Synthesis, characterization, crystal structure, and electrochemical property of copper(II) complexes with Schiff bases derived from 5-halogenated salicylaldehyde and amantadine

Article abstract of DOI:10.1134/S1070328417110033

A mixture of copper(II) chloride dihydrate and ligands derived from amantadine and 5-halogenated salicylaldehyde in anhydrous methanol generated two novel complexes C₃₄H₃₈Cl₂CuN₂O₂ (I) and C₃₄H₃₈Br₂CuN₂O₂ (II), respectively. The complexes were characterized by melting point, elemental analysis, molar conductance, IR, UV-Vis, and single-crystal X-ray diffraction (CIF files nos. 1435429 (I), 1435430 (II)). Single-crystal X-ray diffraction analysis reveals that both complexes crystallize in monoclinic system, P2₁/c space group. Each asymmetric unit consists of two mononuclear copper(II) complex molecules and each complex molecule includes one copper(II) atom two corresponding deprotonated ligands. The central copper(II) atom is four-coordinated via two nitrogen atoms and two oxygen atoms from the corresponding Schiff base ligands, forming a distorted tetrahedral geometry. Electrochemical properties of the complexes were studied by cyclic voltammetry.

Full text of DOI:10.1134/S1070328417110033

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2017, Vol. 43, No. 11, pp. 787–794. © Pleiades Publishing, Ltd., 2017.
Synthesis, Characterization, Crystal Structure, and Electrochemical
Property of Copper(II) Complexes with Schiff Bases Derived
1
from 5-Halogenated Salicylaldehyde and Amantadine
a,
a
a
a
a
a
X. D. Jin *, W. C. Wang , X. X. Feng , L. C. Bu , J. Tong , P. Zhang ,
b
b
K. J. Ren , and X. B. Zhao
a
College of Chemistry, Liaoning University, Shenyang, 110036 P.R. China
Liaoning Provincial Institute of Safety Science, Shenyang, 110003 P.R. China
b
*
e-mail: jinxudong@lnu.edu.cn
Received January 3, 2017
Abstract—A mixture of copper(II) chloride dihydrate and ligands derived from amantadine and 5-haloge-
nated salicylaldehyde in anhydrous methanol generated two novel complexes C H Cl CuN O (I)
3
4
38
2
2
2
and C H Br CuN O (II), respectively. The complexes were characterized by melting point, elemental
3
4
38
2
2
2
analysis, molar conductance, IR, UV-Vis, and single-crystal X-ray diffraction (CIF files nos. 1435429 (I),
435430 (II)). Single-crystal X-ray diffraction analysis reveals that both complexes crystallize in monoclinic
1
system, P2 /c space group. Each asymmetric unit consists of two mononuclear copper(II) complex molecules
1
and each complex molecule includes one copper(II) atom two corresponding deprotonated ligands. The cen-
tral copper(II) atom is four-coordinated via two nitrogen atoms and two oxygen atoms from the correspond-
ing Schiff base ligands, forming a distorted tetrahedral geometry. Electrochemical properties of the com-
plexes were studied by cyclic voltammetry.
Keywords: copper(II) complexes, amantadine, Schiff base, synthesis, crystal structure, cyclic voltammetry
DOI: 10.1134/S1070328417110033
INTRODUCTION
the ion channel, which formed by the M2 protein of
influenza A viruses [8–12]. Salicylaldehyde and its
derivatives, especially one or more halo-atoms on the
benzene ring, exhibited antibacterial and antiviral
Recent years, Schiff bases have been widely
investigated owing to their biological activity [1, 2].
Schiff bases also brought about many metal-based
pharmaceuticals for their complexation characteris- activity and were used to produce efficient herbicides,
tics [3]. Copper is one of the prevalent trace ele- insecticides and fungicides [13–16]. In view of these
ments and an important enzyme active site in points above, we designed and managed to synthesize
human body [4, 5]. Copper(II) complexes have a a series of complexes containing both copper(II) ions
wider range of coordination geometries than any
other transition metal ions [6]. Some copper(II)
complexes exhibit significantly enhanced antibacte-
rial and antifungal activity as compared to their cor-
responding Schiff base ligands [7].
