Synthesis, characterization, and X-ray crystal structures of copper(I) halide and pseudohalide complexes with 2-(2-quinolyl)benzothiazole. Diverse coordination geometries and electrochemical properties

Article abstract of DOI:10.1016/j.crci.2017.02.005

Three new copper(I) complexes with the ligand 2-(2-quinolyl)benzothiazole (qbtz) have been synthesized and characterized by elemental analyses, infrared, and ultraviolet–visible spectroscopy, and their crystal structures have been determined by X-ray diffraction. The coordination geometry around copper in [Cu(qbtz)(μ-I)]₂, complex (1), a centrosymmetric dimer, is a distorted CuI₂N₂ tetrahedron supplemented by a short Cu?Cu interaction of 2.5855 ?. The copper(I) cyanide–bridged complex [Cu₃(qbtz)₂(μ-CN)₃] (2) exhibits a one-dimensional chain structure with three crystallographically independent Cu atoms. Two of the copper atoms feature tetrahedral four coordination each by a chelating qbtz ligand and two CN groups, and the third features a quasi-linear two-coordination geometry by two CN. In [Cu(qbtz)(μ-SCN)] (3), copper is in a distorted tetrahedral coordination by two N atoms of a chelating qbtz ligand and by one N atom and one S atom of a bridging SCN group. The complex exhibits a one-dimensional zigzag chain structure with two crystallographically inequivalent Cu atoms in the chain. The spectroscopic and electrochemical properties of compounds 1–3 are in accord with the variation in copper(I) coordination environments.

Full text of DOI:10.1016/j.crci.2017.02.005

C. R. Chimie xxx (2017) 1e8
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www.sciencedirect.com
Full paper/M eꢀ moire
Synthesis, characterization, and X-ray crystal structures
of copper(I) halide and pseudohalide complexes with
2
-(2-quinolyl)benzothiazole. Diverse coordination
geometries and electrochemical properties
Soraia Meghdadi a, , Mehdi Amirnasr a , Elaheh Yavari , Kurt Mereiter ,
Maryam Bagheri
a
*
,
**
a
b
a
Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran
Faculty of Chemistry, Vienna University of Technology, Getreidemarkt 9/164SC, A-1060 Vienna, Austria
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Three new copper(I) complexes with the ligand 2-(2-quinolyl)benzothiazole (qbtz) have
been synthesized and characterized by elemental analyses, infrared, and ultravioletevisible
spectroscopy, and their crystal structures have been determined by X-ray diffraction. The
Received 16 December 2016
Accepted 20 February 2017
Available online xxxx
coordination geometry around copper in [Cu(qbtz)(
dimer, is a distorted CuI tetrahedron supplemented by a short Cu/Cu interaction of
.5855 Å. The copper(I) cyanideebridged complex [Cu (qbtz) -CN) ] (2) exhibits a one-
2
m-I)] , complex (1), a centrosymmetric
2 2
N
Keywords:
2
3
2
(
m
3
Benzothiazole
dimensional chain structure with three crystallographically independent Cu atoms. Two
of the copper atoms feature tetrahedral four coordination each by a chelating qbtz ligand
and two CN groups, and the third features a quasi-linear two-coordination geometry by two
Copper(I) complexes
Halide and pseudohalide
X-ray structure
CN. In [Cu(qbtz)(m-SCN)] (3), copper is in a distorted tetrahedral coordination by two N
Cyclic voltammetry
atoms of a chelating qbtz ligand and by one N atom and one S atom of a bridging SCN group.
The complex exhibits a one-dimensional zigzag chain structure with two crystallographi-
cally inequivalent Cu atoms in the chain. The spectroscopic and electrochemical properties
of compounds 1e3 are in accord with the variation in copper(I) coordination environments.
©
2017 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.
1. Introduction
properties [10e13] and have found important applications
in bioinorganic chemistry [14,15] and for the preparation of
Copper as the third most abundant transition metal in
functional materials [16e18].
the human body is vital for both environmental and bio-
logical systems [1,2]. Copper(I) complexes have attracted
much attention because of their rich coordination chem-
istry and numerous catalytic and technological applications
Benzothiazole and its derivatives exhibit a wide range of
biological activities [19] and have potential clinical appli-
cations, as antitumor [20], anticoagulant [21], antiallergic
[22], anti-inflammatory [23], antimicrobial [24], and
enzyme inhibitor agents [25]. The electro-optical charac-
teristics of these materials as dopant in organic light-
emitting diode devices have also been investigated [26].
In continuation of our studies on copper complexes of 2-
substituted benzothiazoles [27,28], herein we report the
synthesis and spectral characterization of three Cu(I)
complexes of 2-(2-quinolyl)benzothiazole (qbtz) with
[3e9]. The copper(I) complexes of diimine ligands exhibit
structural diversity and rich redox and photophysical
*
Corresponding author.
