Two new Cu(II) and Ni(II) 1,10-phenanthroline complexes with anions of barbituric acids in the outer sphere: Synthesis, structure, spectroscopic, magnetic and thermal properties

Article abstract of DOI:10.1016/j.molstruc.2020.128526

Two new complexes [Cu(Phen)₂(H₂O)](Hba)₂?3H₂O (1) and [Ni(Phen)₃](Htba)₂]?Phen?2H₂O (2) (Phen = 1,10-phenanthroline, Hba^? = barbiturate ion, Htba^? = thiobarbiturate ion) have been synthesized and characterized by elemental analysis, single-crystal and powder XRD, magnetic measurements, TG-DSC, FT-IR, and Vis absorption spectra. Complex 1 shows a distorted square pyramidal geometry around the copper (II) metal center. The coordination around the Ni atom is a distorted octahedron NiN₆. The 3D and 2D supramolecular structures of 1 and 2 are formed respectively by intermolecular H-bonds. Two N–H?O hydrogen bonds in 1, and N–H?O, N–H?S hydrogen bonds in 2 form infinite chains. As a result of π–π interactions, similar 4-membered zigzag chains in structures 1 and 2 respectively are formed.

Full text of DOI:10.1016/j.molstruc.2020.128526

Journal of Molecular Structure 1219 (2020) 128526
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: http://www.elsevier.com/locate/molstruc
Two new Cu(II) and Ni(II) 1,10-phenanthroline complexes with anions
of barbituric acids in the outer sphere: Synthesis, structure,
spectroscopic, magnetic and thermal properties
, a, c,
Nicolay N. Golovnev a, Maxim S. Molokeev b
*, Irina V. Sterkhova d,
Maxim K. Lesnikov a, Anastasia V. Demina a, Gennady S. Patrin e
a Siberian Federal University, 79 Svobodny Ave., Krasnoyarsk, 660041, Russia
,
a
b Laboratory of Crystal Physics, Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Bld. 38 Akademgorodok 50, Krasnoyarsk, 660036, Russia
c Department of Physics, Far Eastern State Transport University, 47 Seryshev Str., Khabarovsk, 680021, Russia
d Favorsky Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1 Favorsky, Irkutsk, 664033, Russia
e Laboratory of Magnetic Dynamics, Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Bld. 38 Akademgorodok 50, Krasnoyarsk, 660036,
Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
Two new complexes [Cu(Phen)2(H2O)](Hba)2∙3H2O (1) and [Ni(Phen)3](Htba)2]∙Phen∙2H2O (2)
(Phen ¼ 1,10-phenanthroline, Hbaꢀ ¼ barbiturate ion, Htbaꢀ ¼ thiobarbiturate ion) have been synthe-
sized and characterized by elemental analysis, single-crystal and powder XRD, magnetic measurements,
TG-DSC, FT-IR, and Vis absorption spectra. Complex 1 shows a distorted square pyramidal geometry
around the copper (II) metal center. The coordination around the Ni atom is a distorted octahedron NiN6.
The 3D and 2D supramolecular structures of 1 and 2 are formed respectively by intermolecular H-bonds.
Two NeH/O hydrogen bonds in 1, and NeH/O, NeH/S hydrogen bonds in 2 form infinite chains. As a
Received 17 January 2020
Received in revised form
11 May 2020
Accepted 25 May 2020
Available online 6 June 2020
Keywords:
Barbituric acids
Phenanthroline complexes
X-ray diffraction
result of
formed.
pe
p
interactions, similar 4-membered zigzag chains in structures 1 and 2 respectively are
© 2020 Elsevier B.V. All rights reserved.
Thermal
Spectroscopic and magnetic properties
1. Introduction
for molecular recognition and crystal design [7e10]. Design stra-
tegies simultaneously employing coordination bonds, hydrogen
Transition metal сomplexes containing phenanthroline (Phen)
have been interesting for their applicability in catalysis [1], me-
dicinal chemistry [2], photoelectronic and magnetic materials [3].