and the ligands derived from amantadine and haloge-
nated salicylaldehyde. As an extension of our previous
work on metal complexes with bulky Schiff bases [17–
23], in this work, two novel four-coordinated cop-
per(II) complexes bis(2-(1-adamantyliminomethyl)-
In many countries, amantadine (SymmetrelTM) 4-chlorophenolato-N,O)-copper(II) C H Cl Cu-
3
4
38
2
TM
and rimantadine (Flumadine ) have been regarded N O (I) and bis(2-(1-adamantyliminomethyl)-4-
2
2
as being efficacious for the prevention and treatment
of infections with influenza A because they could
inhibit the early stages of virus replication by blocking
bromophenolato-N,O)-copper(II)
C H Br Cu-
34 38 2
N O (II) with ligands derived from amantadine and
2
2
1
2
5-halogenated (Cl, Br) salicylaldehyde (HL , HL ),
1
The article is published in the original.
respectively, were synthesized.
787

7
88
JIN et al.
X
N
O Cu
N
X
O
N
H O
X
1
2
I: X = Cl; II: X = Br
HL : X = Cl; HL : X = Br
3
Their structures were characterized by the means of (d., J = 9.6, 1H, Ar–H); 7.27–7.15 (m., 2H, Ar–H);
IR, UV-Vis, elemental analysis, molar conductance, 2.19 (s., 3H, CH, adam. H); 1.83 (s., 6H, CH , adam.
2
and single-crystal X-ray diffraction. More over, the
electrochemical behavior of the complexes was inves-
tigated by cyclic voltammetry in dimethylformamide
H); 1.79–1.67 (m., 6H, CH , adam. H).
2
For C H NOCl (M = 289.80)
17
20
(
DMF). The biological activity studies of two com-
Anal. calcd., %: C, 70.46;
H, 6.96;
H, 7.01;
N, 4.83.
N, 4.80.
plexes are in progress and will be reported later.
Found, %:
C, 70.40;
EXPERIMENTAL
2
HL : 521 mg, yield 78%, yellow powder, m.p.
Materials and methods. All chemicals and solvents
were purchased from Sinopharm Chemical Reagent
Co., Ltd, they were analytical grade and used without
any further purification. Elemental analysis was car-
ried out on Perkin Elmer Flash EA 1112. Chemical
–4
1
42.5–143.2°C. UV-Vis (hexane, c = 0.67 × 10 mol/L):
λ
= 230 (1.460), 252 (0.522), 328 (0.199); λ
=
max
min
–1
2
48 (0.494), 290 (0.036). IR (KBr; ν, cm ): 3463 w,
2
913 s, 2848 m, 2349 w, 1627 s, 1604 m, 1571 w, 1480 s,
1
345 w, 1310 w, 1279 m, 1192 m, 1118 m, 1088 m,
1
shifts (δ) for H NMR spectra were recorded
9
85 w, 881 m, 819 m, 788 w, 744 w, 626 w, 561 w.
at 300 MHz on a Varian Mercury-Vx300 spectrometer
1
H NMR (CDCl , 300 MHz; δ, ppm): 14.55 (s., 1H,
3
in CDCl solvent containing TMS as an internal stan-
3
Ar–OH), 8.23 (s., 1H, CH=N), 7.36 (s., 1H, Ar–H);
dard. IR spectrum was scanned in the range 4000–
3
4
7
.34 (d.d., J = 8.7, J = 2.4, 1H, Ar–H); 6.83 (d.d.,
–
1
4
00 cm with KBr pellets on a Nicolet NEXUS FT-
3
4
J = 8.1, J = 1.2, 1H, Ar–H); 2.19 (s., 3H, CH, adam.
IR 5700 spectrophotometer. UV-Vis spectrum was
measured on a Perkin Elmer Lambda 25 spectropho-
tometer. Melting points were measured on a WRS-1B
micro melting point apparatus which were uncor-
H); 1.83–1.67 (m., 12H, CH , adam. H).
2
For C H NOBr (M = 334.25)
1
7
20
rected. The molar conductance of the complexes in Anal. calcd., %:
C, 61.09;
C, 61.01;
H, 6.03;
H, 6.05;
N, 4.19.
N, 4.10.
–3
DMF (1.0 × 10 M) was measured on a DDS-11A Found, %:
conductometer.
