Synthesis, crystal structure, and magnetic property of a new nickel(III) complex constructed from 1,2-benezedithiolate

Article abstract of DOI:10.1080/15533174.2010.492554

The new complex, [IBzPyCH₃][Ni(bdt)₂] (1), has been synthesized and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction, in which [IBzPyCH₃]⁺ = 1-(4-iodobenzyl)-3-methylpyridinium and bdt^2- = 1,2-benzene- dithiolate. The X-ray structure analysis shows that the anions are centrosymmetric, the two nonequivalent anions form different uniform-spaced stacking pattern and the weak H-bonding interactions of C-H...S were observed in 1. The temperature dependence of magnetic susceptibilities of 1 indicates ferromagnetic behavior in the antiferromagnetic exchange system, which may arise from spin-canting. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/15533174.2010.492554

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 40:416–420, 2010
Copyright © Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2010.492554
Synthesis, Crystal Structure, and Magnetic Property
of a New Nickel(III) Complex Constructed from
1,2-Benezedithiolate
Guang-Xiang Liu,1 Ying Liu,1 Sadafumi Nishihara,2 and Xiao-Ming Ren1
1Anhui Key Laboratory of Functional Coordination Compounds, School of Chemistry and Chemical
Engineering, Anqing Normal University, Anqing, P. R. China
2Department of Physical Science, Graduate School of Science, Osaka Prefecture University, Sakai,
Osaka, Japan
columnar stack structures, in which intermolecular dz2or π or-
bital interactions result in 1-D electronic nature.[6−9] Usually,
the topology and size of the counter cation in M(mnt)−2 com-
plexes may play an important role in controlling the stacking
pattern of anions and cations, which further influence the phys-
ical properties of these complexes.
The new complex, [IBzPyCH3][Ni(bdt)2] (1), has been synthe-
sized and characterized by elemental analysis, IR spectroscopy
and single-crystal X-ray diffraction, in which [IBzPyCH3]+
=
1-(4-iodobenzyl)-3-methylpyridinium and bdt2− = 1,2-benzene-
dithiolate. The X-ray structure analysis shows that the anions
are centrosymmetric, the two nonequivalent anions form different
uniform-spaced stacking pattern and the weak H-bonding interac-
tions of C-H· · ·S were observed in 1. The temperature dependence
of magnetic susceptibilities of 1 indicates ferromagnetic behavior
in the antiferromagnetic exchange system, which may arise from
spin-canting.
In our previous research, using benzylpyridinium derivatives
([RBzPy]+) as the counter-cation of [M(mnt)2]− (M = Ni, Pd
and Pt), a series of ion-pair compounds with segregated colum-
nar stacks of cations and anions have been prepared.[4,5] The
quasi-one-dimensional magnetic nature of these complexes was
attributed to intermolecular π-orbital interactions within the an-
ionic columns. Furthermore, for some complexes, spin-Peierls-
like transition was observed.[5] More recently, we devoted our
research interest on the molecular magnets self-assembly from
[Ni(bdt)2]− ion due to its molecular and electronic structure
resemble [Ni(mnt)2]− ion, which is expected to obtain new se-
ries of molecular magnets with peculiar magnetic phase tran-
sition via incorporating the benzylpyridinium derivatives into
[Ni(bdt)2]− spin system. Herein, we report synthesis, crystal
structure, and magnetic properties of a novel complex consist-
ing of [Ni(bdt)2]− and 1-(4-iodobenzyl)-3-methyl-pyridinium.
Keywords crystal structure, magnetism, nickel(III) thiolate complex,
spin-canting
INTRODUCTION
In the past decades, one-dimensional (1-D) compounds
have been attracting widespread attention because they show
novel physical properties such as Peierls transition, spin-Peierls
transition, charge density wave (CDW) states, spin density
wave (SDW) states, molecular bistability, molecular magnetic
nanowire properties, etc.[1−5] In addition, 1-D compounds have
also stimulated theoretical investigations. One of the most stud-
ied classes of 1-D transition metal complexes is the complexes
containing M(mnt)−2 (M = Ni(III), Pd(III) or Pt(III)) ions. In
these compounds, the constituent planar anions M(mnt)−2 form
EXPERIMENTAL
Materials and Measurements
All commercially available chemicals are of reagent grade
and used as received without further purification. Solvents were
purified by standard methods prior to use. 1-(4-iodobenzyl)-
3-methylpyridinium bromide ([IBzPyCH3]Br) was synthesized
following the published procedure.[6] Elemental analyses (C, H
and N) were performed on a Vario EL III elemental analyzer.
The IR spectrum as a KBr disk was recorded on a Nicolet
Avatar 360 FT-IR spectrometer. Magnetic susceptibility data
on polycrystalline sample were collected over the temperature
range of 2–300 K using a MPMS7 magnetometer (Quantum
Received 27 September 2009; accepted 17 April 2010.
This work was supported by the National Natural Science Founda-
tion of China (No. 20971004), the Key Project of Chinese Ministry of
Education (No. 210102), and the Natural Science Foundation of Edu-
cational Commission of Anhui Province of China (No. KJ2010A229).
Address correspondence to Guang-Xiang Liu, School of Chem-
istry and Chemical Engineering, Anqing Normal University, Anqing
246003, P. R. China. E-mail: liugx@live.com
416

