Synthesis, characterization, and crystal structures of two novel ion-pair complexes based on benzene-1,2-dithiolate ligand

Article abstract of DOI:10.1134/S1070328410030103

Two novel ion-pair complexes, [IBzPy][Ni(Bdt)₂] (I) and [IBzDMPy][Ni(Bdt)₂] (II) (IBzPy = 1-(4-iodobenzyl)pyridinium, IBzDMPy = 1-(4-iodobenzyl)-3,5-dimethyl-pyridinium, and Bdt = benzene-1,2-dithiolate), have been synthesized and ch

Full text of DOI:10.1134/S1070328410030103

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2010, Vol. 36, No. 3, pp. 226–231. © Pleiades Publishing, Ltd., 2010.
Synthesis, Characterization, and Crystal Structures of Two Novel
IonꢀPair Complexes Based on Benzeneꢀ1,2ꢀDithiolate Ligand1
G. X. Liua, *, Y. Liua, S. Nishiharab, and X. M. Rena
a Anhui Key Laboratory of Functional Coordination Compounds, School of Chemistry and Chemical Engineering,
Anqing Normal University, Anqing 246003, PR. China
b Department of Physical Science, Graduate School of Science, Osaka Prefecture University Sahai, Osaka 599ꢀ8531, Japan
*Eꢀmail: liugx@live. com
Received June 27, 2009
Abstract—Two novel ionꢀpair complexes, [IBzPy][Ni(Bdt)2] (I) and [IBzDMPy][Ni(Bdt)2] (II) (IBzPy =
1ꢀ(4ꢀiodobenzyl)pyridinium, IBzDMPy = 1ꢀ(4ꢀiodobenzyl)ꢀ3,5ꢀdimethylꢀpyridinium, and Bdt = benzeneꢀ
1,2ꢀdithiolate), have been synthesized and characterized by elemental analysis, IR, cyclic voltammetry, and
Xꢀray singleꢀcrystal structure determination. The crystal structure determination reveals that the central Ni
atoms in complexes I and II are in slightly distorted squareꢀplanar coordination environment. The cyclic volꢀ
tammetric studies show that there are two oxidation peaks for complexes
Ni(IV/III) and Ni(III/II) redox couples.
I and II, which are attributed to
DOI: 10.1134/S1070328410030103
1
INTRODUCTION
[13–17]. The unique physical properties of these comꢀ
plexes not only depend on the specific properties of
the individual components but also are strongly influꢀ
enced by the arrangement of molecules within the
crystal lattice.
Metal complexes of 1,2ꢀdithiolate ligands have
been intensively studied because of their novel properꢀ
ties and applications in the areas of molecular conꢀ
ducting, magnetic materials, nonlinear optics, and
others [1, 2], Over the last decade, a large number of
new dithiolene ligands and resultant complexes have
been prepared to optimize the molecular properties in
an effort to prepare novel and advanced material,
whose molecular arrangement can be sensitively
affected by strong and directional noncovalent interꢀ
actions [3–6]. Although the closedꢀshell cations make
no contribution to the conductivity and magnetism,
their size and shapes play a predominant role in influꢀ
encing the crystal structure and, consequently, in
altering the electronic and magnetic properties. Physꢀ
ical properties of molecular conductors depend on the
molecular alignment in crystals. On the one hand,
unfortunately, the prediction of the molecular alignꢀ
ment within crystal is usually difficult because of the
presence of many local minima of lattice energy
derived from van der Waals interaction, which operꢀ
ates weakly and rather isotropically. On the other
hand, intermolecular interactions, such as hydrogen
Recently, using benzylpyridinium derivatives
(
[RBzPy]+) as the counterꢀcation of [M(Mnt)2]– (M =
Ni, Pd, and Pt; Mnt2– = maleonitriledithiolate), a
series of ionꢀpair complexes with segregated columnar
stacks of cations and anions have been reported [18–
22]. The quasiꢀoneꢀdimensional magnetic nature of
these complexes was attributed to intermolecular πꢀ
orbital interactions within the anionic columns. Furꢀ
thermore, for some complexes, spinꢀPeierlsꢀlike tranꢀ
sition was observed [18, 19]. More presently, we are
devoted to our research interesting on the molecular
magnets selfꢀassemblied from [Ni(Bdt)2]– ion due to
its molecular and electronic structure resembling
[Ni(Mnt)2]– ion, which is expected to obtain new
series of molecular magnets with peculiar magnetic
phase transition via incorporating the benzylpyridinꢀ
ium derivatives into the [Ni(Bdt)2]– spin system.
