Syntheses and crystal structures of copper(II) and nickel(II) complexes derived from 2-bromo-4-chloro-6-[(2-methylaminoethylimino)methyl]phenol

Article abstract of DOI:10.1134/S1070328416040059

A new centrosymmetric mononuclear copper(II) complex [Cu(L)₂](ClO₄)₂ (I) and a new centrosymmetric mononuclear nickel(II) complex [Ni(L)₂(MeOH)₂](ClO₄)₂ (II), where L is the zwit

Full text of DOI:10.1134/S1070328416040059

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2016, Vol. 42, No. 5, pp. 345–350. © Pleiades Publishing, Ltd., 2016.
Syntheses and Crystal Structures of Copper(II) and Nickel(II)
Complexes Derived from 2-Bromo-4-Chloro-6-[(2-
Methylaminoethylimino)methyl]phenol1
S. S. Qiana, X. L. Zhaob, L. H. Pangb, Z. L. Youb, *, and H. L. Zhua, *
aSchool of Life Sciences, Shandong University of Technology, ZiBo, 255049 P.R. China
bDepartment of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029 P.R. China
*e-mail: youzhonglu@126.com; hailiang_zhu@163.com
Received June 6, 2015
Abstract—A new centrosymmetric mononuclear copper(II) complex [Cu(L)2](ClO4)2 (I) and a new cen-
trosymmetric mononuclear nickel(II) complex [Ni(L)2(MeOH)2](ClO4)2 (II), where L is the zwitterionic
ligand 2-bromo-4-chloro-6-[(2-methylammonioethylimino)methyl]phenolate, have been prepared from
the Schiff base 2-bromo-4-chloro-6-[(2-methylaminoethylimino)methyl]phenol with copper perchlorate
and nickel perchlorate, respectively. The complexes were characterized by elemental analysis, infrared spec-
tra, and single-cyrstal X-ray diffraction (CIF files CCDC nos. 1408054 (I) and 1407973 (II)). Complex I
crystallizes in the monoclinic space group P21/c with unit cell dimensions a = 7.7736(4), b = 21.608(1), c =
8.5194(4) Å, β = 93.907(2)°, V = 1427.7(1) Å3, Z = 2, R1 = 0.0546, and wR2 = 0.1531. Complex II crystallizes
in the monoclinic space group P21/c with unit cell dimensions a = 21.324(3), b = 16.821(2), c = 9.425(1) Å,
β = 90.114(2)°, V = 3380.5(7) Å3, Z = 4, R1 = 0.0693, and wR2 = 0.1627. The Cu atom in I is in square planar
coordination, and the Ni atom in II is in octahedral coordination.
DOI: 10.1134/S1070328416040059
NH+2
INTRODUCTION
Cl
N
Schiff base complexes have been received consider-
able attention for their importance in the field of coor-
dination chemistry related to catalysis and enzymatic
reactions, magnetism and molecular architectures [1–
5]. Copper and nickel complexes with Schiff base
ligands have been proved to possess interesting biolog-
ical, catalytic, and magnetic properties [6–10].
During the search of literature, we found that a large
number of complexes with Schiff bases derived from
salicylaldehyde and its derivatives with versatile
organic amines had been reported. Yet, to the best of
our knowledge, only one complex derived from the
Schiff base 2-bromo-4-chloro-6-[(2-methylaminoe-
O−
Br
EXPERIMENTAL
Materials and measurements. Commercially avail-
able 3-bromo-5-chlorosalicylaldehyde and N-methy-
lethane-1,2-diamine were purchased from Aldrich
and used without further purification. Other solvents
and reagents were made in China and used as received.
C, H, and N elemental analyses were performed with
thylimino)methyl]phenol (L) has been reported [11]. a Perkin-Elmer elemental analyser. Infrared spectra
were recorded on a Nicolet AVATAR 360 spectrometer
As an extension of work on Schiff base complexes [12–
14], we report in this paper the syntheses and crystal
as KBr pellets in the 4000–400 cm–1 region. UV-Vis
structures of two new copper(II) and nickel(II) com- spectra were recorded on a Lambda 900 spec-
tromether.
plexes,
[CuL2](ClO4)2
(I)
and
[NiL2(MeOH)2](ClO4)2 (II), where L is the zwitteri-
onic ligand 2-bromo-4-chloro-6-[(2-methylam-
monioethylimino)methyl]phenolate.