** Corresponding author.
E-mail addresses: smeghdad@cc.iut.ac.ir (S. Meghdadi), amirnasr@
cc.iut.ac.ir (M. Amirnasr).
http://dx.doi.org/10.1016/j.crci.2017.02.005
1631-0748/© 2017 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Please cite this article in press as: S. Meghdadi, et al., Synthesis, characterization, and X-ray crystal structures of copper(I) halide
and pseudohalide complexes with 2-(2-quinolyl)benzothiazole. Diverse coordination geometries and electrochemical proper-
ties, Comptes Rendus Chimie (2017), http://dx.doi.org/10.1016/j.crci.2017.02.005

2
S. Meghdadi et al. / C. R. Chimie xxx (2017) 1e8
diverse structures, namely [Cu(qbtz)(
(m-CN) ] (2), and [Cu(qbtz)(m-SCN)] (3). The X-ray crystal
3
structures of these complexes are reported and their cyclic
voltammetric behavior is also discussed.
m
-I)]
2
(1), [Cu
3
(qbtz)
2
solution of qbtz (78.6 mg, 0.30 mmol) in 90 mL of aceto-
nitrile. To the resulting yellow solution was then added
dropwise a solution of KCN (19.5 mg, 0.30 mmol) in
acetonitrile (90 mL). The final solution was left undisturbed
at room temperature. Orange crystals of the product suit-
able for X-ray crystallography were obtained after 5 days.
The crystals were collected by filtration, washed with cold
acetonitrile, and dried in vacuum. Yield: 72%. Anal. Calcd for
2
. Experimental section
2
.1. Materials and methods
C
5
35 3 7 2
H20Cu N S : C, 52.90; H, 2.54; N,12.36; S, 8.08. Found: C,
ꢀ
1
2.82; H, 2.30; N, 12.34; S, 8.40%. FT-IR (KBr, cm
max
) n :
All solvents and chemicals were of commercial reagent
grade and used as received from Aldrich and Merck. Infrared
1591 (C]Nbenzothiazole), 1510 (C]Nquinoline), 2104 (C^N).
ꢀ
1
ꢀ1
UVevis:
l
max(nm) ( , L mol cm ) (DMF): 418 (358), 350
3
(
6
IR) spectra as KBr pellets were collected on a FT-IR JASCO
80 plus spectrometer in the range 4000e400 cm . Ultra-
(46,100), 336 (49,750), 320 (43,420), 284 (42,020), 264
(42,950).
ꢀ1
violetevisible (UVevis) absorption spectrawere recorded on
a JASCO V-570 spectrophotometer. Elemental analyses were
performed using a Perkin Elmer 2400II CHNSO Elemental
Analyzer. Electrochemical measurements were carried out at
room temperature with an SAMA 500 Research Analyzer
using a three-electrode system, a glassy carbon working
electrode (Metrohm 6.1204.110 with 2.0 ± 0.1 mm diameter),
a platinum disk auxiliary electrode, and an Ag wire as
reference electrode. Cyclic voltammogram measurements
were performed in DMF with tetrabutylammonium hexa-
fluoridophosphate as the supporting electrolyte. The solu-
tions were deoxygenated by purging with Ar for 5 min. All
electrochemical potentials were calibrated versus an inter-
2.5. Synthesis of [Cu(qbtz)(m-SCN)] (3)
Complex 3 was prepared by a procedure similar to that
used for complex 2, except that KSCN was used instead of
KCN. Brown crystals of the product suitable for X-ray
crystallography were obtained after 1 week. The crystals
were collected by filtration, washed with cold acetonitrile,
and dried in vacuum. Yield: 79%. Anal. Calcd for
34 2 6 4
C H20Cu N S : C, 53.18; H, 2.63; N, 10.94; S, 16.70. Found:
C, 52.86; H, 2.58; N, 10.88; S, 16.56%. FT-IR (KBr, cm
ꢀ1
max
) n :
1588 (C]Nbenzothiazole), 1508(C]Nquinoline), 2094 (SCN). UV
ꢀ
1
ꢀ1
evis:
l
max(nm) ( , L mol cm ) (DMF): 422 (376), 348
3
þ/0
0
nal Fc
(E ¼ 0.45 V vs saturated calomel electrode (SCE))
(76,300), 336 (81,260), 320 (70,980), 284 (68,260), 262
(59,530).
couple under the same conditions [29].
2
.2. Synthesis of the ligand qbtz
2.6. X-ray crystallography
The ligand qbtz was prepared according to a novel pro-
X-ray data of the compounds 1, 2, and 3 were collected
at T ¼ 100 K on a Bruker Kappa APEX-II CCD diffractometer
cedure reported elsewhere [28] by heating a mixture of
quinaldic acid and 2-aminothiophenol with triphenylphos-
phite in the presence of the inexpensive ionic liquid tetra-
with graphite monochromated Mo K
a
(l
¼ 0.71073 Å) ra-
diation. Cell refinement and data reduction were per-
formed with program SAINT [30]. Correction for absorption
was carried out by the multiscan method and program
SADABS [30]. The crystal structures were solved with direct
methods using the program SHELXS97, and structure
ꢁ
butylammonium bromide at 120 C. The reaction was
completed in 15 min. The viscous slurry obtained was treated
with methanol and the resulting solid was filtered and
washed with cold methanol and dried in vacuum. Yield: 87%.