Herein, we report synthesis, characterization, and
crystal structures of two novel complexes consisting of
[Ni(Bdt)2]– and benzylpyridinium derivatives:
bonds, S···S contacts, and π···π stacking are efficient
organizing forces in supramolecular architecture and
design of new solidꢀstate materials for applications.
Many research groups have succeeded in the strategy
to control organic molecular aggregation by hydrogen
bonding [7–9] and to synthesize organic conductors
[IBzPy][Ni(Bdt)2] (I) and [IBzDMPy][Ni(Bdt)2] (II)
(IBzPy = 1ꢀ(4ꢀiodobenzyl)pyridinium, IBzDMPy =
1ꢀ(4ꢀiodobenzyl)ꢀ3,5ꢀdimethylpyridinium and Bdt =
benzeneꢀ1,2ꢀdithiolate).
assembled by π···π stacking [10–12] or S···S contacts
1
The article is published in the original.
226

SYNTHESIS, CHARACTERIZATION, AND CRYSTAL STRUCTURES
227
EXPERIMENTAL
SAINT program [24], which was also used for the
intensity corrections for the Lorentz and polarization
effects. An empirical absorption correction was
applied using the SADABS program [25]. The strucꢀ
tures were solved by direct methods using the program
SHELXSꢀ97 [26], and all nonꢀhydrogen atoms were
refined anisotropically on F2 by the fullꢀmatrix leastꢀ
squares technique using the SHELXLꢀ97 crystalloꢀ
graphic software package [27]. The hydrogen atoms
were generated geometrically. All calculations were perꢀ
formed on a personal computer with the SHELTXL
crystallographic software package [27]. The details of
the crystal parameters, data collection, and refineꢀ
ments for the complexes are summarized in Table 1.
Selected bond lengths and bond angles with their estiꢀ
mated standard deviations are listed in Table 2.
Atomic coordinates and other structural parameters of
the complexes have been deposited with the Camꢀ
All commercially available chemicals are of reagent
grade and used as received without further purificaꢀ
tion. Benzeneꢀ1,2ꢀdithiol was purchased from TCI
Chemicals; [IBzPy]Br and [IBzDMPy]Br were synꢀ
thesized following the published procedure [23]. Eleꢀ
mental analyses were determined using a Vario EL III
elemental analyzer. IR spectra were recorded in the
4000–400 cm–1 region using KBr pellets and a Nicolet
AVATARꢀ360 spectrometer. Cyclic voltammograms
were recorded on an EG&G potentiostat/galvanostat
model 273 analyzer in a oneꢀcompartment cell. The
glassyꢀcarbon working electrode, Pt counter elecꢀ
trode, and Ag–AgCl reference electrode were used
under Ar atmosphere at 25°C in MeCN solution with
approximately 0.1 M [Bu4N]ClO4 as conducting elecꢀ
trolyte. In the –1.2 to +1.2 V regions a potential scan
rate of 100 mV s–1 was used.
Synthesis of [IBzPy][Ni(Bdt)2] (I). Under argon atꢀ
mosphere at room temperature, benzeneꢀ1,2ꢀdithiol
(284 mg, 2 mmol) was added to a solution of sodium
metal (92 mg, 4 mmol) in 25 ml of absolute methanol. A
bridge Crystallographic Data Center (nos. 695404 (I)
and 695405 (II); deposit@ccdc.cam.ac.uk).