Attached to metal ions, the Phen ligands favor the intermolecular
bonds, and
pep stacking interactions in crystal engineering are
mostly not well documented so far [11]. The often so-called
pep
interactions are in the order of 10 kcal molꢀ1, thus further stabi-
lizing the structural arrangement [12]. Within a systematic study of
the metal barbiturate complexes, two mixed-ligand complexes,
[Cu(Phen)2(H2O)](Hba)2∙3H2O (1) and [Ni(Phen)3](Htba)2∙-
Phen∙2H2O (2), were prepared and studied. The main objective of
this work is to compare the crystal structure of the synthesized
complexes based on the analysis of supramolecular interactions
pep stacking interactions with other aromatic molecules or ions,
such as barbituric acids [4], which can play an important role in
sustaining supramolecular solid-state architectures [5]. Barbituric
(H2ba) and 2-thiobarbituric (H2tba) acids (Fig. 1S) are the parent
molecules of 5,5-substituted barbiturates and thiobarbiturates,
which are important groups of sedative/hypnotic drugs [6]. The
Hbae and Htbae anions possess good hydrogen-bonding acceptors
(hydrogen bonds,
pep
interactions) of uncoordinated Hbae and
Htbae ions with 1,10-phenanthroline.
and donors, and are prone to pep interactions, which is important
2. Experimental section
* Corresponding author. Laboratory of Crystal Physics, Kirensky Institute of
Physics, Federal Research Center KSC SB RAS, bld. 38 Akademgorodok 50, Kras-
noyarsk, 660036, Russia.
2.1. Reagents and synthesis
E-mail address: msmolokeev@gmail.com (M.S. Molokeev).
1,10-phenanthroline monohydrate (CAS number: 5144-89-8),
https://doi.org/10.1016/j.molstruc.2020.128526
0022-2860/© 2020 Elsevier B.V. All rights reserved.

2
N.N. Golovnev et al. / Journal of Molecular Structure 1219 (2020) 128526
2.1.1. Synthesis of crystal 1
0.10 g (0.78 mmol) of barbituric acid in 5 ml of water was
neutralized with an equimolar amount of solid NaOH (0.031 g,
0.78 mmol) at 90 ꢁC for 5 min. To the resulting hot solution, 0.066 g
of CuCl2$2H2O (0.39 mmol) and 0.155 g (0.78 mmol) of 1,10-
phenanthroline monohydrate were added in turn with stirring.
The produced bulk green precipitate dissolved after the copper salt
was added to the reaction mixture, and the solution color changed
from green to dark green. The resulting solution (~4 ml) was slowly
cooled and allowed to evaporate at room temperature (pH 5). A day
later, the dark green rectangular crystals were observed, which
were filtered off and dried in air to a constant weight (yield: 63%). A
single crystal for the X-ray diffraction analysis was taken directly
from the total mass of the product. The elemental analysis for
C32H30CuN8O10 (1): Calc.: C, 51.2%; H, 4.03%; N, 14.9%. Found: C,
50.8%; H, 4.21%; N, 14.6%. Complex 1 is soluble in water, alcohol,
acetone and dimethyl sulfoxide.
2.1.2. Synthesis of crystal 2
To 2-thiobarbituric acid (0.1 g, 0.69 mmol) in 10 ml of water, a 5%
excess of nickel carbonate (0.050 g, 3 mmol) was added, then the
mixture was kept at 90 ꢁC for 1 h and unreacted nickel carbonate
was filtered off. To the hot green filtrate (6 ml), 1,10-phenanthroline
monohydrate (0.206 g, 1.0 mmol) was added with stirring. The
resulting mixture, consisting of a heavier red oil and an orange
solution on top (pH 6), was slowly cooled and left at room tem-
perature for 3 days. The formed stick-shaped red crystals of 2 were
filtered and dried in the air to a constant weight (yield: 73%). A
single crystal for X-ray diffraction analysis was taken directly from
the crystalline precipitate. The elemental analysis for
C56H40N12NiO6S2 (2): Calc.: C, 61.2%; H, 3.67%; N, 15.3%, S, 5.83%.
Found: C, 60.7%; H, 3.88%; N, 14.9%; S, 5.67%. Complex 2 is soluble in
dimethyl sulfoxide, alcohol, acetone and water.