NOVEL ION-PAIR COMPLEX
417
S, 19.75. Found: C, 46.22; H, 3.29; N, 2.18; S, 19.77. IR (cm−1):
3055 (w), 2953 (s), 2846 (m), 1484 (s), 1423 (s), 1227 (m), 737
(m), 665 (s).
TABLE 1
Crystal data for (1)
Complex
(1)
Formula
FW
C25H21INS4Ni
649.28
DATA COLLECTION, STRUCTURAL DETERMINATION,
AND REFINEMENT
Size (mm−3
)
0.26 × 0.20 × 0.12
Crystal Structure Determination
Crystal system
Space group
Triclinic
The crystallographic data collections for complex 1 were
carried out on a Bruker Smart Apex II CCD with graphite-
P-1
˚
a (A)
7.3222(14)
12.267(2)
14.628(3)
98.425(2)
98.466(2)
96.216(3)
1274.2(4)
2
296(2)
0.71073
1.692
646
˚
monochromated Mo-Kα radiation (λ = 0.71073 A) at 296(2)
˚
b (A)
K using the ω-scan technique. The data were integrated by
using the SAINT program,[8] which also did the intensi-
ties corrected for Lorentz and polarization effect. An empir-
ical absorption correction was applied using the SADABS
program.[9] The structures were solved by direct methods us-
ing the program SHELXS-97and all non-hydrogen atoms were
refined anisotropically on F2 by the full-matrix least-squares
technique with SHELXL-97.[10,11] The hydrogen atoms were
generated geometrically. The details of the crystal parame-
ters, data collection and refinement for 1 are summarized in
Table 1. Selected bond lengths and bong angles for complex
1 are listed in Table 2. Crystallographic data for the two com-
plexes have been deposited with Crystallographic Data Center
(CCDC 668713).
˚
c (A)
α(◦)
β (◦)
γ (◦)
3
˚
Volume(A )
Z
T (K)
˚
Wavelength (A)
Dcalcd (mg·m−3
)
F(000)
θ (◦)
1.43–25.00
6282
4392 [Rint = 0.0695]
4392/293
1.091
Reflections collected
Independent reflections
Data/parameters
Goodness of fit on F2
Final R indices [I > 2σ
(I)]
RESULTS AND DISCUSSION
R1 = 0.0559, wR2 = 0.1776
Structure Description of the Complex
R indices (all data)
Large −di3ff. peak and hole
R1 = 0.0694, wR2 = 0.1957
The X-ray crystallographic structure analysis of 1 reveals
that it crystallizes in triclinic with space group P-1. As shown
in Figure 1, the asymmetric unit of 1 contains two different, inde-
pendent halves of centrosymmetric [Ni(bdt)2]− anions, and one
[IBzPyCH3]+ cation. The nickel atoms are each surrounded by
four sulfur atoms in square-planar geometry, which is markedly
different from a spiro compound Si(bdt).[212] As for the Ni(1)-
containing unit, the Ni(1)-S(1) and Ni(1)-S(2) distances are
1.524 and –1.913
˚
(e A
)
2
2
R1| = |ꢀ||Fo| − |Fc||/ꢀ|Fo|. wR2 = |ꢀw(|Fo| − |Fc| )|/
ꢀ|w(Fo)2|1/2, w = 1/[σ2(Fo2)+(aP)2+bP]. P = (Fo2+ 2Fc2)/3.
Design) in an external field of 2000 Oe, and the diamagnetism
was corrected by Pascal constants.[7]
˚
2.1470(16) and 2.1562(16) A, respectively. The values are in
agreement with the analogous [Ni(bdt)2]− complex reported.[13]
Synthesis of [IBzPyCH3][Ni(bdt)2] (1)
Under argon atmosphere at room temperature, benzene-1,2-
dithiol (284 mg, 2 mmol) was added to a solution of sodium
metal (92 mg, 4 mmol) in 25 ml of absolute methanol. A solu-
tion of NiCl2·6H2O (237 mg, 1 mmol) in methanol was added,
resulting in the formation of a muddy red-brown color. Follow-
ing this, [IBzPyCH3]Br (780 mg, 2 mmol) was added and the
mixture was allowed to stand with stirring for 1 h, and then
stirred for 24 h with the presence of atmosphere. 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 methanol and ether and
then dried. The crude product was recrystallized twice from
methylene chloride to give dark green block crystals in ca. 77%
yield. Anal. calcd for C25H21INS4Ni: C, 46.24; H, 3.26; N, 2.16;
TABLE 2
◦
˚
Selected bond lengths (A) and bond angles ( ) for (1)
Ni(1)-S(1)
2.1470(16)
Ni(1)-S(2)
2.1562(16)
Ni(2)-S(3)
S(1)-C(1)
C(1)-C(6)
S(4)-C(12)
2.1504(17)
1.747(6)
1.390(8)
1.749(7)
Ni(2)-S(4)
S(2)-C(6)
S(3)-C(7)
C(7)-C(12)
2.1447(15)
1.745(6)
1.732(6)
1.381(9)
S(1)-Ni(1)-S(2) 91.59(6) S(1)-Ni(1)-S(2)#1 88.41(6)
S(4)-Ni(2)-S(3) 91.79(6) S(4)#2-Ni(2)-S(3) 88.21(6)
C(1)-S(1)-Ni(1) 104.7(2)
C(6)-S(2)-Ni(1)
105.1(2)
C(7)-S(3)-Ni(2) 105.5(2) C(12)-S(4)-Ni(2) 104.1(2)
Symmetry codes: #1 -x+1, -y, -z+1; #2 -x+1, -y+2, -z+2.