Synthesis of ligands. Two Schiff base ligands were
Synthesis of complexes. Two complexes were pre-
prepared analogously to the literature [19]. Adaman- pared in a similar procedure starting from their corre-
taneamine 3.03 g (0.02 mol) in 20 mL anhydrous alco- sponding newly synthetic Schiff base ligands, NaOH
hol was added to a solution 2.0 mM 5-halogenated and copper(II) chloride dihydrate in anhydrous meth-
salicylaldehyde in 50 mL anhydrous alcohol. The anol, respectively.
mixture was refluxed for 1 h and then cooled to room
A solution of NaOH (80 mg, 2.0 mmol) in 10 mL
of anhydrous methanol was added gradually to a solu-
tion of a ligand (2.0 mmol) in 10 mL of anhydrous
methanol. The mixture was stirred at 30°C for 10 min,
temperature. A colored solid was filtered off and
washed with anhydrous alcohol three times and air
dried.
1
HL : 440 mg, yield 76%, yellowish powder, then copper(II) chloride dihydrate (170 mg,
m.p. 131.5–132.2°C. UV-Vis (hexane, c = 0.67 × 1.0 mmol) in 10 mL of anhydrous methanol was added
‒
4
dropwise. The mixture was refluxed for about 1.5 h,
and then cooled to room temperature. The pearlescent
solids were suction filtered, washed with small amount
anhydrous methanol and dried under vacuum.
1
0 mol/L): λ
= 228 (1.614), 254 (0.597), 328
max
(
0.239); λ = 244 (0.496), 290 (0.032). IR (KBr; ν,
min
–
1
cm ): 3502 w, 2917 s, 2848 m, 1629 s, 1607 m, 1576 m,
1
512 w, 1484 s, 1455 w, 1389 w, 1369 w, 1343 m, 1311 w,
I: 372 mg, yield 58%, brown powder, m.p. 225.8°C.
1
9
6
278 s, 1226 w, 1196 m, 1121 m, 1103 m, 1089 s, 983 w,
44 w, 916 w, 877 m, 825 s, 792 m, 752 m, 694 w, UV-Vis (hexane, c = 0.25 × 10– mol/L): λmax = 258
4
1
49 w, 565 w. H NMR (CDCl ; 300 MHz; δ, ppm): (0.942), 324 (0.357), 388 (0.627), 502 (0.112); λmin
=
3
–
1
1
4.51 (s., 1H, Ar–OH); 8.24 (s., 1H, CH=N); 6.87 304 (0.311), 344 (0.284), 466 (0.105). IR (KBr; ν, cm ):
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY
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2017

SYNTHESIS, CHARACTERIZATION, CRYSTAL STRUCTURE
789
2
907 s, 2850 m, 2341 m, 1610 s, 1528 m, 1461 s, perchlorate (TBAP) in DMF. During the cyclic vol-
1
388 m, 1344 w, 1325 m, 1269 w, 1242 w, 1189 m, tammetry measurement, a constant flux of N was
2
1
173 m, 1131 w, 1105 w, 1075 m, 931 w, 874 w, 819 m, kept over the solution surface in order to check the dif-
7
85 w, 756 w, 694 w, 661 w, 550 w.
fusion of atmospheric oxygen into the solution. All
measurements were carried out at room temperature.
The electroactivity range for this system was 3.0 V
For C H N O Cl Cu (M = 641.10)
3
4
38
2
2
2
(
from –1.5 to 1.5 V vs. SCE) at a scan rate of 100 mV
Anal. calcd., %: C, 63.64;
Found, %: C, 63.73;
H, 5.93;
H, 5.94;
N, 4.37.
N, 4.36.
–1
s . The data were integrated by using the OriginPro 8
program.
II: 415 mg, yield 57%, taupe powder, m.p. 207.9°C.
–4
UV-Vis (hexane, c = 0.25 × 10 mol/L): λ = 258
RESULTS AND DISCUSSION
max
(
0.907), 317 (0.390), 385 (0.647), 501 (0.112); λ
=
min
By analyzing the presence of C, H, and N contents,
it turned out to be that both complexes consist of one
copper(II) and two corresponding deprotonated
ligands. All compounds were soluble in both dichloro-
methane and chloroform; however, the complexes
were less soluble than the ligands in other solvents
such as ethanol, tetrahydrofuran, benzene and ethyl
–
1
3
09 (0.387), 343 (0.342), 467 (0.105). IR (KBr; ν, cm ):
2
904 m, 2849 w, 1608 s, 1542 w, 1524 m, 1461 s,
1
387 m, 1324 m, 1267 w, 1189 m, 1172 m, 1132 w,
105 w, 1072 m, 926 w, 874 w, 818 m, 747 w, 647 w,
06 w, 551 w.