2.2. X-ray diffraction analysis
The intensity patterns were collected from single crystals 1 and
2 at 293 K using D8 Venture diffractometer (Bruker AXS) equipped
with a CCD-detector, graphite monochromator and Mo Ka radiation
source. The absorption corrections were applied using the SADABS
program. The structures were solved by the direct methods using
the SHELXS package and refined in the anisotropic approach for
non-hydrogen atoms using the SHELXL program [13]. All hydrogen
atoms in 1 and almost all in 2 were found with the Fourier differ-
ence maps. Hydrogen atoms of one disordered water molecule
were not localized in structure 2. Further, the hydrogen atoms
which are linked with C,N atoms in the 1 and 2 were positioned
geometrically as riding on their parent atoms with
d (CeH) ¼ 0.93e0.98 Å, d (NeH) ¼ 0.89 Å depending on geometry
and Uiso(H) ¼ 1.2Ueq (C,N). The structure test for the presence of
missing symmetry elements and possible voids was carried out
with the PLATON program [14]. For the crystal structure plotting,
the DIAMOND software [15] was used.
Fig. 1. The asymmetric unit of the [Cu(Phen)2(H2O)](Hba)2∙3H2O (1) (a),
[Ni(Phen)3](Htba)2∙Phen∙2H2O (2) (b) unit cell. Independent molecules are marked by
labels (AeD). The intermolecular hydrogen bonds in 1 and 2 are represented by dashed
lines. The ellipsoids are drawn at the 50% probability level, except for the hydrogen
atoms represented by spheres.
The powder X-ray diffraction data of 1 and 2 were obtained
using the D8 ADVANCE diffractometer ((Bruker, analytical equip-
ment of the Center for Сollective Use of KSC SB RAS) equipped with
a VANTEC detector with a Ni filter. The measurements were made
barbituric acid (CAS number: 67-52-7) and 2-thiobarbituric acid
(CAS number: 504-17-6) were commercially available from Sigma-
Aldrich. CuCl2$2H2O, NiCO3, NaOH, acetone, ethyl alcohol and
dimethyl sulfoxide were obtained as reagents of analytical grade
(Acros) and they were also used without additional purification.
using Cu Ka radiation. The structural parameters defined by single
crystal analysis were used as a baseline in powder pattern Rietveld
refinement. The refinement was carried out with the TOPAS pro-
gram [16]. Low R-factors and good refinement results shown in
(Fig. 2S) indicate the crystal structures of the powder samples to be
representative one of the 1 and 2 bulk structure.

N.N. Golovnev et al. / Journal of Molecular Structure 1219 (2020) 128526
3
2.3. Physical measurements
min. The qualitative composition of the evolved gases was deter-
mined by the Nicolet380 FT-IR spectrometer (Thermo Scientific,
USA) combined with a thermal analyzer and the TGA/FT-IR inter-
face (gas phase analysis attachment). This set up allows simulta-
neous accumulation of the DTA/TG data and the released gas
TGA was carried out on the simultaneous SDT-Q600 thermal
analyzer (TA Instruments, USA) under the dynamic air atmosphere
(50 ml/min flow rate) within 25e800 ꢁC at the scan rate of 10 ꢁC/
Fig. 2. Hydrogen bonding in 1 (a) and 2 (b). The H-bonds are marked by dashed lines, the H-bond motifs are marked by circles.