2
refinement on F was carried out with the program
2
.3. Synthesis of [Cu(qbtz)(
m
-I)]
2
(1)
SHELXL97 [31]. Crystal data together with other relevant
information on the structure determination are summa-
rized in Table 1. All crystal structures had in common an
orientation disorder of the qbtz ligand by which the ben-
zothiazole and the quinoline fragment switch positions so
To a solution of CuI (28.6 mg, 0.15 mmol) in acetonitrile
45 mL) was added dropwise and slowly a solution of the
(
ligand (39.3 mg, 0.15 mmol) in acetonitrile (45 mL). The
resulting yellow solution was left undisturbed at room
temperature and brown crystals suitable for X-ray crystal-
lography were obtained by slow vaporization of the solvent
after 10 days. The crystals were filtered off, washed with
cold acetonitrile, and dried in vacuum. Yield: 76%. Anal.
0
that the two sides of the N,N -diphenylethane-1,2-diimine
fragment of qbtz practically coincide and only the sulfur
of the thiazole ring and a CH]CH group of the quinoline
ring give separate split positions. In solid-state structures
0
qbtz mimics thereby 2,2 -biquinoline. The proportions of
Calcd for C32
H
20
I
2
Cu
2
N
4
S
2
: C, 42.44; H, 2.23; N, 6.19; S, 7.08.
major to minor qbtz orientation varied between 0.677(5)
and 0.323(5) in compound 1 and 0.800(4) and 0.200(4) in
compound 3. This disorder made it necessary to apply
ꢀ
1
Found: C, 42.52; H, 2.25; N, 6.15; S, 7.32%. FT-IR (KBr, cm
)
n
max: 1584 (C]Nbenzothiazole), 1504 (C]Nquinoline). UVevis:
ꢀ
1
ꢀ1
0
lmax(nm) (
3 , L mol cm ) (DMF): 422 (380), 348 (47,180),
stabilizing restraints for the most affected sites S1/S1 , C9/
0
0
3
36 (50,300), 320 (44,440), 284 (42,840), 264 (41,380).
C9 , and C10/C10 (unprimed/primed sites for major and
minor orientation of qbtz). Further information on this
aspect is provided in the deposited Crystallographic Infor-
2
3 2 3
.4. Synthesis of [Cu (qbtz) (m-CN) ] (2)
0
0
0
mation Files. Minor sites (S1 , C9 , C10 , and their hydrogen
atoms) are not shown in the structural drawings (Figs. 1
e3). The cyanide-based compound 2 showed the usual
To a solution of Cu(CH
in 90 mL of acetonitrile was added dropwise and slowly a
3 4 4
CN) ClO (98.2 mg, 0.30 mmol)
Please cite this article in press as: S. Meghdadi, et al., Synthesis, characterization, and X-ray crystal structures of copper(I) halide
and pseudohalide complexes with 2-(2-quinolyl)benzothiazole. Diverse coordination geometries and electrochemical proper-
ties, Comptes Rendus Chimie (2017), http://dx.doi.org/10.1016/j.crci.2017.02.005

S. Meghdadi et al. / C. R. Chimie xxx (2017) 1e8
3
Table 1
Crystallographic parameters, data collection, and refinement details for 1e3.
Empirical formula
C
32
H
20
I
2
Cu
N
2 4
S
2
(1)
C
35
H20Cu
N
3 7
S
2
(2)
34 2 6 4
C H20Cu N S (3)
Formula weight
Temperature (K)
Crystal system
Space group
a (Å)
905.52
100(2)
Triclinic
793.32
100(2)
Triclinic
Pꢁı
12.4075(14)
12.6342(14)
12.7497(14)
114.597(2)
101.217(3)
109.392(3)
1579.9(3)
2
767.88
100(2)
Monoclinic
P2 /n
Pꢁı
1
7.9721(5)
9.3475(5)
10.8772(6)
72.934(3)
77.373(3)
74.257(3)
737.25(7)
1
10.6396(5)
15.3656(8)
18.6910(9)
90
98.1187(9)
90
3025.1(3)
4
1.686
b (Å)
c (Å)
ꢁ
a
b
g
( )
ꢁ
( )
ꢁ
( )
3
v (Å )
z
D
m
3
calc (Mg/m )
2.040
3.71
1.668
2.17
ꢀ
1
(mm
)
1.72
Crystal size (mm)
0.22 ꢂ 0.12 ꢂ 0.09
0.45 ꢂ 0.35 ꢂ 0.10
0.42 ꢂ 0.40 ꢂ 0.25
F(000)
436
796
1552
ꢁ
q
range ( )
2.3e30.0
Multiscan
6178
1.9e26.4
Multiscan
19,374
2.4e30.0
Multiscan
55,478
Absorption correction
Reflections collected
R
int
0.023
0.044
0.023
Data/restraints/parameters
3838/64/206
1.04
6181/153/447
1.08
8820/147/465
1.187
Goodness-of-fit on F2
Final R indices [I > 2
s
(I)]a
R
1
¼ 0.033, wR
2
¼ 0.083
R
1
¼ 0.062, wR
2
¼ 0.115
R
1
¼ 0.030, wR
2
¼ 0.0664
Largest diff. peak and hole (e Åꢀ3)
1.39 and ꢀ0.55
1.29 and ꢀ0.99
0.58 and ꢀ0.48
PjjF
j ꢀ jF
jj=P
jF
o
j; wR
P
P
a
¼ f ½wðFo ꢀ F Þ ꢃ= ½wðF Þ ꢃg1=2.