1
6
For C H Br CuN O (M = 730.02)
3
4
38
2
2
2
acetate. The molar conductance values (Λ ) for I and
M
2
–1
Anal. calcd., %: C, 55.89;
Found, %: C, 55.93;
H, 5.21;
H, 5.27;
N, 3.84.
N, 3.83.
II were 3.50 and 4.11 S cm mol , which were much
less than 18 S cm mol , indicating non-electrolyte
behavior of the complexes [27].
2
–1
X-ray crystallography. The crystals of two com-
plexes suitable for X-ray analysis developed from a
solution of CH OH–CH Cl (1 : 1 v/v) through slow
The OH stretching vibration of phenol was mostly
–1
reported to be 3657 cm [28, 29], which red-shifted to
–1
3
2
2
3
502 and 3463 cm in free ligands, indicating that
evaporation. The crystallographic data collections
were conducted on a Bruker Smart Apex II CCD with
intramolecular hydrogen bonding was formed. These
bands disappeared after the coordination of copper,
proving that the hydrogen of phenol was substituted
with the copper(II) ion and these bands vanished nat-
urally in complexes. The spectra of the free ligands
graphite-monochromated MoK radiation (λ
=
α
0
.71073 Å) using the ω-scan technique. The data were
integrated by using the SAINT program, which also
corrected the intensities for Lorentz and polarization
effect [24]. An empirical absorption correction was
applied using the SADABS program [25]. The struc-
tures were solved by direct methods using the program
SHELXS-97 and all non-hydrogen atoms were
1
2
HL and HL showed strong bands at 1629 and
–1
1
627 cm which assigned to the C=N stretching
vibration. These bands red-shifted towards lower wav-
–1
–1
enumber of 1610 cm for I and 1608 cm for II in
compared with ligands indicating a coordination of
azomethine nitrogen to chelation with the copper(II)
ion. The spectra of ligands displayed strong bands at
2
refined anisotropically on F by the full-matrix least-
squares technique using the SHELXL-97 crystallo-
graphic software package [26]. The hydrogen atoms
were generated geometrically. All calculations were
–1
1
278 and 1279 cm , was assigned to the C–O stretch-
ing vibration. These bands also occurred in complexes
performed on
a personal computer with the
–1
at lower frequency 1173 and 1172 cm . The absorption
SHELXL-97 crystallographic software package. The
details of the crystal parameters, data collection and
refinement are summarized in Table 1. Selected bond
lengths and angles with their estimated standard devi-
ations are given in Table 2. The molecular structures
–1
–1
peak at 550 cm for I and 551 cm for II were
attributed to Cu–O vibration, indicating that oxygen
atoms of the ligands were coordinated to metal ions.
UV-Vis spectra of the ligands are shown in Fig. 1.
for the complexes were generated with the XP feature Two complexes exhibited significant changes in the
of SHELXTL.
ultraviolet and visible spectra compared to their corre-
1
sponding ligands. Bands at 228 nm for HL and
Electrochemical studies. The complexes were
2
58 nm for I were attributed to π–π* transitions of the
investigated by cyclic voltammetry. They were pre-
1
–3
benzene ring. Bands at 328 nm for HL were attributed
pared with concentration of 1.0 × 10 mol/L in DMF.
Electrochemical data was collected using a CHI 660E
Electrochemical Workstation (Shanghai Chenhua). A
three-electrode cell was used for all electrochemical
to n–π* transitions of the p–π conjugation. Bands at
3
24 nm for I were assigned to n–π* transitions from
the ligands to copper(II) (n–π* transition) of N → Cu
2
experiments. This system consisted of glassy carbon and O → Cu. Bands at 230 nm for HL and 258 nm for
(
working), platinum wire (counter) and Ag/AgCl (ref- II were attributed to π–π* transitions of the benzene
2
erence) electrodes. Test solutions contained 1 mM ring. Bands at 328 nm for HL were attributed to n–π*
copper(II) complex and 0.15 M tetrabutylammonium transitions of the p–π conjugation. Bands at 317 nm
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 43 No. 11 2017

7
90
JIN et al.