4
N.N. Golovnev et al. / Journal of Molecular Structure 1219 (2020) 128526
composition. The compound weight was 7.044 mg for 1 and
6.930 mg for 2. Platinum crucibles with perforated lids were used
as containers. The IR spectra were recorded as KBr pellets on the
Nicolet 6700 FT-IR spectrometer (Thermo Scientific, USA, SFU CEJU,
School of Petroleum and Gas Engineering) in the of
400e4000 cmꢀ1 region. UVeVis spectra were recorded on the
Evolution 300 spectrophotometer (Thermo Scientific, UK). Mag-
netic measurements were performed on the MPMS-XL SQUID
magnetometer in magnetic fields up to 50 kOe at temperatures of 5,
15 and 50 K. The chemical analysis was carried out with the HCNS-
0 EA 1112 Flash Elemental Analyser.
with the most distant from the metal nitrogen atom N2A in the
apical position and distorted trigonal bipyramidal, where two
proximate nitrogen atoms N1A and N2B. The distortion degree is
indicated by the general descriptor
coordinated complexes, where and
at the metal center. If ranges from 0 to 0.5, the molecular ge-
ometry is distorted square pyramidal, while the value of between
0.5 and 1 indicates that the molecular geometry is distorted
trigonal bipyramidal [21e23]. In complex 1, is 0.41; therefore, the
t
¼ (
b e a)/60 for the five-
a
b are the two largest angles
t
t
t
five-coordinated Cu(II) ion shows a distortion of the square pyra-
midal geometry. The axial position is occupied by the N2A atom of
coordinated Phen molecule, d (CueN2A) ¼ 2.183(2) Å. The axial
CueN distance is quite longer than the equatorial ones (1.996(3),
2.015(2) and 2.017(2) Å). The elongation of the apical bond length in
complex 1 is of comparable magnitude to that observed in the
previously reported square pyramidal complexes [5,18]. The
N2BeCueN1A angle is 176.64(10)ꢁ. The angles around the copper
(II) atom in the basal plane vary from 101.71(7)ꢁ to 152.17(8)ꢁ,
which indicates a strongly distorted geometry. The dihedral angle
between the chelate Phen ligands is 69.46(7)ꢁ. The barbiturate
anions are located in the outer-sphere. The main CeO, CeN, CeC
bond lengths (Table 1S) and the angles in them coincide with
those found earlier in other related compounds containing unco-
ordinated Hbae ions [24e27]. Crystallization water fills the voids
between the [Cu(Phen)2(H2O)]2þ cations.
There are four NeH/O and eight OeH/O hydrogen bonds in
the structure 1 (Table 2S) which form a 3D network. All hydrogen
atoms of all water molecules are involved in hydrogen bonding.
This is a 4-nodal net with stoichiometry (3-c) (4-c) (5-c) (6-c) and
with vertex symbol (3.42) (3.43.5.6.73.82.92.102) (32.4.52.6)
(32.42.52.6.73) which is unknown in the ToposPro database [28]. The
2D layer in the plane based on aeb and c axis with supramolecular
motifs R22(8), R54(16) and R67(22) can be marked (Fig. 2a). NeH/O
3. Results and discussion
3.1. Crystal structure of 1
Complex [Cu(Phen)2(H2O)](Hba)2∙3H2O (1) crystallizes in a
monoclinic system and its structure is solved in the space group Cc.
The crystal structure of
1
consists of
a
mononuclear
[Cu(Phen)2(H2O)]2þ cation and two barbiturate counter anions and
three crystallization water molecules. The main crystal data are
shown in Table 1. The main detected bond lengths are shown in
Table 1S.
The asymmetric unit cell contains one Cu2þ ion, two Phen
molecules, two Hbae ions and four H2O molecules (Fig. 1a). The
Cu2þ ion is coordinated by one H2O molecule and two Phen mol-
ecules through four
N
atoms. The bond lengths are
d (CueN) ¼ 1.996(3)e2.183(2) Å and d (CueOw) ¼ 1.958(2) Å,
which are close to the corresponding distances in other compounds
containing the [Cu(Phen)2(H2O)]þ cation [3,5,17e20]. The
N1AeCueN2A and N1BeCueN2B bond angles are 79.66(8)ꢁ and
81.92(9)ꢁ. In this structure, N4O surrounding the metal may be
described as intermediate between distorted square pyramidal
Table 1
Crystal structure parameters of 1 and 2.
