 3095 (w), 2916 (s),
2848 (s), ν(C=C) 1638 (w), δ(OH ) 1611 (w), δ(CH ) 1463 (s), 1421
IR: ν(NH) 3184 (w), 3160 (m), ν(CH) 2961 (m), 2941 (m), 2877
(
m), δ(NH) 1475 (m), 1469 (m), δ(CH ) 1428 (m), 1384 (w), ν(CN)
2
1
102 (m)
Synthesis of [Cu( dac)(H O) ]Cl (3)
2
2
2
2
2
1.2 g of dac (4.28 mmol) was dissolved in 70 ml of ethanol and
(m), ν(CN) 1064 (m)
Synthesis of Cu( dac)MnCl4 (4a)
heated to 65 °C. The solution of 0.73 g CuCl ·2H O (4.28 mmol,
2
2
p.a., Merck) in 20 ml of ethanol was added slowly, and the re-
sulting solution was stirred at the same temperature for one hour,
then formed violet precipitate was filtered and the solution was al-
0.5 g of 3 (1.11 mmol) was dissolved in 100 ml of ethanol and
heated to 65 °C. The solution of 0.22 g MnCl ·4H O (1.11 mmol,
2
2
p.a., Merck) in 10 ml of ethanol was slowly added, and the result-
ing solution was refluxed for 3 h. The formed violet precipitate was
Fig. 1. The structure motif in 1. Thermal ellipsoids are drawn on the 50 % proba-
Fig. 2. The structure motif in 3. Thermal ellipsoids are drawn on the 50 % proba-
bility level.
bility level.
3

E. Samoľová, J. Kuchár, E. Cˇ ižmár et al.
Journal of Molecular Structure 1241 (2021) 130592
Fig. 3. Schematic view of the hydrogen bond system in 1. i: 1-x, 1-y, 1-z; ii: 1+x, y, z.
filtered hot and dried on air. Dark red crystals of 4a were obtained
within one week by recrystallization of precipitate from ethanol
using diffusion of acetonitrile vapor. The crystalline product was
used for measurements of magnetic susceptibility and magnetiza-
tion.
IR: ν(NH) 3136 (w), ν(CH) 2941 (w), 2878 (w), ν(C=C) 1640
(vw), δ(CH ) 1460 (m), 1429 (m), ν(CN) 1101 (m)
2
2.3. Refinement
CHN (calc/exp): C: 35,54/35,3; H: 5,96/5,99; N: 10,36/10,14
IR: ν(NH) 3170 (w), 3153 (m), ν(CH) 2976 (w), 2951 (w), 2917
Single crystal experiments were carried out on a four-circle κ
axis Xcalibur2 diffractometer equipped with a CCD detector Sap-
phire 2 (Rigaku OD) using MoKα radiation for 3 and 4b, four-circle
diffractometer Supernova (Rigaku OD) equipped with a CCD de-
tector Atlas S2 using CuKα for 1 and 2, and four-circle diffrac-
tometer Gemini using CuKα radiation for 4a. Because the measure-
ments were undertaken with different chillers allowing for differ-
ent optimal lowest temperatures, the data were acquired at dif-
ferent temperatures, which is nevertheless acceptable due to the
absence of phase transition effects. The CrysAlisPro [15] software
was used for data collection, reduction, and correction for absorp-
(
(
w), 2873 (w), ν(C=C) 1636 (w), δ(CH ) 1469 (m), 1456 (m), 1427
2
m), 1417 (w), ν(CN) 1099 (m)
Synthesis of Cu( dac)MnCl4 (4b)
0
.255 g (0.61 mmol) of 3 was dissolved in ethanol (50 ml),
MnCl ·4H O (0.12 g, 0.61 mmol, p.a., Merck) was added, and the
2
2
resulting solution was heated under reflux for 3 h, then filtered hot
and allowed to crystallize at room temperature. Within one week
red crystals of 4b were formed and collected by filtration.