Table 1. Crystallographic data and and structure refinement for complexes I and II
Value
Parameter
I
II
Fw
641.10
730.02
Crystal size, mm
Crystal system
Space group
a, Å
b, Å
c, Å
0.40 × 0.30 × 0.20
Monoclinic
0.18 × 0.16 × 0.14
Monoclinic
P2 /c
P2 /c
1
1
21.8285(17)
11.5879(7)
25.2549(17)
106.344(7)
21.944(10)
11.620(5)
25.549(11)
106.767(4)
6238(5)
β, deg
V, Å3
6130.0(7)
Z
8
8
F(000)
Index ranges
2680
–25 ≤ h ≤ 19,
2968
–24 ≤ h ≤ 25,
–13 ≤ k ≤ 137,
–30 ≤ l ≤ 30
–
–
13 ≤ k ≤ 12,
25 ≤ l ≤ 30
.389
.920
ρ, g cm–3
µ, mm–1
1
1.555
0
3.300
Reflections collected/unique (Rint)
Data/restraints/parameters
GOOF
23816/10783 (0.042)
10783/0/739
1.126
33736/10657 (0.056)
10657/0/739
1.058
T, K
298(2)
293(2)
R /wR (I > 2σ(I))*
0.0923/0.1794
0.1307/0.1962
0.0763/0.1912
0.1028/0.2130
2.62/–0.75
1
2
R /wR (all data)
1
2
Largest difference peak and hole, e Å–3
2.17/–0.58
R = Σ||F | – |F ||/|F |; wR = [Σw(F – F ) /Σw(F )2]1/2.
2
2
2
2
*
1 o c o 2
o c o
for II were assigned to n–π* transitions from the and defined by C(3)C(4)C(5) and C(19)C(20)C(21)
ligands to copper(II) (n–π* transition) of N → Cu and of 54.56° for II. Bond angles also show that the coor-
O → Cu. Broad peaks at 388 nm for I and 385 nm for dination geometry about the copper atom in I is dis-
II could be caused by d → d* transition of copper(II), torted tetrahedral (τ = [360 – (α + β)]/141° = 0.57)
4
which could not be found in the ligands. These
changes between the ligands and complexes, as we
predicted, displayed different colors due to distin-
guishing structural features themselves.
with O(2)Cu(1)O(1) (α) and N(2)Cu(1)N(1) (β)
angles of 142.10(3)° and 137.44(9)°, respectively.
Complex II is distorted tetrahedral (τ = [360 – (α +
4
β)]/141° = 0.54) [31] with N(2)Cu(1)N(1) (α) and
O(2)Cu(1)O(1) (β) angles of 142.60(2)° and
The molecular structures for the complexes are
shown in Fig. 2. The central copper(II) atom in I and
II lies on a twofold rotation axis and is bonded to the
oxygen and nitrogen donor atoms of the two bidentate
ligands molecules in a trans-arrangement. The geom-
etry around copper(II) in I and II is intermediated
between square planar and tetrahedral, where the
1
41.90(2)°, respectively. Complexes I and II are
expected for a typical Schiff base ligand (containing a
short C=N bond distance of 1.289 Å for I and 1.284 Å
for II) coordinated to a metal centre, where the imine
form is predominant. The distinctly shortened Cu(1)–
O(1) and elongated Cu(1)–N(1) bonds in I and II are
dihedral angle between the two coordination planes 1.873–1.900 and 1.992–2.015 Å, respectively (the nor-
defined by O(1)Cu(1)N(1) and O(2)Cu(1)N(2) is mal bond length of them are about 1.940 and 1.960 Å),
5
5
1.35° for I, by O(1)Cu(1)N(1) and O(2)Cu(1)N(2) is so the coordination geometry around the copper(II)
2.12° for II [30]. The two phenyl rings are in the inter- ion reflects Jahn–Teller effect [32]. The distances of