Single crystal
[Cu(Phen)2(H2O)](Hba)2∙3H2O
[Ni(Phen)3](Htba)2∙Phen∙2H2O
Moiety formula
Dimension (mm)
Color
C32H30CuN8O10
0.48 ꢂ 0.25 ꢂ 0.12
green
C56H40N12NiO6S2
0.50 ꢂ 0.40 ꢂ 0.15
red
Molecular weight
Temperature (K)
Space group, Z
a (Å)
b (Å)
c (Å)
750.18
293
Cc, 4
1099.83
293
P21/n, 4
17.1196 (4)
12.2262 (3)
14.9531 (4)
90
92.989 (1)
90
3125.54 (13)
1.594
0.774
13.5359 (5)
21.3738 (8)
17.8164 (6)
90
103.023 (1)
90
5022.0 (3)
1.455
0.536
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
V (Å3)
rcalc (g/cm3)
m
(mmꢀ1
)
Reflections measured
35454
189270
Reflections independent
8882
14721
Reflections with F > 4
2
s
(F)
8533
60.14
11287
60.14
qmax (ꢁ)
h, k, l - limits
ꢀ24 ꢃ h ꢃ 24;
ꢀ17 ꢃ k ꢃ 17;
ꢀ21 ꢃ l ꢃ 20
0.0306
ꢀ18 ꢃ h ꢃ 19;
ꢀ30 ꢃ k ꢃ 30;
ꢀ25 ꢃ l ꢃ 24
0.0633
Rint
The weighed refinement of F2
w ¼ 1/[
s
2(F2o)þ(0.0434P)2þ0.8913P], P ¼ (Fo2þ2F2c)/3
w ¼ 1/[
s
2(F2o)þ(0.0721P)2þ8.74P], P ¼ (Fo2þ2F2c)/3
Number of refinement parameters
485
700
R1 [Fo > 4
wR2
s
(Fo)]
0.0266
0.0679
1.024
0.0555
0.1376
1.015
Goof
Drmax (e/Å3)
0.321
3.028
Drmin (e/Å3)
ꢀ0.666
ꢀ2.245
(D/s)
max
0.000
0.000

N.N. Golovnev et al. / Journal of Molecular Structure 1219 (2020) 128526
5
Table 2
monoclinic system and the structure is solved in the space group
P21/n. The crystal structure of 2 consists of a mononuclear
[Ni(Phen)3]2þ cation, two thiobarbiturate counter anions, uncoor-
dinated Phen and two water molecules. Details of the data collec-
tion and the parameters of the refinement process are presented in
Table 1. Selected bond lengths are listed in Table 1S.
The magnetizations and the number of magnetic particles.
Magnetic ion
M (erg/Oe)
N (un./g)
N (un./cm3)
Cu2þ
Ni2þ
2.104ꢄ10ꢀ20
6.164ꢄ1020
3.867ꢄ1020
3.150ꢄ10ꢀ20
4.09ꢄ1020
2.81ꢄ1020
The asymmetric unit contains one Ni2þ ion, four Phen mole-
cules, two Htbae ions and two H2O molecules (Fig. 1b). One of the
two water molecules is disordered over two positions. The Ni2þ ion
is coordinated by three Phen molecules through six N atoms,
forming NiN6 octahedron with d (NieN) ¼ 2.076(2)e2.124(2) Å
which is also falls into the interval obtained for other pre-
characterized compounds containing [Ni(Phen)3]2þ cation [30].
These values are slightly bigger than d (NieN) 2.054(2)e2.055(2) Å,
hydrogen bonds form the infinite chains of Hbaealong axis a based
on the R22(8) pattern. These chains are linked by OweH$$$O
hydrogen bonds. Coordinated Phen molecules are not involved in
H-bonding. In addition, there are the pep interactions between the
rings of Phen molecules and Hbae ions (Fig. 3a, Table 3S) that form
discrete units. The interplanar separation of Phen ligands (A, B) in
the centrosymmetric pattern with overlapping phenylꢀphenyl
rings is 3.3833(10) Å, and centroid$$$centroid distance is
3.5309(14) Å thus indicating the slipping stacking interaction with
offset. Moreover, each phenanthroline molecule is bound by phe-
acquired earlier for [Ni(Phen)(H2O)3Br]Br compound [27].