2
2
2
2
2
R
1
¼
o
c
2
c
o
2 2
consisting of centrosymmetric Cu (m-I) units with the
separation of 2.5855(8) Å between the two Cu(I) centers.
This distance is close to that observed in related complexes
0
like
2.579 Å) [32] or bis(
copper(I) (2.547 Å) [33]. The inversion center is within the
CuI Cu bridge. An analysis with the help of the Cambridge
Structural Database [34] reveals that the CueCu distances
in 76 Cu -I) units with N-bearing coligands vary widely
bis(m-iodido)-bis(2,2 -bipyridine)-di-copper(I)
(
m-iodido)-bis(di-2-pyridylketone)-di-
2
2
(m
2
between 2.51 and 3.27 Å showing a median of 2.68 Å,
whereas the sum of two copper van der Waals radii is
2
.80 Å (see Supplementary data for a table of the 76
structures]. Whether and to what extent a short CueCu
separation of 2.5855 Å within a Cu -I) unit like in 1 in-
2
(m
2
dicates the presence of a stabilizing cuprophilic interaction
remains open to question until suitable quantum-chemical
calculations are available [35]. Although a tetrahedral ge-
ometry might be expected for a four-coordinated copper(I)
center, the coordination sphere around the copper atom in
Fig. 1. View of the molecular structure of [Cu(qbtz)(
probability ellipsoids. Hydrogen atoms and additional sites for the orienta-
tion disordered qbtz ligand are omitted for clarity.
m
-I)]
2
(1) with 50%
1
is distorted by the restricting bite angle of the chelating
qbtz ligand. Disregarding the Cu…Cu interaction, the cop-
per(I) in this complex is in a pseudotetrahedral environ-
ment with a large angular distortion, arising from the low
orientation ambiguity of bridging cyanides, and the cya-
nido groups were all treated as a superposition of pairs of
CN groups with opposed orientations and occupancy fac-
tors adding up to one.
ꢁ
intraligand N2eCu1eN1 chelate angle (79.35 ) that is
ꢁ
much less than the ideal tetrahedral angle of 109.5 . On the
ꢁ
i
contrary, the angles N2eCu1eI1 (117.86 ) and I1eCu1eI1
ꢁ
3
. Results and discussion
.1. Description of the crystal structure of [Cu(qbtz)(
The molecular structure of complex 1 is shown in Fig. 1.
(120.32 ) are much larger than the ideal tetrahedral angle.
The bond distances Cu1eN1, 2.086(3) Å, and Cu1eN2,
2.092(2) Å, are within the expected range and are compa-
rable with those reported for related complexes (2.084(2)
3
2
m-I)] (1)
3
e2.131(3) Å for Cu(qbtz)(PPh )Br/I, [27]). The CueI bond
The crystallographic and refinement data for 1 are sum-
marized in Table 1, and selected bond distances and angles
are listed in Table 2. Complex 1 crystallizes in the triclinic
space group P ꢁı and is a neutral molecular compound
distances (2.5569(4) and 2.6377(4) Å) are similar to those
in related dinuclear copper (I) complexes [32e35]. The qbtz
ꢁ
ligand is twisted by 10.6 about the bond axis C7eC8. In the
crystal lattice, the dinuclear complexes are packed
Please cite this article in press as: S. Meghdadi, et al., Synthesis, characterization, and X-ray crystal structures of copper(I) halide
and pseudohalide complexes with 2-(2-quinolyl)benzothiazole. Diverse coordination geometries and electrochemical proper-
ties, Comptes Rendus Chimie (2017), http://dx.doi.org/10.1016/j.crci.2017.02.005

4
S. Meghdadi et al. / C. R. Chimie xxx (2017) 1e8
Fig. 2. The structure of [Cu
3
(qbtz)
2
(
m-CN)
3
] with 70% probability ellipsoids. Hydrogen atoms and disordered qbtz sites are omitted for clarity. (*) Stands for the
symmetry operation (x, 1 þ y, 1 þ z).
3 2 3
Fig. 3. Crystal packing of the [Cu (qbtz) (m-CN) ] complex.
Table 2
3.2. Description of the crystal structure of [Cu
3 2
(qbtz) (m-
ꢁ
Selected bond lengths (Å) and angles ( ) for 1.
CN) ] (2)
3
Bond lengths
Cu1eN1
Cu1eN2
Cu1eI1
2.086(3)
2.092(2)
2.5569(4)
Cu1eI1i
2.6377(4)
2.5855(8)
4.506(5)
The structure and crystal packing of complex 2 is shown
in Figs. 2 and 3. Crystallographic and refinement data for 2
are summarized in Table 1, and selected bond distances and
angles are listed in Table 4. Complex 2 was synthesized
with the aim of obtaining Cu(CN)(qbtz) with monovalent
i
Cu1eCu1
i
I1eI1
Bond angles
N1eCu1eN2
N1eCu1eI1
i
79.35(12)
118.12(8)
106.67(7)
117.83(7)
107.04(7)
120.32(2)
I1eCu1eCu1
Cu1 eCu1eI1
Cu1eI1eCu1
N1eCu1eCu1
N2eCu1eCu1
61.72(2)
58.61(2)
59.67(2)
139.35(9)
139.52(9)
i
i
i
i
N1eCu1eI1
3 3 2
Cu. The synthesis, however, generated Cu (CN) (qbtz) ,
i
i
N2eCu1eI1
that is, with a 3:3:2 ratio of the constituents. Of the three
crystallographically independent copper atoms Cu(1) and
Cu(2) feature tetrahedral four coordination by each two N
atoms from the chelating qbtz ligand and two CN groups
i
N2eCu1eI1
i
I1eCu1eI1
Symmetry code: (i) 1 ꢀ x, 1 ꢀ y, 1 ꢀ z.