418
G.-X. LIU ET AL.
FIG. 1. ORTEP representation of complex (1) with 30% thermal ellipsoids. Hydrogen atoms have been omitted for clarity.
FIG. 2. The molecule packing diagram of two different Ni(bdt)−2 anions with the Ni· · ·Ni distances of 7.322 A.
˚

NOVEL ION-PAIR COMPLEX
419
The S-Ni-S bond angle within the five-member ring is 91.59(6)◦,
which is slightly larger than that observed in complex with sub-
stituent groups on benzene rings.[14] There exists a dihedral an-
gle of 6.91◦ between C(1)C(2)C(3)C(4)C(5)C(6)S(1)S(2) (abbr.
C6S2) and the Ni(1)S(1)S(2) planes, so the anion adopts an en-
ing pattern of 1 is different from that of the reported,[15] since
variation of the substituents of pyridine ring would be ex-
pected to affect the conformation of the cation in this series of
complexes.
˚
velope conformation, and the Ni(1) atom deviates 0.181 A from
Magnetic Property
C6S2 plane. In Ni(2)-containing unit, the Ni-S bonds cover the
The temperature dependence of the magnetic susceptibility
for the powdered sample of 1 was measured in the range of 2-
300 K in the form of the χMT versus T curve, where χM is the
molar magnetic susceptibility (Figure 4). Its magnetic behavior
may be divided into three parts on their temperature dependence.
˚
range from 2.1447(15) to 2.1504(17) A and the S-Ni-S bond
angle within the five-member ring is 91.79(6)◦ which is in
agreement with that of Ni(1)-containing unit. The Ni(2) atom
˚
deviates 0.013 A from 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
is 1.24◦. The Ni(1)C6S2 and Ni(2)C6S2 planes are nearly per-
pendicular to each other with the dihedral angle of 74.74◦.
In the 1-(4-iodobenzyl)-3-methylpyridinium cation, the dihe-
dral angles of the N(1)-C(19)-C(16) reference plane are 42.85◦
for phenyl ring, 63.19◦ for pyridine ring, respectively. The
phenyl ring and the pyridine ring make a dihedral angle of
86.94◦.
The value of χMT at 300 K is estimated at 0.368 emu K mol−1
,
and is smaller than that of spin-only of one S = 1/2 spin per for-
mula unit. The χMT values decrease continuously upon cooling
until 194 K, indicating the presence of antiferromagnetic ex-
change between metal centers. Then, the χMT values increase
gradually between 194 and 18 K and reaches a maximum at
approximately 18 K (χMT = 0.406 emu K mol−1) exhibiting
ferromagnetic coupling behavior. The magnetic behavior in the
temperature range 300-18 K may arise from spin-canting mech-
anism. Spin-canting arises through a Dzyaloshinsk-Moriya in-
teraction, which minimizes the coupling energy when two spins
are perpendicular to one another. Furthermore, it should be ful-
filled when canting spins in the solid state are not related by a
center of inversion.[16] Based on its crystal structure, it is worth
noting that the two nonequivalent Ni(III) ions do not relate to