CHN (calc./exp): C: 35.29/34.94; H: 5.92/6.02; N: 10.29/10.03
Table 2
Geometrical parameters characterizing coordination sphere of Cu(II) atom in
1
and 3.
1
3
Cu1-N1
2.1051(10)
1.9981(12)
2.5647(14)
86.77(4)
2.0049(14)
2.0092(14)
2.5676(18)
86.24(6)
Cu1-N2
Cu1-O1
N1-Cu1-N2
O1-Cu1-N1
O1-Cu1-N2
95.37(6)
87.255(6)
84.049(6)
93.20(6)
Table 3
Hydrogen bonding parameters in 1 and 3.
D-H···A
D-H
H···A
D···A
D-H···A
i
1
O1-H1O1···Cl1
0.849(16)
0.870(11)
0.850(14)
2.343(15)
2.432(11)
2.300(14)
3.1825(12)
3.2979(16)
3.1488(12)
169.6(17)
173.3(12)
177.1(14)
ii
N2-H1N2···Cl1
O1-H2O1···Cl1
i: 1-x, 1-y, 1-z; ii: 1+x, y, z
i
3
O1-H1O1···Cl1
O1-H2O1···Cl1
0.850(19)
0.850(16)
0.870(14)
2.321(18)
2.323(16)
2.444(14)
3.1597(16)
3.1711(15)
3.3092(18)
169.1(19)
176.2(15)
173.1(17)
ii
N2-H1N2···Cl1
Fig. 4. The bimetallic complex in 2. Thermal ellipsoids are drawn on the 50 % prob-
i: 1-x, -y, 1-z; ii: x-1, y, z
ability level.
4

E. Samoľová, J. Kuchár, E. Cˇ ižmár et al.
Journal of Molecular Structure 1241 (2021) 130592
Fig. 5. Hydrogen bonds in the crystal structure of 2. ii: ½+x, ½-y, -½+z.
tion for all compounds. In all cases, the model was found using Su-
perflip [16]. An anisotropic refinement by full-matrix least-squares
was performed with JANA2006 [17]. Non-hydrogen atoms were re-
fined with anisotropic ADPs, and the hydrogen atoms on carbon
atoms were placed at calculated positions refined on parent atoms.
Hydrogens of nitrogen atoms and water molecules were found in a
difference Fourier map and refined in the riding mode using bond
the overall values of atomic displacement parameter (ADP). Experi-
mental details: H atoms were treated by a mixture of independent
and constrained refinement.
2.4. Computational details
The BS DFT calculation [20] was performed using the ORCA
4.0.1 computational package [21]. The calculation was done us-
ing the PBE0 exchange-correlation functional [22]. The zeroth-
order regular approximation (ZORA) [23,24] together with the
scalar relativistic contracted version of basis functions Def2-TZVP(-
f) [25] was used. The calculations utilized the RI approximation
and the chain-of-spheres (RIJCOSX) approximation to exact ex-
change [26] with appropriate decontracted auxiliary basis sets
[27,28]. Increased integration grids (Grid4 and GridX4) and tight
SCF convergence criteria were used. The exchange coupling was
˚
˚
restraint 0.87 A for N-H and 0.85 A for O-H, with s.u. of both re-
straints being 0.001. Crystal data and parameters of the structure
refinement for all compounds are summarized in Table 1. The fig-
ures of structures were drawn using the DIAMOND software [18].
In the case of 4a, the crystals were twinned, and for structure re-
finement, the reflections of a stronger domain and twinning ma-
trix were used. Using the twinning matrix, differences in theta be-
tween reflections of both domains were calculated and sorted to
the following shells: 0.0–0.1 - fully overlapped reflections, 0.1–0.3 -
no reflections, 0.3–0.4–870 partially overlapped reflections (out of
E
−E
−S
HS
BS
obtained using the Yamaguchi formalism [29] JBS = − S2
2
HS
BS
3
993 independent reflections), 0.4–0.6 - no reflections. Discard-
from single-point approach (using X-ray determined structure),
ing the 870 partially overlapped reflections improved R, GOF, and
Table 4
Geometrical parameters characterizing coordination sphere of central atoms Cu(II)
and Mn(II) in 2.