(each bridging two Cu atom). The third copper atom, Cu(3),
approximately perpendicular to (110) by slipped
stacking interactions between adjacent qbtz ligands. The
stacking parameters are listed in Table 3.
p
e
p
displays a quasi-linear two coordination by two CN groups.
This complex crystallizes in the space group P ꢁı and exhibits
a one-dimensional chain structure with a …eCu(qbtz)
p
e
p
Please cite this article in press as: S. Meghdadi, et al., Synthesis, characterization, and X-ray crystal structures of copper(I) halide
and pseudohalide complexes with 2-(2-quinolyl)benzothiazole. Diverse coordination geometries and electrochemical proper-
ties, Comptes Rendus Chimie (2017), http://dx.doi.org/10.1016/j.crci.2017.02.005

S. Meghdadi et al. / C. R. Chimie xxx (2017) 1e8
5
Table 3
transition metal is not invariably either C or N; moreover,
we did not find any literature citation claiming that C must
be bonded to the two-coordinate Cu(I) in a continuous Cu(I)
eCN chain. To assess this situation in 2, we carried out
refinements including CN occupancies. These refinements
yielded occupancy factors of the N-bonded (to Cu3) variety
of 0.48(5), 0.88(5), and 0.85(5) for the cyanido groups N5A
eC5A, N8AeC8A, and N9AeC9A, respectively. It must,
however, be borne in mind that crystals of 2 were not of the
splendid persuasion, and that, therefore, these occupation
numbers should not be taken too literally. But in any case,
there is a perceptible preference for the N bonding to Cu3,
and the exclusively C-bonded CN was clearly disfavored by
R values. A confirmation of preferred N bonding may also
be found in the very similar CCDC refcode MODLOH (see
the detailed discussion in the Supplementary data). The
bond distances to the chelating qbtz ligand,
Cu1eN1 ¼ 2.127(5) Å, Cu1eN2 ¼ 2.160(5) Å, Cu2eN3 ¼
2.128(5) Å, and Cu2eN4 ¼ 2.151(5) Å, are within the ex-
pected range and are in agreement with those reported for
related complexes (2.131(3), 2.126(3), and 2.084(2) Å) [27].
The bond angles around the tetrahedral centers Cu1 and
ꢁ
Aromatic interaction parameters (Å and ) for description of
action in 1e3.
pep inter-
a
b
Cg(I)eCg(J)
d
CgeCg
d
planeeplane
Slippage Symmetry codes
Complex 1
Cg(1)…Cg(3) 3.6514 3.4289, 3.3589
Cg(2)…Cg(3) 3.6622 3.3817, 3.4281
Cg(2)…Cg(5) 3.7511 3.3823, 3.5458
Cg(3)…Cg(3) 3.6816 3.3123, 3.3123 1.607
Cg(3)…Cg(5) 3.6675 3.3094, 3.2972
Cg(4)…Cg(4) 3.6856 3.5995, 3.5995 0.792
Complex 2
Cg(1)…Cg(2) 3.5121 3.4595, 3.4146
Cg(1)…Cg(6) 3.6147 3.2775, 3.3642
Cg(2)…Cg(3) 3.9532 3.4287, 3.3919
Cg(2)…Cg(5) 3.5363 3.3998, 3.3651
Cg(3)…Cg(6) 3.6418 3.3419, 3.3527
Cg(4)…Cg(5) 3.6661 3.3638, 3.3543
Complex 3
Cg(1)…Cg(5) 3.9935 3.6305, 3.6220
Cg(2)…Cg(2) 3.8780 3.4318, 3.4318 1.806
Cg(2)…Cg(4) 3.7353 3.4343, 3.4274
Cg(3)…Cg(5) 3.8035 3.3509, 3.6356
1 ꢀ X, ꢀY, 1 ꢀ Z
1 ꢀ X, ꢀY, 1 ꢀ Z
1 ꢀ X, ꢀY, 1 ꢀ Z
2 ꢀ X, ꢀY, 1 ꢀ Z
2 ꢀ X, ꢀY, 1 ꢀ Z
1 ꢀ X, ꢀY, 1 ꢀ Z
1 ꢀ X, ꢀY, ꢀZ
ꢀ1 þ X, Y, Z
1 ꢀ X, ꢀY, ꢀZ
X, 1 þ Y, Z
ꢀ1 þ X, Y, Z
X, 1 þ Y, Z
1 þ X, Y, Z
1 ꢀ X, ꢀY, ꢀZ
1 ꢀ X, ꢀY, ꢀZ
1 þ X, Y, Z
Complex 1: Cg(1):Cu(1)/N(1)/C(7)/C(8)/N(2); Cg(2): S(1)/C(6)/C(1)/N(1)/
C(7); Cg(3): N(2)/C(8)/C(9)/C(10)/C(11)/C(16); Cg(4): C(1)/C(2)/C(3)/C(4)/
C(5)/C(6); Cg(1): C(11)/C(12)/C(13)/C(14)/C(15)C(16).