each other through an inversion center, and thus there may exist
incomplete cancellation of spins between Ni(1)-containing and
Ni(2)-containing units. When the temperature is below 18 K, the
χMT values decrease quickly and drop to 0.296 emu K mol−1
at extremely low temperatures and this phenomenon may ori-
gin from magnetization saturation effect.[17] The data over the
entire temperature are best fit by the Bonner-Fisher model for
The molecule packing of two anion units in 1 is different from
each other (Figure 2). The Ni(1)-containing units stack in face to
face fashion with an alternating arrangement of [Ni(bdt)2]− an-
ion and [IBzPyCH3]+ cation such that the pyridine ring moiety
of cation lie above the phenyl ring moiety of the corresponding
Ni(1)-containing units and vice versa and the shortest distance
˚
between adjacent Ni(III) ions is 7.322 A. Conversely, the Ni(2)-
containing units stack in side by side fashion, in which the
anions with uniform spaced arrangements to form one dimen-
sional (1-D) chain along a-axis. The shortest distance between
˚
adjacent Ni(III) ions is 7.322 A, too. Between the most adjacent
Ni(1)-containing and Ni(2)-containing units, a Ni···Ni distance
+
˚
of 7.314 A is found. Ni-containing anion and [IBzPyCH3]
cation are held together via non-normal C(19)-H(19B)· · ·S(2)(-
1+x, 1+y, z) and C(20)-H(20)· · ·S(4)(-x, 2-y, 2-z) H-bonding
interactions to consolidate the structure (Figure 3). The stack-
0.40
0.16
0.35
0.30
0.12
0.25
0.08
0.20
0.15
0.04
0.10
0
50
100
150
200
250
300
Temperature / K
0.00
0
50
100
150
200
250
300
Temperature / K
FIG. 4. Temperature independence of the the χM values for complex (1).
The solid line represents the best fit. Inset: temperature dependence of the χMT
values for complex (1).
FIG. 3. The packing diagram of the complex (1) along bc plane. The hydrogen
bonds are indicated by dashed lines.

420
G.-X. LIU ET AL.
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2
ꢀ
ꢁ
Ng2µ2B
=
kBT
0.25 + 0.74975Z + 0.075235Z
2
χm
2
3
1 + 0.9331Z + 0.172135Z + 0.757825Z
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In this contribution, we fabricated a new ion-pair complex
containing the [Ni(bdt)2]− unit. Two nonequivalent anions are
stacked in different fashion, i.e., face to face or side by side
in the complex. To our best knowledge, this structural motif is
unprecedented in the chemistry of [M(bdt)2]− complexes and is
remarkably different from the corresponding [M(mnt)]− com-
plexes. The magnetic properties of the complex show that the
primary exchange process involves antiferromagnetic coupling
between nickel centers with a canting of the spins, that is to say,
the weak ferromagnetism at a low temperature may be due to a
consequence of canted spin antiferromagnetism.

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