Cu1-N1
2.1049(13)
N1-Cu1-N2
87.04(5)
Cu1-N2
1.9998(14)
2.0784(13)
1.9943(13)
2.8341(1)
2.3907(5)
2.3478(6)
2.3588(5)
2.3721(4)
174.17(6)
93.21(5)
N1-Cu1-N3
174.09(6)
Cu1-N3
N2-Cu1-N3
92.82(5)
Cu1-N4
N3-Cu1-N4
86.33(5)
Cu1-Cl1
Cl1-Mn41-Cl4
Cl1-Mn1-Cl3
Cl1-Mn1-Cl2
Cl4-Mn1-Cl3
Cl4-Mn1-Cl2
Cl3-Mn1-Cl2
Cu1-Cl1-Mn1
105.962(18)
108.435(16)
112.729(18)
116.979(16)
106.527(17)
106.38(2)
Mn1-Cl1
Mn1-Cl2
Mn1-Cl3
Mn1-Cl4
N2-Cu1-N4
N1-Cu1-N4
121.628(1)
Table 5
Hydrogen bonding parameters in 2.
D-H···A
D-H
H···A
D···A
D-H···A
ii
N2-H1N2···Cl1
N4-H1N4···Cl4
0.870(14)
0.870(16)
2.724(19)
2.490(19)
3.4999(16)
3.3189(16)
149.2(15)
159.5(15)
Fig. 6. The complex molecule in 4a. Thermal ellipsoids are drawn on the 50 % prob-
ability level.
ii: 1/2+x, 1/2-y, z-1/2
5

E. Samoľová, J. Kuchár, E. Cˇ ižmár et al.
Journal of Molecular Structure 1241 (2021) 130592
ˆ ˆ
1 2
of water molecules and the basal ones by the nitrogen atoms
with a spin Hamiltonian in the form H = −2J S S (in the com-
BS
parison with the experimental data a spin Hamiltonian in the form
from macrocyclic ligand dpc or dac (Figs. 1, 2). Cu-O distances are
2.5647(14) A˚ in 1 and 2.5685(17) A˚ in 3, and they are compara-
ˆ ˆ
H = −JS S was used).
1
2
ble to distances in complexes with similar structure motif regis-
˚
tered in CCDC with cyclam (2.535 A) [31] or its derivatives (2.569
3
. Results and discussion
˚
˚
A, 2.67 A) [32,33]. In both cases, the coordinated macrocycle is in
the trans-III configuration, which is usually the most stable con-
figuration for such type of metal complexes [34]. Geometric pa-
rameters characterizing the coordination polyhedrons in both com-
plexes are summarized in Table 2. In the crystal structure of 1 and
3, aqua ligands, chloride anions, and amine groups of macrocycles
participate in the hydrogen bond system including the O-H···Cl and
N-H···Cl hydrogen bonds with moderate strength, considered due
to the D-A distance length, angles values, and calculated hydro-
gen bond energies [35]. Two ring patterns can be described for
Reaction of dpc and dac with copper(II) chloride gives com-
pounds [Cu(dpc)(H O) ]Cl
(1) and [Cu(dac)(H O) ]Cl
(3),
diaqua-((1,8-dipropyl-1,4,8,11-tetraazacyclotetradecane-
κ N)-copper(II) chloride) and diaqua-((1,8-diallyl-1,4,8,11-
tetraazacyclotetradecane-κ N)-copper(II) chloride), with sim-
ilar crystal structures. Compounds and were used as
2
2
2
2
2
2
namely
4
4
1
3
precursors in the synthesis of Cu(II)/Mn(II) complexes, (μ2-
4
Chloro)(1,8-dipropyl-1,4,8,11-tetraazacyclotetradecane-κ N)-
copper(II)-trichlorido-manganese(II) (2) and two polymorphs
1
2
4
the hydrogen bond system: R (6) including Cu(II) atom, one amine
of (μ -Chloro)-(1,8-diallyl-1,4,8,11-tetraazacyclotetradecane-κ N)-
copper(II)-trichlorido-manganese(II) (4a and 4b) differ in steric
2
group of ligand, chloride anion, oxygen atom and one hydrogen
2
2
atom from water molecule, and R (8) including two coordinated
arrangement of metal centres within a chain.