A
possible reason for the greater distance d (NieN) in 2 is the greater
mutual repulsion between the three coordinated Phen ligands. The
dihedral angle between the chelate ligands A and B, A and C, B and C
are 66.40(8), 72.53(5), 80.70(8)ꢁ respectively. Water molecules are
mainly located between the layer shown in Fig. 2b and the layer of
[Ni(Phen)3]2þ cations. Complex 2, as well as 1 has a discrete
structure. One of the four 1,10-phenanthroline molecules in 2 does
nyl(Phen)ꢀHbae
pep interaction with one barbiturate ion forming a
zigzag HbaeꢀPhenꢀPhenꢀHbae chain. The interplanar separations
of Phen and Hbae in the pattern with overlapping phenyl rings are
3.2886(10), 3.4905(13) Å, and centroid$$$centroid distances are
3.4905(13), 3.6019(13) Å. It should be noted that the same 4-
membered HbaeꢀPhenꢀPhenꢀHbae chains are also formed in
the structure [Co(Phen)2(H2O)2](Hba)2∙2H2O [27]. Similar chains of
HbaeꢀBipyꢀBipyꢀHbae (Bipy ¼ 2,20-bipyridine) are also found in
the complexes [Cu2(Bipy)2(H2O)2(OH)2](Hba)2$2H2O and [Cu(Bipy)
(H2O) (Hba)Cl]$2H2O [29].
not form
a
chemical bond with nickel ions. Htbae anions
compensating the [Ni(Phen)3]2þ cation charge, like one of the 1,10-
phenanthroline molecule, are located in the outer sphere. As in 1,
the main CeO, CeN, CeC bond lengths (Table 1S) and the angles in
barbiturate ions coincide with those found in other complexes
containing uncoordinated Htbae ions [26,31,32].
There are three NeH/O, one NeH/S and two OeH/O
hydrogen bonds in the structure (Fig. 2b, Table 2S) forming a 2D
network. Htbae anions form infinite chains of Hbae along axis b
3.2. Crystal structure of 2
Complex [Ni(Phen)3]Phen(Htba)2∙2H2O (2) crystallizes in a
Fig. 3.
pep interactions in 1 (a) and 2 (b). Some hydrogen atoms in figure (b) were omitted for the picture clarity.

6
N.N. Golovnev et al. / Journal of Molecular Structure 1219 (2020) 128526
based on the R22 (8) pattern. These chains are interconnected by
pairs OweH$$$O hydrogen bonds. Since the hydrogen atoms of
disordered H2O molecule were not localized, some hydrogen bonds
were missed. Anyway, the present hydrogen 2D net was analyzed.
This net is an uninodal 3-c net with vertex symbol (4.82) known as
range 550e800 nm centered at ca. 730 nm for 1 and a broad band in
the range 460e580 nm centered at ca. 520 nm for 2, which are
consistent with the presence of the Cu(II) chromophore with dis-
torted square-pyramidal geometry and Ni(II) chromophore with
octahedral geometry [38]. The broad band at lmax ¼ 740 nm in
DMSO and 730 nm in water is assigned to 2Eg/2T2g transition of
Cu(II) (d9). The response band at lmax ¼ 452 nm in DMSO and
520 nm in water is assigned to ded* transition of Ni(II) ion (d8)
[3A2g/3T1g(P)] [38,39].
fes net in the ToposPro database [28]. Moreover, there are
interactions between the rings of Phen molecules and Hbae ions.
There are interactions between the rings of B phenanthroline
molecules coordinated to different nickel ions and Hbae ions in 2
pep
pep
(Fig.
3b,
Table
3S)
forming
4-member
chains
HtbaeꢀPhenꢀPhenꢀHtbae. A similar interaction pattern is also
3.4. Magnetic properties
established in complex 1. As [Cu(Phen)2(H2O)]2þ cations in 1, the
[Ni(Phen)3]2þ cations are united into pairs by
p
ꢀp
interaction be-
The results of magnetization (M) measurements of the copper-
containing (part 1) and nickel-containing (part 2) polycrystals
(experimental points) are shown in Fig. 8S. The temperature de-
pendences of the magnetization for both magnetic ions (part a) are
qualitatively similar, and give reason to consider them as para-
magnets. The field dependences of the magnetization for com-
plexes 1 and 2 (part b) also have a similar nature. The experimental
magnetization dependences were fitted by the Langevin function
[40].