secting planes with a dihedral angle defined by two neighboring copper atoms along the y axis are
C(1)C(6)C(5) and C(19)C(18)C(23) of 55.54° for I 6.895 Å in I and 6.839 Å in II. The bidentate coordi-
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY
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SYNTHESIS, CHARACTERIZATION, CRYSTAL STRUCTURE
Table 2. Selected bond length (Å) and angles (deg) in complexes I and II
Bond d, Å
791
Bond
d, Å
I
Cu(1)–O(1)
Cu(2)–O(3)
1
.878(5)
1.880(5)
1.900(5)
2.000(6)
2.010(6)
1.292(8)
1.294(9)
Cu(1)–O(2)
Cu(1)–N(1)
Cu(1)–N(2)
N(1)–C(7)
N(2)–C(24)
Cu(2)–O(4)
Cu(2)–N(3)
Cu(2)–N(4)
N(3)–C(41)
N(4)–C(58)
1.891(5)
2.009(6)
2.015(6)
1.286(8)
1.289(8)
II
Cu(1)–O(1)
Cu(1)–O(2)
Cu(1)–N(1)
Cu(1)–N(2)
N(1)–C(7)
N(2)–C(24)
Cu(2)–O(3)
Cu(2)–O(4)
Cu(2)–N(3)
Cu(2)–N(4)
N(3)–C(41)
N(4)–C(57)
1
.888(5)
.880(5)
.009(5)
.992(5)
.284(8)
.300(8)
ω, deg
1.873(5)
1.891(5)
1.995(6)
2.012(5)
1.296(8)
1.280(8)
ω, deg
1
2
1
1
1
Angle
Angle
I
O(1)Cu(1)O(2)
O(1)Cu(1)N(1)
O(1)Cu(1)N(2)
O(2)Cu(1)N(2)
O(2)Cu(1)N(1)
N(1)Cu(1)N(2)
O(3)Cu(2)O(4)
O(3)Cu(2)N(3)
O(3)Cu(2)N(4)
O(4)Cu(2)N(4)
O(4)Cu(2)N(3)
N(3)Cu(2)N(4)
1
42.1(3)
141.5(3)
93.8(2)
98.8(2)
95.4(2)
95.9(2)
143.2(2)
9
9
9
9
3.6(2)
8.5(2)
5.3(2)
5.9(2)
143.7(2)
II
O(1)Cu(1)O(2)
O(1)Cu(1)N(2)
O(1)Cu(1)N(1)
O(2)Cu(1)N(1)
O(2)Cu(1)N(2)
N(1)Cu(1)N(2)
O(3)Cu(2)O(4)
O(3)Cu(2)N(4)
O(3)Cu(2)N(3)
O(4)Cu(2)N(3)
O(4)Cu(2)N(4)
N(3)Cu(2)N(4)
1
41.9(2)
141.5(2)
98.4(2)
94.0(2)
96.1(2)
95.8(2)
142.5(2)
9
6.2(2)
5.5(2)
8.2(2)
4.1(2)
9
9
9
142.6(2)
(a)
(b)
1
.0
1.0
0.8
0.8
0.6
0.4
0.2
0.6
0.4
0.2
0
0
2
00 250 300 350 400 450 500 550 600
Wavelength, nm
200 250 300 350 400 450 500 550 600
Wavelength, nm
Fig. 1. UV-Vis spectra of complexes I (a) and II (b) (hexane, c = 2.5 × 10–5 mol/L).
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 43 No. 11 2017

7
92
JIN et al.
a)
(
C(17)
C(47)
C(46)
C(48)
C(12)
C(15)
C(49)
C(50)
C(13)
C(16)
C(51)
C(44)
C(14)
C(19)
C(43)
C(42)
N(3)
C(11)
C(20)
C(23)
C(10)
C(45)
Cl(1)
C(54)
C(8) C(9)
C(18)
C(53)
N(4)
C(21)
C(22)
Cl(4)
C(41) N(1)
C(7)
C(40)
C(52) O(4)
O(2)
C(55)
C(56)
Cu(2)
C(39)
C (( 33 88 ) C uu (( 11 ))
C(57)
C(58)
C(5)
O(3)
C(24)
N(2)
C(25)
C(62)
C(67)
C(6)
C(35)
C(59)
Cl(3)
C(60)
Cl(2)
C(4)
C(66)
C(65)
C(36)
C(1) O(1)
C(37)
C(68)
C(61)
C(28)
C(27)
C(26)
C(34)
C(29)
C(31)
C(63)
C(2)
C(33)
C(32)
C(3)
C(64)
C(30)
(b)
C(34)
C(30)
C(32)
C(48)
C(50)
C(33)
C(28)
C(31)
C(68)
C(47)
C(29)
C(6)
C(49)
C(46)
C(45)
C(44)
C(42)
C(41)
C(24)
C(5)
C(1)
C(26)
C(27) C(25)
C(43)
Br(1)
C(2)
C(4)
C(53)
C(54)
O(4)
C(52)
O(1) N(2)
N(3)
C(3)
C(51)
C(56)
Br(4)
C(40)
C(55)
C(57)
C(39)
C(38)
C(7)
C(8)
Cu(1)
N(1)
Cu(2)
C(61)
C(63)
C(35)
C(20)
C(19)
C(36)
N(4) C(65)
C(11)
Br(3)
O(3)
C(18)
C(59)
C(66)
C(9)
C(15)
O(2)
C(17)
C(12)
C(21)
C(58)
C(60)
C(37)
C(22)
C(10)
C(16)
Br(2)
C(64)
C(62)
C(23)
C(67)
C(14)
C(13)
Fig. 2. Molecular structures of I (a) and II (b). Thermal ellipsoids are drawn at 50% probability.