water molecules and two chloride anions [36]. The connections of
complexes through the hydrogen bond system propagate in a di-
rection. Schematic representation of hydrogen bonds in 1 is shown
in Fig. 3, and geometrical parameters for both compounds can be
found in Table 3. The described hydrogen bond system has been al-
ready observed in other copper(II) complexes with cyclam deriva-
tives [37–39].
3
.1. Synthesis
The strategy used for preparing bimetallic complexes can be
considered as building blocks synthesis and was carried out us-
ing a slightly modified synthetic procedure published earlier [30].
In the first step, the ligand dpc or dac was added to the ethano-
[
Cu(dpc)MnCl ] (2)
4
lic solution of CuCl , and crystallization from the resulting solution
2
The structure of 2 consists of binuclear complexes where Mn(II)
and Cu(II) ions are bridged by chlorido ligand. The steric arrange-
ment of chlorido ligands in Mn(II) coordination environment is
gave compound 1 or 3. Both were characterized and used as start-
ing material in the second step of the synthesis, in which ethano-
lic solution of MnCl2 was added to the solution of copper(II) com-
plex in the same solvent, and the resulting solution was heated
under reflux for 3 h. For crystallization, two strategies were cho-
sen: slow evaporation of the solvent under standard conditions,
and diffusion of acetone vapour into the reaction mixture at the
same temperature. For the synthesis starting from 1, both crystal-
lization strategies lead to the preparation of the same product 2,
but in the case of the synthesis starting from 3, two polymorphs
Table 6
Geometrical parameters characterizing coordination sphere of central atoms Cu(II)
and Mn(II) in 4a and 4b.
4a
4b
Cu1-N1
2.064(3)
2.075(3)
Cu2-N5
2.048(3)
Cu1-N2
1.992(3)
1.997(3)
Cu2-N6
1.987(4)
of [Cu(dac)MnCl ] were obtained, 4a by diffusion technique and 4b
4
Cu1-N3
2.082(3)
2.052(3)
Cu2-N7
2.071(3)
by slow evaporation of the solvent.