tween the neighboring Phen of a head-to-tail type (Fig. 3b). The
interplanar separation of Phen ligands B in the centrosymmetric
pattern with overlapping of phenylꢀphenyl rings is 3.4188(9) Å,
and centroid$$$centroid distance is 3.6155(13) Å thus indicating the
slipping stacking interaction with offset. In addition, each phe-
nanthroline molecule is bound by phenyl(Phen)ꢀHtbae
pep inter-
action with one barbiturate ion. The interplanar separation of Phen
(B) and Htbae (F) in the pattern with overlapping of phenyl rings is
3.8892(9) Å, and centroid$$$centroid distance is 3.9724(14) Å. Un-
coordinated D phenanthroline molecule is also involved in
pe
p
M ¼ Nm[coth(mH/KBT) ꢀ (KBT/mH)],
interactions with the coordinated C phenanthroline molecule. The
interaction involves one phenyl and one pyridine ring of each Phen
molecule. The interplanar separations of these Phen molecules in
the pattern with overlapping of phenylꢀpyridine rings are
3.5469(10) and 3.7595(10) Å, and centroid$$$centroid distances are
3.7637(14), 3.9327(15) Å. In addition to complex 2, only two
structurally characterized complexes contain simultaneously co-
ordinated and uncoordinated phenanthroline molecules [30]. In
where N is the number of magnetic particles per mass and volume
unit, m is the magnetic moment of the particle, KB is the Boltzmann
constant, T and H are temperature and magnetic field strength,
respectively. Table 2 shows the values of the magnetic moment and
the number of magnetic particles in 1e2.
3.5. Thermal decomposition
{Ni(Phen)3}2[V14Sb8O42]$Phen$12H2O [33]
pep interactions be-
tween the [Ni(Phen)3]2þ cations form an infinite chain (Fig. 3S). The
cationic layer in {Ni(Phen)3}2[V4O12]∙Phen∙22H2O [34] is also
Thermal decomposition of complexes 1 and 2 started with the
release of water molecules, which was confirmed by the IR spec-
troscopic analysis of released gases. In 1, an experimental weight
stabilized by pep interactions between phenanthroline molecules,
both coordinated to the central atom and uncoordinated solvate
molecules.
loss (D
m) of 10.0% is observed between 75 and 175 ꢁC (Fig. 9S),
which corresponds to the release of the coordinated and crystalli-
zation water molecules (e4H2O,
D
mtheor ¼ 9.61%). At T > 250 ꢁC, the
3.3. Spectroscopic study
oxidative decomposition of [Cu(Phen)2(H2O)](Hba)2∙3H2O (1)
most likely begins, accompanied by the strong exothermic effect at
509.7 ꢁC. At 650 ꢁC, the final product consists mainly of copper (II)
The IR spectra of the complexes (Figs. 4Se5S) were analyzed
using data from Ref. [25,26,35e37]. They are significantly different
from the spectra of starting reagents, thereby indicating the for-
mation of new compounds. In the IR spectrum of 1 (Fig. 4S, curve 3),
the broad bands centered at 3530 and 3383 cmꢀ1 are assigned to
oxide CuO (Fig. 10S). The total
Dm was found to be 90.1%, which is
bigger than that calculated for the transformation of 1 to CuO
(
D
mtheor ¼ 89.4%), the difference may be due to the impurities in
the analyzed sample and the thermolysis product. The DSC and TG
curves of [Ni(Phen)3](Htba)2∙Phen∙2H2O (2) show two-step
dehydration (Fig. 11S) which is accompanied by an endo effect at
141.3 ꢁC. The first dehydration stage proceeded in the range of
75e130 ꢁC, which corresponds to the release of the lattice water
the n(OH) stretching vibrations of coordinated and crystallization
water molecules [35], which fits the results of elemental and
thermal analyses. A broad band centered at 3086 cmꢀ1 is assigned
to the n
(NH) stretching vibrations of Hbae ions. The vibration bands
centered at 1519, 1429 and 1355 cmꢀ1 in IR spectra of 1 and 1515,
1449 and 1353 cmꢀ1 in IR spectra of 2 indicate the presence of 1,10-