Complex 2: Cg(1): S(1)/C(6)/C(1)/N(1)/C(7); Cg(2): N(2)/C(8)/C(9)/C(10)/
C(11)/C(16); Cg(3): C(1)/C(2)/C(3)/C(4)/C(5)/C(6); Cg(4): C(11)/C(12)/
C(13)/C(14)/C(15)/C(16); Cg(5): C(17)/C(18)/C(19)/C(20)/C(21)/C(22);
Cg(6): C(27)/C(28)/C(29)/C(30)/C(31)/C(32).
ꢁ
Cu2 deviate notably from the ideal value of 109.5 , showing
ꢁ
the smallest value of ~77 for the qbtz intraligand angle and
ꢁ
the largest value of ~130 for the CNeCueCN angle,
ꢁ
whereas the rest of the angles vary between 104 and 113
Complex 3: Cg(1): S(1)/C(6)/C(1)/N(1)/C(7); Cg(2): N(2)/C(8)/C(9)/C(10)/
C(11)/C(16); Cg(3): C(1)/C(2)/C(3)/C(4)/C(5)/C(6); Cg(4): C(11)/C(12)/
C(13)/C(14)/C(15)/C(16); Cg(5): C(17)/C(18)/C(19)/C(20)/C(21)/C(22).
(Table 4). The atoms around the Cu3 center are defined by
two cyanide ions with bond lengths of Cu3eN9A ¼ 1.838(5)
Å and Cu3eN8A ¼ 1.843(5) Å. The bond angle around the
a
Centroidecentroid distance.
Perpendicular distance of Cg(I) on ring J and perpendicular distance of
ꢁ
b
Cu3 center is, N9AeCu3eN8A ¼ 179.5(3) , close to the ideal
ꢁ
Cg(J) on ring I.
value of 180 for a linear two coordination [36e39]. Slipped
pe
p
stacking interactions are also observed in this com-
plex. The stacking parameters are listed in Table 3.
pep
Table 4
ꢁ
Selected bond lengths (Å) and angles ( ) for 2.
3
.3. Description of the crystal structure of [Cu(qbtz)(
m-SCN)]
Bond lengths
Cu1eC8A
Cu1eN5A
Cu1eN1
Cu1eN2
Cu3eN9A
Bond angles
N1eCu1eN2
N1eCu1eN5A
N1eCu1eC8A
N2eCu1eN5A
N2eCu1eC8A
C5BeCu1eC8A
N8AeCu3eN9A
(3)
1.912(5)
1.943(5)
2.127(5)
2.160(5)
1.838(5)
Cu2eC9A
Cu2eN5A
Cu2eN3
Cu2eN4
Cu3eN8A
1.902(5)
1.946(5)
2.128(5)
2.151(5)
1.843(5)
The structure of complex 3 is shown in Fig. 4. The
crystallographic and refinement data for 3 are summarized
in Table 1, and selected bond distances and angles are listed
in Table 5. This compound crystallizes in the monoclinic
77.28(19)
104.03(19)
115.2(2)
107.5(2)
109.9(2)
130.2(2)
179.5(3)
176.3(5)
177.8(5)
178.5(5)
N3eCu2eN4
N3eCu2eC5A
N3eCu2eC9A
N4eCu2eC5A
N4eCu2eC9A
C5AeCu2eC9A
77.3(2)
1
space group P2 /n. The asymmetric unit of the structure
105.8(2)
113.1(2)
104.27(19)
111.6(2)
131.4(2)
contains two formula units of Cu(SCN)(qbtz). Each of the
two independent copper atoms, Cu1 and Cu2, is coordi-
nated by two N atoms of a qbtz ligand and by a N atom and
3
a S atom of two different bridging SCN groups. Both CuN S
(
i)
Cu2eC5AeN5A(i)
Cu2eC9AeN9A
Cu3eN9AeC9A
coordination figures are distinctly distorted tetrahedral
showing notable differences between Cu1 and Cu2 in bond
lengths and bond angles as well. Main difference is that the
Cu1eN5AeC5A
Cu1eC8AeN8A
Cu3eN8AeC8A
174.8(5)
178.5(5)
178.8(6)
ꢁ
Symmetry code: (i) x, y ꢀ 1, z ꢀ 1.
bond angle SeCueNSCN for Cu1 is 99.20 , whereas for Cu2 it
ꢁ
is 121.63 (compare also N5eS4
¼
3.229 Å with
i
N6eS3 ¼ 3.676 Å, cf. Fig. 3). The CueNqbtz mean bond
length of 3 is 2.097 Å, comparable to the corresponding
value of <CueNqbtz> ¼ 2.089 Å for 1, but shorter than
<CueNqbtz> ¼ 2.142 Å for 2. The mean bond distance
<CueNSCN> ¼ 1.924 Å is close to the <CueN,C> bond dis-
tance for tetrahedral Cu in 2. CueS bond distances are in
agreement with those reported for related complexes [27].