RESULTS AND DISCUSSION
solution of NiCl2 ⋅ 6H2O (240 mg, 1 mmol) in methanol
The Xꢀray structural analysis of
I reveals that the
was added, resulting in the formation of a muddy redꢀ
brown color. Following this, [IBzPy]Br (752 mg, 2 mmol)
was added, and the mixture allowed to stand with stirring
for 1 h and then stirred for 24 h in air. The color of the
mixture gradually turned green, indicating oxidation
from a dianionic species to the more stable monoanionic
form. The precipitate was washed with absolute methaꢀ
nol and ether and then dried. The crude product was reꢀ
crystallized twice from methylene chloride to give black
needles in ~68% yield.
asymmetry unit contains a couple of [Ni(Bdt)2]– anion
and [IBzPy]+ cation as depicted in Fig. 1a. The NiꢀS
distances range from 2.1432(16) to 2.1646(16) Å, with
an average of 2.1459(16) Å, and the cisꢀSNiS angles
range from 85.59(6)° to 91.96(6)°; the NiS4 coordinaꢀ
tion thus adopts a slightly distorted squareꢀplanar conꢀ
figuration. Both of the coordinated Bdt2– anions are
closer to the planar geometry compared to other salts
[28, 29], but [Ni(Bdt2)]– anion as a whole is quasiꢀplaꢀ
nar with Ni as the twist center, there exists the dihedral
IR (KBr; ν
, cm–1): 3041 w, 2957 s, 2856 m, 1485 s, 1421 s,
1225 m, 739 m, 667 s.
angle of 10.16° between the planes of the two coordiꢀ
nated Bdt2– ligands. In the [IBzPy]+ cation, the diheꢀ
dral angles of the N(1)C(19)C(16) reference plane are
For C24H19NIS4Ni
73.96
ring, respectively. The phenyl ring and the pyridine
ring make a dihedral angle of 89.20
As illustrated in Fig. 2, in the crystal of
° for the phenyl ring and 34.11° for the pyridine
anal. calcd., %: C, 45.36;
H, 3.01;
H, 3.07;
N, 2.20.
N, 2.18.
°.
Found, %:
C, 45.33;
I, the anions
and cations are more or less parallel to each other. The
dihedral angle between the pyridine ring of the cation
and the plane of the anion is 2.1°. The interplanar disꢀ
tance between the plane through the anion and the
plane through the cation, lying between two anions, is
about 3.652 Å, and that between the cation and the
anion is about 3.720 Å, which are close enough to conꢀ
Synthesis of [IBzDMPy][Ni(Bdt)2] (II). The syntheꢀ
sis of complex II followed the similar procedure as for
complex I except using [IBzDMPy]Br instead of
[IBzPy]Br. The yield was 57%.
IR (KBr; ν
, cm–1): 3030 w, 2923 m, 1631 m, 1589 w,
1498 s, 1417 s, 1402 w, 1292 s, 1235 m, 1081 m, 1005 m,
928 w, 746 s, 730 s, 674 m.
clude that the cations do have some
action with the acceptor anionic molecules. This
means that two interactions of different strength
exist in a crystal. Moreover, C–H···S intermolecular
contacts between the anion and the cation in are furꢀ
ther consolidate the structure. The most prominent
Xꢀray diffraction analysis. Singleꢀcrystal data for general structural features of the complex are the comꢀ
complexes
and II were obtained on a Bruker Smart pletely segregated stacked columns of [Ni(Bdt)2]–
Apex II CCD with graphiteꢀmonochromated MoKα
anions and [IBzPy]+ cations, as revealed by the projecꢀ
radiation ( = 0.71073 Å) at 296(2) K using the scan tion along the crystallographic axis shown in Fig. 3a.
technique. The data were integrated by using the The Ni···Ni distances is 6.199 Å within the column.
πꢀstacking interꢀ
For C26H23NIS4Ni
π–π
anal. calcd, %: C, 47.08;
Found, %: C, 47.05;
H, 3.49;
H, 3.52;
N, 2.11.
N, 2.09.
I
I
a
λ
ω
x
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2010

228
LIU et al.