nation mode of complexes refrains themselves from lecular aromatic π···π interaction is presented between
forming intramolecular hydrogen bonds because of approximate parallel phenyl rings from different com-
plex molecules (Fig. 3). The distances between cen-
troids of two phenyl rings are 3.671 Å for I and 3.647 Å
for II.
the deprotonated ligands, but there also exists two six-
membered rings through a copper(II) ion, two oxygen
atoms and two nitrogen atoms in I and II [33]. Two
complexes are found not to possess intermolecular
The study of the electrochemical behavior of I and
hydrogen bonding in stacking, however the intermo- II was carried out in DMF with TBAP as supporting
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY
Vol. 43
No. 11
2017

SYNTHESIS, CHARACTERIZATION, CRYSTAL STRUCTURE
793
(a)
with associated anodic peak at Epa = –0.7232 V for
Cu(I) → Cu(II) of peak B. The ΔE = (E – E ) value
p
pa
pc
was 151.8 mV and the i /i = 1.72 relationship was far
pa pc
from unity [34]. This finding shows the quasi-revers-
ibility of this redox process. It’s been reported that the
Cu(II)L /[Cu(I)L ] reaction in most CuN O coordi-
2
2
2
2
nation complexes is quasi-reversible in nature due to
the fact that the [Cu(I)L ] species are chemically
2
decomposed to a copper ion, which subsequently is
reduced to copper metal [35]. Similar results were
obtained for II (with E = –1.1759 V, E = –1.0381 V,
pc
pa
3.671 Å
ΔE = 139.9 mV, i /i = 1.861). In the Fig. 4, two oxi-
p
pa pc
dation peaks were also observed.
(b)
Thus, two novel complexes were obtained from
copper(II) chloride dihydrate and two ligands derived
from amantadine and 5-halogenated salicylaldehyde,
respectively. The electrochemical properties of
the copper(II) complexes revealed the quasi-revers-
ible one electron transfer redox process. Single-crystal
X-ray diffraction analysis reveals that both complexes
consist of one copper(II) and two deprotonated Schiff
base ligands. Each Schiff base ligand serves as a biden-
tate ligand coordinating through an oxygen atom and
a nitrogen atom to copper(II) atom. The geometry
around copper(II) atom in complexes is distorted
square planar.
3.647 Å
ACKNOWLEDGMENTS
Fig. 3. Intermolecular aromatic π···π interaction for I (a)
and II (b). Hydrogens are omitted for clarity.
This work was financially supported by Foundation
of Liaoning Provincial Department of Education
Innovation Team Projects (LT2015012), the Cause of
electrolyte. The cyclic voltammogram of I (–1.5 to
1
.5 V) at a scan rate of 100 mV s–1 shows a quasi-
Public
Welfare
Scientific
Research
Fund
reversible peak in the negative region, characteristic of (2015005008), Shenyang Science and Technology
the Cu(II) → Cu(I) couple at E = –0.875 V of peak A Plan Project (F13-289-1-00).
pc
(a)
(b)
–
50
–100
0
A
A
0
B
B
50
100
100
200
150
2
1
0
Potential
–1
–2
2
1
0
–1
–2
Potential
Fig. 4. Cyclic voltammogram for complexes I (a) and II (b) in DMF solution.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 43 No. 11 2017

7
94
JIN et al.
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