phenanthroline. In the IR spectrum of complex 2 (Fig. 5S, curve 3),
molecule with
D
m ¼ 1.4% (eH2O,
D
mtheor ¼ 1.6%). The second
dehydration stage in the range of 130e150 ꢁC showed
D
m ¼ 1.5%
(eH2O,
D
mtheor ¼ 1.6%). At T > 210 ꢁC, the oxidative decomposition
the bands at 3386 and 3550 cmꢀ1 are assigned to the
n
(OH) vi-
brations of water molecules and a broad band centered at
3167 cmꢀ1 is assigned to the (NH) stretching vibrations of Htbae
of 2 is accompanied by four exothermic effects, the strongest of
which registered at 607.8 ꢁC. At 680 ꢁC, the final product consists
mainly of nickel oxide NiO (Fig. 12S). The total experimental weight
loss was found to be 94.0%, which is bigger than that calculated for
n
ions. The bands with the frequencies 1682 and 1609 cmꢀ1 in the IR
spectra 1 and 2 respectively are assigned to the stretching mode of
CO in Hbae and Htbae ions [25,26]. Peaks at 431 and 426 cmꢀ1 in
the spectra of 1 and 2 respectively are attributed to the M ꢀ N
stretching vibrations [37]. IR spectra of the complexes 1 and 2 are
well-aligned with the result obtained by single crystal X-ray
diffraction. The electronic spectra of 1 (Figs. 6S) and 2 (Fig. 7S), in
DMSO, show broad bands in the 650e800 nm and 440e490 nm
range of MLCT character, centered at 740 and 452 nm, respectively.
The ded* spectra of aqueous solutions exhibit a broad band in the
the transformation of 2 to NiO (
ference may be due to the impurities in the analyzed sample and
thermolysis product.
D
mtheor ¼ 93.2%). As in 1, the dif-
4. Conclusions
Two mixed-ligand Cu(II) and Ni(II) complexes with composi-
tions [Cu(Phen)2(H2O)](Hba)2∙3H2O (1) and [Ni(Phen)3](Htba)2∙-
Phen∙2H2O (2) were prepared and studied. In 1, the five-

N.N. Golovnev et al. / Journal of Molecular Structure 1219 (2020) 128526
7
bipyridine and phenantroline complexes: tailor-made catalysts for the se-
lective oxidation of tetralin, Appl. Catal. 360 (2009) 218e225, https://doi.org/
10.1016/j.apcata.2009.03.022.
coordinated Cu(II) ion shows a distortion of square pyramidal ge-
ometry. The coordination around the Ni atom is a distorted octa-
hedron, expected because of the presence of the rigid Phen ligand.
Non coordinating counterions Hbae and Htbae are in the outer
sphere of these complexes. The intermolecular hydrogen bonds
NeH/O, OeH/O in the structure 1 and NeH/O, OeH/O,
NeH/S in the structure 2 form a 3D and 2D network, respectively.
In structures, the Hbae and Htbae ions are connected by hydrogen
bonds in the infinite zigzag chains based on the R22(8) pattern. In
1e2, the centrosymmetric R22(8) pattern is formed by two NeH/O
hydrogen bonds. In addition, in 2, it is formed using one NeH/O
and NeH/S hydrogen bonds, with the different atomic composi-
tion patterns following each other in a chain (Fig. 2a). In 1, the
chains of Hbae ions are linked via NeH … OHba(chain 1) … HeOweH
… OHba(chain 2) interactions. In 2, the chains of Htbae are connected
by one water molecule, which is a donor of two hydrogen bonds.
Phen molecules in the complexes do not participate in hydrogen
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Molokeev: Conceptualization, Methodology, Writing - original
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Irina V. Sterkhova: Investigation, Visualization. Maxim K. Lesni-
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Supplementary data
The crystallographic data (excluding structure factors) for the
structural analysis have been deposited with Cambridge Crystal-
lographic Data Center (1 - CCDC # 1962890; 2 - CCDC # 1962891).
The information may be obtained free of charge from The Director,
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