Synthesis of the Schiff base. 3-Bromo-5-chlorosa-
licylaldehyde (1.0 mmol, 0.235 g) and N-me-
thyethane-1,2-diamine (1.0 mmol, 0.074 g) were dis-
solved in MeOH (20 mL) with stirring. The mixture
was stirred for about 30 min at room temperature to
1
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345

346
QIAN et al.
give yellow solution. The solvent was evaporated to cold methanol and dried in a vacuum over anhydrous
give yellow gummy product of the Schiff base.
CaCl2. The yield was 21.3 mg (47% on the basis of the
Schiff base).
For C10H12N2OClBr
For C22H32N4O12Cl4Br2Ni
anal. calcd., %:
Found, %:
C, 41.2;
C, 41.0;
H, 4.2;
H, 4.1;
N, 9.6.
N, 9.7.
anal. calcd., %: C, 29.20;
Found, %: C, 29.33;
H, 3.56;
H, 3.73;
N, 6.19.
N, 6.11.
Synthesis of I. A methanolic solution (5 mL) of
copper perchlorate (0.1 mmol, 37.0 mg) was added to
a methanolic solution (10 mL) of the Schiff base
(0.1 mmol, 29.2 mg) with stirring. The mixture was
stirred for 30 min to give blue solution. The resulting
solution was allowed to stand in air for a few days. Blue
block-shaped crystals suitable for X-ray single crystal
analysis were formed at the bottom of the vessel. The
isolated product was washed three times with cold
methanol, and dried in a vacuum over anhydrous
CaCl2. The yield was 17.2 mg (41% on the basis of the
Schiff base).
IR data (KBr; ν, cm–1): 3211 w, 1630 s, 1446 s,
1313 w, 1217 w, 1087 s, 856 m, 739 w, 622 w, 547 s,
473 w.
X-ray structure determination. Diffraction intensi-
ties for the complexes were collected at 298(2) K using
a Bruker SMART 1000 area-detector with MoKα radi-
ation (λ = 0.71073 Å). The collected data were reduced
using the SAINT program [15], and multi-scan
absorption corrections were performed using the
SADABS program [16]. The structures of the com-
plexes were solved by direct methods and refined
against F 2 by full-matrix least-squares methods using
the SHELXTL [17]. All of the non-hydrogen atoms
were refined anisotropically. Hydrogen atoms were
placed in ideal positions and constrained to ride on
their parent atoms. Crystallographic data for the com-
plexes are summarized in Table 1. Selected bond
lengths and angles are given in Table 2. Supplementary
material has been deposited with the Cambridge Crys-
tallographic Data Centre (nos. 1408054 (I) and
1407973 (II)); deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk).
For C20H24N4O10Cl4Br2Cu
anal. calcd., %:
Found, %:
C, 28.41;
C, 28.23;
H, 2.86;
H, 2.97;
N, 6.63.
N, 6.77.
IR data (KBr; ν, cm–1): 3195 w, 1626 s, 1446 s,
1324 w, 1212 w, 1084 s, 856 m, 808 w, 744 w, 622 w,
547 s.
Synthesis of II. A methanolic solution (5 mL) of
nickel perchlorate (0.1 mmol, 36.6 mg) was added to a
methanolic solution (10 mL) of the Schiff base
(0.1 mmol, 29.2 mg) with stirring. The mixture was
stirred for 30 min to give green solution. The resulting
solution was allowed to stand in air for a few days.