In the crystal lattice, complex 3 forms continuous zigzag
eCNeCu(qbtz)eCNeCueCNeCu(qbtz)eCNeCu(qbtz)e…
architecture practically identical with that of catena-
0
(
[
tris(m
2
-cyanido)-bis(2,2 -biquinoline)-tri-copper(I))
36,37], which crystallizes in the lattice space group C2/m,
however. The structure of 2 shows the usual orientational
disorder (superposition of quinoline and benzothiazole)
for the qbtz ligand (two independent ligands; popula-
tion parameters for major/minor orientation 0.751/0.249
and 0.705/0.295). The atom coordinating a CN group to a
chains along [ı0 ꢁı ] with
pep stacking interactions between
the qbtz fragments of adjacent chains (Fig. 5). The
pep
Please cite this article in press as: S. Meghdadi, et al., Synthesis, characterization, and X-ray crystal structures of copper(I) halide
and pseudohalide complexes with 2-(2-quinolyl)benzothiazole. Diverse coordination geometries and electrochemical proper-
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6
S. Meghdadi et al. / C. R. Chimie xxx (2017) 1e8
Fig. 4. View of the structure of [Cu(qbtz)(
chain of this structure continues with Cu atoms attached to S3 and N5 .
m
-SCN)] with 50% probability ellipsoids. Hydrogen atoms and disordered qbtz sites are omitted for clarity. The zigzag
i
Table 5
frequencies relative to the free ligand, indicating a decrease
ꢁ
Selected bond lengths (Å) and angles ( ) for 3.
in the C]N bond order because of back bonding from the
*
Bond lengths
Cu1eN5
Cu1eN2
Cu1eN1
Cu1eS4
S3eC33
C33eN5
metal center to the
p
orbital of the ligand and increasing
1.9377(15)
2.0463(15)
2.1298(15)
2.2910(5)
1.658(2)
Cu2eN6
Cu2eN3
Cu2eN4
Cu2eS3
S4eC34
C34eN6
1.9111(15)
2.0759(15)
2.1357(15)
2.2945(5)
1.649(2)
the resonance in the planar coordinated benzothiazole. The
C]Nquinoline and C]Nbenzothiazole stretching vibrations
ꢀ1
i
appear at 1508 and 1587 cm for complex 1, 1509 and
ꢀ
1
ꢀ1
1
590 cm for complex 2, and 1508 and 1588 cm for
ꢀ
1
1.160(2)
1.155(2)
complex 3. The strong absorption band at 2104 cm in
Bond angles
N1eCu1eN2
N1eCu1eN5
N1eCu1eS4
N2eCu1eN5
N2eCu1eS4
N5eCu1eS4
Cu1eN5eC33
Cu1eS4eC34
complex 2 is assigned to the coordinated cyanido ligand
79.28(7)
N3eCu2eN4
N3eCu2eN6
N3eCu2eS3
78.62(6)
ꢀ1
[41]. The strong absorption band at 2094 cm in complex 3
110.31(7)
115.56(4)
132.78(6)
118.58(5)
99.20(5)
120.67(6)
103.71(4)
111.13(6)
113.32(4)
121.63(5)
164.78(15)
94.17(6)
i
is assigned to the thiocyanato CN stretching frequencies
ꢀ
N4eCu2eN6
indicating the coordination of SCN anion with a 1,3-
m-SCN
i
N4eCu2eS3
N6eCu2eS3
bridging modes [41].
i
The UVevis spectra of these compounds were recorded
in DMF solution in the 200e800 nm region and the data are
presented in Section 2. The electronic absorption spectra of
complexes 1e3 show intense bands in the 260e441 nm
161.76(16)
113.81(6)
Cu2eN6eC34
i
i
Cu2eS3 eC33
Symmetry codes: (i) 1/2 þ x, 1/2 ꢀ y, ꢀ1/2 þ z.
region, indicating the presence of intraligand (p/p*) and
10
charge transfer transitions. Copper(I) with d configura-
tion is diamagnetic and no d-d electronic transition is ex-
pected for its complexes.
stacking parameters are listed in Table 3. Such zigzag
chains are present also in the crystal structure of the 2,2 -
0
biquinoline analogue of compound 3, [Cu(biq)(
m-SCN)]
[40], but there is only one kind of Cu that lies together with
SCN on a crystallographic mirror plane bisecting the
chelating biquinoline ligand (orthorhombic space group
3.5. Electrochemical studies
Pnma). The bond lengths in [Cu(biq)(
CueNbiq ¼ 2.107 Å, CueNSCN ¼ 2.931 Å, and CueSSCN
.286 Å, are similar to 3.
m
-SCN)] [40],
The electrochemical behavior of the qtbz ligand and
copper complexes has been studied by cyclic voltammetry
¼
ꢀ1
2
in DMF solution at a scan rate of 100 mVs , with 0.1 M
N(n-Bu) ]PF as the supporting electrolyte at a glassy
carbon working electrode. The approximate concentrations
[
4
6
3
.4. Spectral characterization
ꢀ
4
of the compounds were 5 ꢂ 10 M. Ferrocene (Fc) was
The FT-IR spectral data of the three complexes of copper
are listed in Section 2. The IR spectrum of the free ligand
used as the internal standard, and all redox potentials are
þ/0
referenced to the Fc
couple [29].