Cu1-N4
1.999(3)
1.999(3)
Cu2-N8
1.989(3)
Cu1-Cl1
2.9453(9)
2.3909(9)
2.3488(10)
2.3383(9)
2.3844(8)
175.34(11)
92.75(11)
86.03(11)
175.23(11)
94.21(11)
86.63(11)
103.84(3)
114.41(3)
109.72(3)
108.30(3)
108.09(3)
111.99(4)
123.632(4)
2.8631(12)
2.3834(12)
2.3482(13)
2.3660(11)
2.3651(12)
174.46(14)
93.68(13)
86.84(13)
172.72(13)
92.58(13)
86.20(13)
107.13(4)
106.41(4)
113.91(4)
111.27(4)
110.27(5)
107.83(4)
120.24(3)
Cu2-Cl6
2.7988(12)
2.3431(12)
2.3815(12)
2.3669(11)
2.3657(12)
170.46(14)
86.09(14)
92.27(13)
94.65(14)
85.83(13)
172.86(15)
108.47(4)
109.16(4)
108.83(5)
105.99(5)
111.20(4)
113.06(4)
122.48(3)
Mn1-Cl1
Mn2-Cl5
3
.2. Crystal structures
Cu(dpc)(H O) ]Cl (1) and [Cu(dac)(H O) ]Cl (3)
Mn1-Cl2
Mn2-Cl6
Mn1-Cl3
Mn2-Cl7
[
2
2
2
2
2
2
Mn1-Cl4
Mn2-Cl8
Compounds 1 and 3 have a similar crystal structure that con-
N2-Cu1-N4
N1-Cu1-N4
N1-Cu1-N2
N1-Cu1-N3
N2-Cu1-N3
N3-Cu1-N4
Cl1-Mn1-Cl4
Cl1-Mn1-Cl3
Cl1-Mn1-Cl2
Cl4-Mn1-Cl3
Cl4-Mn1-Cl2
Cl3-Mn1-Cl2
Cu1-Cl1-Mn1
N5-Cu2-N7
N5-Cu2-N6
N5-Cu2-N8
N7-Cu2-N6
N7-Cu2-N8
N6-Cu2-N8
Cl7-Mn2-Cl8
Cl7-Mn2-Cl6
Cl7-Mn2-Cl5
Cl8-Mn2-Cl6
Cl8-Mn2-Cl5
Cl6-Mn2-Cl5
Cu2-Cl6-Mn2
sists of isolated Cu(II) complexes and uncoordinated chloride an-
ions. The shape of Cu(II) coordination polyhedron is tetragonal
bipyramidal with elongation in axial positions due to the Jahn-
Teller effect. Two axial positions are occupied by the oxygen atoms
Table 7
Hydrogen bonding parameters in 4a and 4b.
D-H···A
D-H
H···A
D···A
D-H···A
4
a
N2-H1N2···Cl4
0.870(3)
0.870(3)
2.44(3)
2.53(3)
3.272(3)
3.282(3)
158.89(3)
144.85(3)
i
i
N4 -H1N4 ···Cl4
i: 3/2-x, y-1/2, 1/2-z
4
b
N2-H1N2···Cl7
N4-H1N4···Cl3
N6-H1N6···Cl8
N8-H1N8···Cl4
0.870(15)
0.87(2)
2.485(15)
2.429(19)
2.423(14)
2.560(18)
3.294(4)
3.277(4)
3.267(4)
3.323(4)
155(3)
165(3)
164(4)
147(3)
0.870(11)
0.870(15)
ii
Fig. 7. The complex molecule in 4b. Thermal ellipsoids are drawn on the 50 % prob-
ii: x, y-1, z
ability level.
6

E. Samoľová, J. Kuchár, E. Cˇ ižmár et al.
Journal of Molecular Structure 1241 (2021) 130592
close to tetrahedral, an average value of Mn-Cl bond distances
4b. The Cu1-Cl1 distance in 4a of 2.9453(9) A˚ is close to the sum
˚
is 2.367(16) A, and the main deviation of tetrahedral symmetry
of Van der Waals radii. In 4b both Cu-Cl distances are slightly
is represented by the angle Cl4-Mn1-Cl3 with value 116.979(16)°.