Green block-shaped crystals suitable for X-ray single
crystal analysis were formed at the bottom of the ves-
RESULTS AND DISCUSSION
Complexes I and II were readily prepared by the
sel. The isolated product was washed three times with similar synthetic procedure:
NH2
2+
Cl
H
N
N
Cl
Br
Br
N
2ClO4−
+ Cu(ClO4)2
O
Cu
O
OH
Br
N
Br
Br
Cl
NH2
NH2
2+
Cl
N
H
N
Cl
HOMe
O
N
O
+ Ni(ClO4)2
Ni
2ClO4−
Br
OH
MeOH
NH2
N
Cl
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SYNTHESES AND CRYSTAL STRUCTURES
347
Table 1. Crystallographic data and structure refinement details for I and ІІ
Value
Parameter
I
II
Fw
845.6
Block/blue
0.33 × 0.30 × 0.26
Monoclinic
P21/c
904.8
Block/green
0.30 × 0.27 × 0.23
Monoclinic
P21/c
Crystal shape/color
Crystal size, mm
Crystal system
Space group
a, Å
7.7736(4)
21.324(3)
b, Å
c, Å
β, deg
21.6078(11)
8.5194(4)
93.907(2)
16.821(2)
9.4246(13)
90.114(2)
V, Å3
1427.68(12)
3380.5(7)
Z
2
4
μ(MoKα), mm–1
ρcalcd, g cm–3
3.998
3.316
1.967
1.778
F(000)
Tmin/Tmax
838
0.3521/0.4229
13120/2661 (0.346)
2201
1816
0.4362/0.5160
29684/5989 (0.797)
3587
Collected reflections/unique (Rint
Observed reflections (I ≥ 2σ(I))
Refinement parameters
)
188
413
Goodness of fit on F 2
R1, wR2 (I ≥ 2σ(I))*
R1, wR2 (all data)*
1.048
1.030
0.0546, 0.1531
0.0677, 0.1628
1.271, –1.255
0.0693, 0.1627
0.1272, 0.1973
1.071, –0.684
Large diff. peak and hole, e Å–3
2
2
2
2 1/2
2
* R = ∑||F | – |F ||/∑|F |, wR = [∑w(
–
) /∑w( ) ]
.
Fo
Fc
Fo
1
o
c
o
2
Table 2. Selected bond lengths (Å) and angles (deg) in structures I and II*
Bond
d, Å
Bond
d, Å
I
Cu(1)–O(1)
1.907(4)
Cu(1)–N(1)
2.013(4)
II
Ni(1)–O(1)
Ni(1)–O(2)
Ni(2)–N(3)
2.015(5)
2.120(5)
2.082(6)
Ni(1)–N(1)
Ni(2)–O(3)
Ni(2)–O(4)
2.081(6)
2.012(5)
2.124(5)
Angle
ω, deg
Angle
ω, deg
I
O(1)Cu(1)N(1)
91.44(17)
II
O(1)Ni(1)O(2)
N(3)Ni(2)O(4)
O(1)Ni(1)N(1)
83.9(2)
90.1(2)
89.1(2)
N(1)Ni(1)O(2)
O(3)Ni(2)N(3)
O(3)Ni(2)O(4)
89.8(2)
89.3(2)
83.9(2)
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348
QIAN et al.
(a)
C(10)
N(2)
Cu(1)
C(9)
C(8)
O(1) N(1)
O(5)
Cl(2)
C(2) C(7)
O(4)
Br(1)
C(1)
O(2)
C(6)
C(5)
O(3)
C(3)
C(4)
Cl(1)
(b)
Cl(1)
C(5)
C(4)
C(3)
C(6)
C(7)
C(8)
C(1)
C(9)
C(10)
O(10)
Cl(4)
N(1)
N(2)
Ni(1) C(2)
O(1)
Br(1)
O(11)
C(11)
O(2)
O(9)
O(12)
Fig. 1. Molecular structures of I (a) and II (b) at 30% probability displacement. Unlabeled atoms are at the symmetry positions:
1 — x, 1 – y, 1 — z for I and –x, –y, 1 — z for II.