ꢀ1
shows two bands at 1558 and 1593 cm characteristic of
2
The voltammogram of [Cu(qbtz)(m-I)] in DMF solution
the C]Nquinoline and C]Nbenzothiazole [27]. In the spectra of
is shown in Fig. 6. The anodic wave at 0.391 V and
the corresponding cathodic wave observed at 0.114 V
complexes the
n(C]N) is generally shifted to lower
Please cite this article in press as: S. Meghdadi, et al., Synthesis, characterization, and X-ray crystal structures of copper(I) halide
and pseudohalide complexes with 2-(2-quinolyl)benzothiazole. Diverse coordination geometries and electrochemical proper-
ties, Comptes Rendus Chimie (2017), http://dx.doi.org/10.1016/j.crci.2017.02.005

S. Meghdadi et al. / C. R. Chimie xxx (2017) 1e8
7
Fig. 5. Crystal packing of the [Cu(qbtz)(m-SCN)] complex.
I/II
(D
E ¼ 277 mV) are attributed to the Cu couple under-
going an irreversible redox process and is in agreement
with the values reported for related Cu(I) complexes [42].
3 2 3
The cyclic voltammogram of [Cu (qbtz) (m-CN) ] in DMF
solution (Fig. 7) shows anodic waves at 0.512 and 0.562 V
and the corresponding cathodic waves at 0.325 and 0.253 V
I/II
and are attributed to the Cu irreversible redox processes
(
D
E ¼ 187 and 309 mV). These observations correlate well
with the existence of two types of copper centers in this
complex.
The voltammogram of [Cu(qbtz)(
Fig. 8. The anodic wave observed at 0.410 and the corre-
sponding cathodic wave at 0.223 V (
m-SCN)] is shown in
D
E ¼ 187 mV) are
I/II
attributed to the irreversible redox processes of Cu
couple, which is in agreement with similar reports on Cu(I)
complexes [43].
The oxidation potential of CuI/II, Epa, in [Cu
CN)
(qbtz)
3
] is more positive than those of 1 and 3 complexes. This
3
2
(m-
2
Fig. 6. Cyclic voltammogram of [Cu(qbtz)(m-I)] in DMF solution at 298 K
ꢀ
1
ꢀ4
(
scan rate ¼ 100 mV s , c ¼ 5 ꢂ 10 M).
Fig. 7. Cyclic voltammogram of [Cu
2
3
(qbtz)
2
(
m-CN)
3
] in DMF solution at
Fig. 8. Cyclic voltammogram of [Cu(qbtz)(m-SCN)] in DMF at 298 K (scan
rate ¼ 100 mV s , c ¼ 5 ꢂ 10 M).
98 K (scan rate ¼ 100 mV sꢀ , c ¼ 5 ꢂ 10 M).
1
ꢀ4
ꢀ1
ꢀ4
Please cite this article in press as: S. Meghdadi, et al., Synthesis, characterization, and X-ray crystal structures of copper(I) halide
and pseudohalide complexes with 2-(2-quinolyl)benzothiazole. Diverse coordination geometries and electrochemical proper-
ties, Comptes Rendus Chimie (2017), http://dx.doi.org/10.1016/j.crci.2017.02.005

8
S. Meghdadi et al. / C. R. Chimie xxx (2017) 1e8
is presumably because of the stronger
p
-acceptor character
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ꢀ
ꢀ
of the CN relative to I and SCN ligands in the corre-
(
ꢀ
ꢀ
ꢀ
sponding copper complexes (I < SCN < CN ), which make
the central metal ion harder to oxidize. The dissociation of
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[
[
[
[
I/II
reduction peaks that overlap with the Cu redox process.
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. Conclusions
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nuclear copper complexes with the bidentate ligand 2-(2-
ꢀ
ꢀ
quinolyl)benzothiazole and the ancillary ligands I , CN ,
ꢀ
[
and SCN . Fully characterized, the single crystal X-ray
structure analysis of these complexes shows that complex 1
is a dinuclear neutral molecular compound consisting of
[
centrosymmetric Cu
generated Cu (CN)
2
(
m
-I) units. For cyanide, the synthesis
2
[
[
[
[
[
[
[
[
[
3
3
(qbtz) . Two of the three crystallo-
2
graphically independent Cu atoms feature tetrahedral four
coordination and the third copper atom features a quasi-
linear two coordination by two CN groups. This complex
exhibits a one-dimensional chain structure. In complex 3
with a zigzag chain structure, the copper ion adopts a
distorted tetrahedral coordination with two N atoms of the
qbtz ligand and two end-on bridging thiocyanato ligands.
These results indicate that the ancillary ligands contribute
substantially to the structural diversity of the complexes.
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6
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Acknowledgments
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Partial support of this work by the Isfahan University of
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The X-ray center of the Vienna University of Technology is
acknowledged for providing access to the single-crystal
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Please cite this article in press as: S. Meghdadi, et al., Synthesis, characterization, and X-ray crystal structures of copper(I) halide
and pseudohalide complexes with 2-(2-quinolyl)benzothiazole. Diverse coordination geometries and electrochemical proper-
ties, Comptes Rendus Chimie (2017), http://dx.doi.org/10.1016/j.crci.2017.02.005