Cu(II) atom is pentacoordinated, the axial position is occupied by
bridging chlorido ligand and four equatorial positions are occupied
by nitrogen atoms of dpc ligand. Similar to compounds 1 and 3,
the bridging ligand is in trans-III configuration (Fig. 4). Cu(II) is
shorter, Cu1-Cl1 2.8628(11) A˚ and Cu2-Cl6 2.7987(11) A˚ . Similar
to 2, Cu(II) is placed slightly above the plane defined by nitro-
gen atoms from dac, with the distance from the plane 0.0825(4)
A˚ for 4a, and 0.1141(5) A˚ and 0.1471(5) A˚ for Cu1 and Cu2 of 4b
(Table 6). In both compounds, the complexes are connected by N-
H···Cl hydrogen bonds and analogous to 2 the interaction propa-
gates in one direction. The main difference between compounds 4a
and 4b is the steric arrangement of complexes within hydrogen-
bonded chains. In 4a the Mn(II) atoms are placed above and under
the line constructed through Cu(II) atoms approximately in b direc-
tion, whereas in 4b the metal atoms are relatively in one line in b
direction. In 4a one chlorido ligand acts as an acceptor in two hy-
drogen bonds, one intramolecular and the second one intermolec-
ular, in 4b the situation is analogous to 2 and two chlorido ligands
participate in hydrogen bonding (Table 7). The shortest Cu-Cl dis-
˚
placed 0.1046(3) A above the plane defined by four nitrogen atoms
(
Table 4). In the crystal structure, both hydrogen atoms on nitrogen
atoms participate in N-H···Cl hydrogen bonds, one of them being
intramolecular and the second one connecting the nearest com-
plex molecule. Thus, the connection between complex molecules
propagates in c direction, the Cu-Cl distance between complexes
˚
in this direction is 3.5959(1) A. Schematic representation of hydro-
gen bonds in 2 is shown in Fig. 5, and geometrical parameters can
be found in Table 5.
[
Cu(dac)MnCl ] (4a) and [Cu(dac)MnCl ] (4b)
4
4
The structure of both complexes contains the same complex
molecule, analogous to 2 with dac ligand instead of dpc. In 4a there
is one crystallographically independent complex (Fig. 6) while 4b
contains two independent complex molecules (Fig. 7). The steric
arrangement of chlorido ligands in Mn(II) coordination environ-
ment is close to tetrahedral in all cases, with an average Mn-Cl
tance between complexes in 4a has similar values as in the case of
2, Cu1-Cl2 is 3.5271(9) A˚ , while in 4b the corresponding distances
are longer, Cu1-Cl5 is 3.8077(13) A˚ and Cu2-Cl2 3.8945(13) A˚ .
3
.3. Magnetic properties
˚
˚
bond distance 2.37(2) A for 4a, 2.366(12) and 2.364(13) A for Mn1
and Mn2 of 4b. The main deviation of tetrahedral symmetry is rep-
resented by the angle Cl4-Mn1-Cl1 of 103.84(3)° in 4a, and an-
gles Cl2-Mn1-Cl1 of 113.91(4)° and Cl6-Mn2-Cl5 of 113.06(4)° in
Our aim to synthesize ferrimagnetic systems with interesting
behavior of magnetocaloric effect at elevated magnetic fields at
low temperatures predicted by theory [12] led us to the detailed
study of magnetic properties of 2 and 4a. As the structure of both
Fig. 8. Hydrogen bonds in the crystal structure of 4a. i: 3/2-x, y-1/2, 1/2-z.
7

E. Samoľová, J. Kuchár, E. Cˇ ižmár et al.
Journal of Molecular Structure 1241 (2021) 130592
Fig. 9. Hydrogen bonds in the crystal structure of 4b. ii: x, y-1, z.
compounds is formed by heteronuclear covalent dimeric units,
the presence of AFM interaction could also suggest a possibil-
ity to study the quantum entanglement effects [40]. The room–
temperature value of the effective magnetic moment of 2 and 4a,
crease of χT due to the FM intradimer interaction is suppressed)
and to the presence of the LRO.
To confirm the presence of FM intradimer exchange interac-
tion, the BS DFT calculations were performed using the X-ray-
determined structural parameters of the molecule of 2 and 4a to
estimate the exchange interaction within the Cu(II)-Mn(II) dimers.
The calculations employing PBE0 DFT functional yielded an FM ex-
change interaction JBS/kB = 1.14 K and JBS/kB = 1.07 K for com-
pounds 2 and 4a, respectively.