Table 1. Crystallographic parameters and a summary of data Table 2. Selected bond lengths and angles in structures
I
and II
collection and refinement for structures
I
and II
Bond
d, Å
Bond
d, Å
Value
Parameter
I
I
II
Ni(1)–S(1)
Ni(1)–S(3)
2.1646(16) Ni(1)–S(2)
2.1554(16) Ni(1)–S(4)
II
2.1432(16)
2.1566(16)
M
635.25
0.20
Monoclinic
21/
663.30
Size, mm
Crystal system
0.36
×
×
0.04 0.26
×
0.12 × 0.10
Triclinic
Space group
P
c
P
1
Ni(1)–S(1)
Ni(2)–S(3)
2.1410(17) Ni(1)–S(2)
2.1363(17) Ni(2)–S(4)
2.1466(16)
2.1597(18)
a
, Å
, Å
, Å
, deg
16.073(4)
8.540(2)
17.776(5)
7.4020(12)
12.624(2)
14.290(2)
91.285(2)
92.270(2)
98.459(2)
1319.2(4)
2
b
Angle
ω
, deg
Angle
ω, deg
c
α
I
β, deg
92.327(3)
S(1)Ni(1)S(2)
S(1)Ni(1)S(4)
91.75(6)
88.97(6)
S(1)Ni(1)S(3) 177.39(7)
γ,
deg
V
, Å3
2438.0(11)
4
S(2)Ni(1)S(3)
S(3)Ni(1)S(4)
87.59(6)
91.96(6)
Z
S(2)Ni(1)S(4) 173.70(7)
ρcalcd, mg m–3
(000)
, deg
1.731
1.670
II
F
1260
662
S(1)Ni(1)S(2)
92.26(6)
S(3)Ni(2)S(4)
91.74(7)
θ
2.29–25.00
11514
4215
1.63–25.05
6488
Reflections collected
asymmetric unit of II contains two different, indepenꢀ
dent halves of centrosymmetric [Ni(Bdt)2]– anions and
one [IBzDMPy]+ cation. The nickel atoms are each
surrounded by four sulfur atoms in squareꢀplanar
geometry. As for the Ni(1)ꢀcontaining unit, the Ni(1)ꢀ
S(1) and Ni(1)ꢀS(2) distances are 2.1410(17) and
2.1466(16) Å, respectively (Table 2). The values are in
agreement with the analogous [Ni(Bdt)2]– complex
reported [28, 29]. The SꢀNiꢀS bond angle within
Independent reflections
4522
int = 0.0240)
(
R
int = 0.0695)
(
R
Parameters
280
303
Goodnessꢀofꢀfit on F 2
1.020
1.087
Final
R
indices (
I
> 2
σ
(
I
))
R
1 = 0.0799,
wR2 = 0.2015
R
1 = 0.0539,
wR2 = 0.1833
R
indices (all data)
R
1 = 0.0913,
wR2 = 0.2164
R1 = 0.0712,
wR2 = 0.2117
the fiveꢀmember ring is 92.26(6)°, which is slightly
larger than that observed in the complex with subꢀ
stituent groups on benzene rings [28, 29]. There
Large diff. peak and hole, 1.879/–1.563
1.157/–1.032
Å–3
exists
a
dihedral angle of 3.08
°
between
e
C(1)C(2)C(3)C(4)C(5)C(6)S(1)S(2) (C6S2) and the
Ni(1)S(1)S(2) planes, so the anion adopts an envelope
2
2
2 1/2
R
w
=
S||
F
|
–
2
|
F
||
/
S|
F
|. wR
=
|S
w
(
|
F
|
–
|
F
|
)|/S|
w
(F ) |
o
,
1
o
c
o
2
o
c
(F2o + 2F2c) /3.
conformation and the Ni(1) atom deviates by 0.092
from the C6S2 plane. In Ni(2)ꢀcontaining unit, the
Ni S bonds cover the range from 2.1363(17) to
2.1597(18) Å and the SNiS bond angle within the
five member ring is 91.74(7) , which is in agreement
with that of the Ni(1)ꢀcontaining unit. The Ni(2)
atom deviates by 0.025 from the
Å
2
2
= 1/[s (Fo) + (aP) + bP].
P
=
⎯
The nearest Ni···Ni contact between [Ni(Dmit)2]– colꢀ
umns is much longer at 8.540 Å and is longer than the
Ni···Ni distance within the [Ni(Bdt)2]– column.