The complexes are similar with a mononuclear the complex cation is coordinated by two phenolate O
complex cation and two perchlorate anions. The main
difference lies in the central metal ions and their coor-
dination geometries. In I, the Cu atom is in square pla-
nar geometry, while in II, the Ni atom is in octahedral
geometry.
and two imine N atoms from two Schiff base ligands,
forming a square planar geometry. The Cu–O and
Cu–N bond lengths in complex I are comparable to
the corresponding values observed in other Schiff base
copper(II) complexes [18, 19]. In the crystal structure
of complex I, molecules are linked through intermo-
lecular N–H···O (N(2)–H(2B) 0.90, H(2B)···O(3)i
The molecular structure of complex I is shown in
Fig. 1a. The compound is a centrosymmetric mono-
nuclear copper(II) complex. There are two perchlo-
rate counteranions in the compound. The Cu atom in 1.97, N(2)···O(3)i 2.821(8) Å, N(2)–H(2B)···O(3)i
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SYNTHESES AND CRYSTAL STRUCTURES
1.0
349
(a)
0.8
0.6
z
y
0
II
0.4
I
0.2
0
x
300
400
500
λ, nm
600
700
800
(b)
Fig. 3. UV-Vis spectra of complexes I and II.
z
lecular N–H···O (N(4)–H(4B) 0.90, H(4B)···O(4)ii
2.32, N(4)···O(4)ii 3.020(9) Å, N(4)–H(4B)···O(4)ii
135°; N(4)–H(4A) 0.90, H(4A)···O(3)ii 2.03,
N(4)···O(3)ii 2.807(9) Å, N(4)–H(4A)···O(3)ii 144°;
N(4)–H(4A) 0.90, H(4A)···Br(2)ii 2.80, N(4)···Br(2)ii
3.494(8) Å, N(4)–H(4A)···Br(2)ii 135°; O(4)–H(4C)
0.93, H(4C)···N(4)ii 2.51, O(4)···N(4)ii 3.020(9) Å,
O(4)–H(4C)···N(4)ii 115°; O(4)–H(4C) 0.93,
H(4C)···O(11)iv 2.26, O(4)···O(11)iv 2.755(9) Å, O(4)–
H(4C)···O(11)iv 113°; symmetry code: iv 1 – x, –y, –z)
hydrogen bonds, forming dimmers, as shown in
Fig. 2b.
0
y
x
IR spectra of the two complexes are very similar.
The weak and sharp bands at 3195 cm–1 for I and
3211 cm–1 for II are assigned to the N–H streching
vibration. The strong absorption bands at 1626 cm–1
for I and 1630 cm–1 for II are assigned to the azome-
thine groups, ν(C=N). The phenolate ν(Ar–O) in the
complexes exhibit weak bands at 1212 cm–1 for I and
1217 cm–1 for II. The intense bands centered at about
1085 cm–1 for the complexes are assigned to the
stretching vibrations of the perchlorate anions. The
weak bands located at the low numbers may be
assigned to the ν(M–O) and ν(M–N).
Fig. 2. Molecular packing structures of I (a) and II (b),
viewed along the z axis. Hydrogen bonds are shown as
dashed lines.
158°; N(2)–H(2A) 0.90, H(2A)···O(4)ii 2.32,
N(2)···O(4)ii 2.989(8) Å, N(2)–H(2A)···O(4)ii 131°;
N(2)–H(2A) 0.90, H(2A)···O(4)iii 2.20, N(2)···O(4)iii
2.936(8) Å, N(2)–H(2A)···O(4)iii 139°; symmetry
codes: i –x, 3/2 + y, 3/2 – z; ii 1 – x, 3/2 + y, 3/2 – z;
iii x, y, 1 + z) hydrogen bonds, forming chains running
along the x axis direction, as shown in Fig. 2a.
UV-Vis spectra of the two complexes recorded in
acetonitrile are very similar (Fig. 3). The bands cen-
tered at about 340 nm are attributed to the azomethine
chromophore π–π* transition. The bands at higher
energies (340 nm) are associated with the benzene π–
π* transition [22]. The bands centered at 383 nm for I
and 394 nm for II may assigned to LMCT.
The molecular structure of complex II is shown in
Fig. 1b. The compound is a centrosymmetric mono-
nuclear nickel(II) complex. There are two perchlorate
counteranions in the asymmetric unit of the com-
pound. The Ni atom in the complex cation is coordi-
nated by two phenolate O and two imine N atoms from
two Schiff base ligands, and two methanol O atoms,
forming an octahedral geometry. The Ni–O and Ni–
N bond lengths in complex II are comparable to the
corresponding values observed in other Schiff base
nickel(II) complexes [20, 21]. In the crystal structure
of complex II, molecules are linked through intermo-
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