μeff = 6.23 μ (μB is Bohr magneton), is very close to the ex-
B
9
pected value μ = 6.2 μ when Cu(II) (3d , spin S = 1/2) and
eff
B
Cu
5
Mn(II) (3d , spin S
= 5/2) ions are present in the molecular unit
Mn
in the paramagnetic limit (calculated using typical average values
of g-factor 2.15 and 2.0 for Cu(II) and Mn(II) ions, respectively).
While the temperature dependence of χT product of compound
The experimental results were then analyzed using a model of
4
a in Fig. 10 displays an increase below 50 K down to 10 K, the
the interacting SCu-SMn FM dimers using a spin Hamiltonian in
ˆ
χT product of compound 2 shown in Fig. 11 is almost constant
above 10 K. A sudden decrease of χT was observed below 10 K
for both compounds. An indication of long-range magnetic order
the form H = −JSˆ
S
Cu Mn
with the intradimer exchange interaction J
(J = 2JBS) and including interdimer interaction zJ’ in the mean-field
approximation [40], where z is the number of nearest neighbors. A
weak zero-field splitting typical for Mn(II) ions was neglected in
the model. The fit was performed using a custom-made code in-
(
LRO) was observed below 3.2 K in 2 as a difference between zero-
field cooled (ZFC) and field cooled (FC) magnetic response (inset of
Fig. 11).
Compounds 2,4a, and 4b, may be regarded as chain-like spin
systems (Figs. 5, 8, and 9) with the possibility to form interest-
ing ferrimagnetic chains, in this case with alternating exchange in-
teraction due to the alternation of covalent and hydrogen bonds
between Cu(II) and Mn(II) ions in the chain. The susceptibility of
ferrimagnetic chains (also with alternating bonds) is characterized
by a decrease of χT with the decreasing temperature reaching a
minimum followed by an increase of χT in the thermodynamic
limit [41]. However, the magnetic properties of studied compounds
cannot be described by such a model even when interchain inter-
action is included in the mean-field approximation [42]. Another
model was proposed accounting for an FM exchange interaction in
dimeric Cu(II)-Mn(II) units, which are effectively coupled by AFM
exchange interactions. An increase of χT of 4a below 50 K is a
clear indication of dominant FM exchange interaction and the in-
fluence of AFM exchange between dimers at low temperatures de-
creases slightly the value of χT. On the other hand, the influence
of the AFM exchange interaction in 2 is much more pronounced
yielding a significant decrease of χT at low temperature (an in-
Fig. 10. Temperature dependence of the χT product of 4a measured in ZFC regime
(circles) and the fit of the interacting dimers model (solid line) with J/kB = 2.34 K,
zJ’/kB = –0.042 K, gCu = 2.10 and gMn = 2.01.
8

E. Samoľová, J. Kuchár, E. Cˇ ižmár et al.
Journal of Molecular Structure 1241 (2021) 130592
present, and thus the formation of a 1D system is observed instead
of 3D as published elsewhere (Samoľová, private commns).
The magnetic properties of compounds 2 and 4a are governed
by the presence of an FM exchange interaction in bimetallic Cu(II)-
Mn(II) units, which was confirmed by single-point BS DFT calcula-
tions.
Supplementary data
CCDC 2038711, 2038712, 2038713, 2038714 and 2038715 con-
tain the supplementary crystallographic data for 1,3,2,4a and 4b,
respectively. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ,
UK; fax: +44 1223 336033).
Fig. 11. Temperature dependence of the χT product of 2 measured in ZFC regime
(
circles) and the fit of the interacting dimers model (solid line) with J/kB = 2.28 K,
Declaration of Competing Interest
zJ’/kB = –0.065 K, gCu = 2.09, and gMn = 2.01. Inset: Temperature dependence of
the susceptibility of 2 measured in ZFC (open circles) and FC (full circles).