°
Å
C(7)C(8)C(9)C(10)C(11)C(12)S(3)S(4) plane and
the angle between C6S2 and the Ni(2)S(3)S(4) planes
It is interesting to find that, when [IBzDMPy]+
with two methyl groups in the pyridine ring was introꢀ
duced as countercation, complex II with different
is 1.21
nearly perpendicular to each other with a dihedral
. In the [IBzDMPy]+, the dihedral
°. The Ni(1)C6S2 and Ni(2)C6S2 planes are
structures was obtained. As shown in Fig. 1b, the angle of 89.36
°
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
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SYNTHESIS, CHARACTERIZATION, AND CRYSTAL STRUCTURES
229
(a)
C(11)
C(12)
S(4)
C(10)
S(1)
C(2)
C(1)
C(9)
Ni(1)
C(3)
C(7)
S(3)
C(8)
C(6)
C(4)
S(2)
C(17)
C(16)
C(5)
C(18)
C(19)
N(1)
C(24)
I(1)
C(13)
C(20)
C(21)
C(15)
C(14)
C(23)
C(22)
C(9A)
C(8A)
(b)
C(10
A
)
C(7A
S(3A)
)
C(11A)
C(12A)
S(4)
C(11)
C(10)
S(4A)
Ni(2)
C(12)
S(3)
C(7)
C(8)
C(17)
C(19)
C(24)
C(9)
C(5A
)
S(2A
)
S(1)
C(2)
C(18)
C(13)
C(1)
C(6)
C(4A)
C(26)
C(16)
N(1)
C(3)
C(23)
C(6A)
C(22)
C(20)
C(4)
C(15)
I(1)
C(21)
C(14)
Ni(1)
)
C(1A)
C(2A)
C(3A)
C(5)
C(25)
S(2)
S(1A
Fig. 1. ORTEP representation of I (a) and II (b) showing local coordination environment of Ni(III) with thermal ellipsoids at
30% probability. Hydrogen atoms are omitted for clarity.
angles of the N(1)C(19)C(16) reference plane are
The cyclic voltammograms of
I
and II display two
48.52
ring, respectively. The phenyl ring and the pyridine
ring make a dihedral angle of 85.97
° for the phenyl ring and 70.05° for the pyridine
quasiꢀreversible oneꢀelectron redox processes. As an
example, Fig. 4 shows the CV curve of , and the halfꢀ
wave potentials versus Ag/AgCl are 268 mV
=111 mV) and –311 mV ( = 91 mV), respecꢀ
tively. The former wave is assigned to the redox couple
of [Ni(Bdt)2]–/0, and the later is attributed to the redox
couple of [Ni(Bdt)2]–/2–. For II, the corresponding
I
°.
(
ΔE
ΔE
The molecule packings of two anionic units in II
differ from each other (Fig. 1b). The Ni(1)ꢀcontaining
units stack in faceꢀtoꢀface fashion with an alternating
arrangement of the [Ni(Bdt)2]– anion and [IBzDꢀ
MPy]+ cation, so that the pyridine ring moiety of the
cation lies above the phenyl ring moiety of the correꢀ
sponding Ni(2)ꢀcontaining units and vice versa, and
the shortest distance between adjacent Ni3+ ions is
7.402 Å. Conversely, the Ni(1)ꢀcontaining units stack
in sideꢀbyꢀside fashion in which the anions with uniꢀ
form spaced arrangements form oneꢀdimensional
halfꢀwave potentials versus Ag/AgCl are 272 mV (ΔE =
(1D) chain along the
x axis. The shortest distance
between adjacent Ni3+ ions is 7.402 Å too. Between the
most adjacent Ni(1)ꢀcontaining and Ni(2)ꢀcontaining
units, a Ni···Ni distance of 9.427 Å is found. The Niꢀ
containing anion and [IBzDMPy]+ cation are held
together via abnormal C(19)–H(19
Hꢀbonding interactions and I(1)···S(3 (1 +
A
)···S (
x
, –1 +
y, z)
x, 1 – y, z)
weak interactions to consolidate the structure
(Fig. 3b).
Fig. 2. CꢀC–H···S intermolecular contacts between the
anion and the cation in
I.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
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230
LIU et al.
(a)
20
10
0
x
0
z
–10
–20
y
800
400
0
–400
, mV
–800
–1200
E
Fig. 4. Cyclic voltammogram of [IBzPy][Ni(Bdt) ] in
2
CH CN
.
3
(b)
ACKNOWLEDGMENTS
This work was supported by the National Natural
Science Foundation of China (no. 20971004), the
Natural Science Foundation for Outstanding Scholars
of Anhui Province, China (Grant no. 044ꢀJꢀ04011),
and the Natural Science Foundation of Education
Commission of Anhui Province, China (no.
KJ2008B004).
x
0
z
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