All of the authors have actively contributed to the experimental
work, evaluation of the experimental results and preparation of the
maniscript. The authors have no conflicts of interest to declare. All
authors have read the manuscript and approve its submission.
cluding the simulation package EasySpin [43]. The resulting values
were J/kB = 2.28 K, zJ’/k = -0.065 K, g = 2.09, and g
= 2.01
= 2.01
B
Cu
Mn
Mn
and J/kB = 2.34 K, zJ’/k = -0.042 K, g = 2.10 and g
B
Cu
for 2 and 4a, respectively. This result confirms a sensitivity of the
magnetic response on a subtle change of the interdimer interaction
and very good agreement of the BS DFT calculations of intradimer
exchange interaction with the experiment.
CRediT authorship contribution statement
Erika Samoľová: Investigation, Writing - original draft, Writing
-
review & editing. Juraj Kuchár: Conceptualization, Formal anal-
ysis, Resources, Supervision, Visualization, Writing - original draft,
ˇ
Writing – review & editing. Erik Cižmár: Investigation, Visualiza-
4
. Conclusion
tion, Writing - original draft, Writing – review & editing. Michal
Dušek: Data curtion, Formal analysis.
Two organic ligands dpc and dac were prepared according to
the synthetic procedure described by Royal et al. [14]. This pro-
cedure is strongly selective for the preparation of 1,8-trans disub-
stitued cyclams, runs at mild conditions, and leads to relatively
high yields. We observed a lower yield in the case of prepara-
tion of dpc; therefore we lengthened the reaction time in the
step of 1,8-Dipropyl-4,11-diazoniatricyclo[9.3.1.14,8]hexadecane di-
bromide preparation. Using prepared ligands dac and dpc, Cu(II)
complexes 1 and 3 with the analogous structure were prepared
and consequently used for the synthesis of bimetallic complexes
using the complex as ligand strategy, which should lead to the
preparation of coordination compounds with predictable dimen-
sionality. Thus, heterobimetallic compounds 2,4a, and 4b were
Acknowledgments
The financial support for this work was given by the Slo-
vak Research and Development Agency (APVV-18-0197 and APVV-
18-0016) and the Scientific Grant Agency of Ministry of Educa-
tion, Science, Research and Sport of the Slovak Republic (VEGA
1/0063/17, VEGA 1/0426/19) is acknowledged. CzechNanoLab
project LM2018110 funded by MEYS CR is gratefullyacknowledged
for the financial support of the measurements/samplefabrication
at LNSM Research Infrastructure. This publication is the result of
the project implementation: New unconventional magnetic ma-
terials for applications, ITMS 313011T544, supported by the Op-
erational Programme Integrated Infrastructure 2014 - 2020 (OPII)
funded by the ERDF. The authors are very grateful to Assoc. Prof.
Ivan Poto cˇ nˇ ák, PhD. for measuring elemental analysis. E.S. thanks
to the research group of Coordination and Bioinorganic Chemistry
at Charles University in Prague for the opportunity to work in their
laboratory.
prepared with analogous {Cu(L)MnCl } structure motif in each
4
case. According to our knowledge, -Cu-Cl-Mn- structure motif in
bimetallic complexes is rare. In the case of chain compound, it was
observed previously only by Cu(en) MnCl , published by Chiari
2
4
et al. [30], but similar systems based on cyclam or its derivatives
and MnCl4 have not been registered in CCDC yet.
Bond distances characterizing coordination polyhedrons of
Mn(II) and equatorial plane of Cu(II) are consistent with bond dis-
tances in already known complexes with analogous structure mo-
tif [30] as well as with complexes with ethane-1,2-diamine deriva-
tives prepared by our research group. The difference occurs in the
case of the Cu(II) coordination environment. In the case of ethane-
Supplementary materials
Supplementary material associated with this article can be
found, in the online version, at doi:10.1016/j.molstruc.2021.130592.
1,2-diamine and its derivatives Cu(II) has tetragonal bipyramidal
polyhedron and both axial distances have values near to the sum
of VdW radii (2.804 and 3.063 in Chiari et al. [30]; 2.8714(15),
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