Syntheses, crystal structures, and magnetic properties for two spin-ladder complexes based on bis(2-thioxo-1,3-dithiole-4,5-dithiolato)nickelate monoanion building block

Article abstract of DOI:10.1134/S1070328412120068

Two isostructural complexes based on bis(2-thioxo-1,3-dithiole-4,5- dithiolato)nickelate monoanion ([Ni(Dmit)₂]^-) building block, (C₁₉H₁₁NNiF₃S₁₀ (I) and C₁₈H₁₀N₂F₃NiS₁₀ (II)), have been synthesized and characterized structurally and magnetically. Two complexes crystallize in monoclinic space group P1 with very similar cell parameters and packing structures. The planar [Ni(Dmit)₂]^- monoanions form face-to-face π-type dimer, and the neighboring dimers are aligned into a ladder-type arrangement via lateral-to-lateral S.S contacts along x axis in the crystals of I and II. Two complexes exhibit similar magnetic behaviors, and their magnetic susceptibility data can be fitted to a Heisenberg antiferromagnetic two-legged spin ladder formula in high-temperature region and reproduced well by the Troyer expression in low-temperature region. The spin-gap values, obtained, respectively, from the fits of magnetic susceptibility data in high- and low-temperature regions, are closed to each other, indicating the chose magnetic exchange model and the results of fits are reasonable.

Full text of DOI:10.1134/S1070328412120068

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2013, Vol. 39, No. 1, pp. 147–155. © Pleiades Publishing, Ltd., 2013.
Syntheses, Crystal Structures, and Magnetic Properties for Two
SpinꢀLadder Complexes Based on Bis(2ꢀThioxoꢀ1,3ꢀDithioleꢀ4,5ꢀ
Dithiolato)Nickelate Monoanion Building Block1
H. Zhanga, b, B. Caia, H. B. Duanc, *, G. J. Yuana, F. Xuana, and X. M. Rena, d,
*
a Department of Applied Chemistry, College of Science, Nanjing University of Technology, Nanjing, 210009 P.R. China
b Department of Chemistry, Huangshan University, Huangshan, 245041 P.R. China
c School of Biochemical and Environmental Engineering, Nanjing Xiaozhuang College, Nanjing, 210017 P.R. China
d Coordination Chemistry Institute and State Key Laboratory, Nanjing University, Nanjing, 210093 P.R. China
*eꢀmail: duanhaibao4660@163.com; xmren@njut.edu.cn
Received July 12, 2011
Abstract
monoanion ([Ni(Dmit)2]–) building block, (C19H11NNiF3S10
synthesized and characterized structurally and magnetically. Two complexes crystallize in monoclinic space
—
Two isostructural complexes based on bis(2ꢀthioxoꢀ1,3ꢀdithioleꢀ4,5ꢀdithiolato)nickelate
(
I
) and C18H10N2F3NiS10 II)), have been
(
⎯
group
P
1 with very similar cell parameters and packing structures. The planar [Ni(Dmit)2]– monoanions
form faceꢀtoꢀface ꢀtype dimer, and the neighboring dimers are aligned into a ladderꢀtype arrangement via
lateralꢀtoꢀlateral S⋅⋅⋅S contacts along axis in the crystals of and II. Two complexes exhibit similar magnetic
π
x
I
behaviors, and their magnetic susceptibility data can be fitted to a Heisenberg antiferromagnetic twoꢀlegged
spin ladder formula in highꢀtemperature region and reproduced well by the Troyer expression in lowꢀtemperꢀ
ature region. The spinꢀgap values, obtained, respectively, from the fits of magnetic susceptibility data in highꢀ
and lowꢀtemperature regions, are closed to each other, indicating the chose magnetic exchange model and
the results of fits are reasonable.
DOI: 10.1134/S1070328412120068
1
INTRODUCTION
its molecular and electronic structures resemble to
those of [Ni(Mnt)2]– ion. The [Ni(Dmit)2]– ion is also
an excellent building block employed for constructing
molecular magnetic materials apart from its wellꢀ
Bisꢀ1,2ꢀdithiolene complexes of transition metal
have been widely studied due to their novel properties
and applications in the areas of conducting and magꢀ
netic materials, dyes, nonꢀlinear optics, catalysis and known electric conductivity. In comparison with
[Ni(Mnt)2]– complexes, the presence of versatile S⋅⋅⋅
S
others [1–9]. Experimental and theoretical investigaꢀ
tions indicated that these applications arise from the
specific geometries and intermolecular interactions of
bisꢀ1,2ꢀdithiolene complex anions and the materials
properties are hypersensitive to the anions stacking
pattern [1, 2]. In our previous studies, a series of quasiꢀ
oneꢀdimensional (quasiꢀ1D) quantum magnetic
chain systems have been built using bis(maleoniꢀ
triledithiolato)nickelate monoanion [Ni(Mnt)2]– as
the magnetic architecture and benzylpyridinium derivꢀ
ative as the countercation, among them, a novel spinꢀ
Peierlsꢀtype transition (a magnetic transition from
paramagnetic to nonmagnetic phases) below a critical
temperature was observed in some complexes [10–16].
Most recently, we have being devoted our research
to the molecular magnets selfꢀassembled from magꢀ
netic bis(l,3ꢀdithioleꢀ2ꢀthioneꢀ4,5ꢀdithiolate)nickeꢀ
late monoanion ([Ni(Dmit)2]–) architecture owing to
interaction manners in [Ni(Dmit)2]– complexes lead
to adaptable arrangements between the neighboring
[Ni(Ddmit)2]– anions in the crystal, for instance, the
styles of cofacial stack, lateralꢀtoꢀlateral or headꢀtoꢀ
tail
S⋅⋅⋅S
contacts between the neighboring
[Ni(Dmit)2]– anions, which could give rise to 1D
chain [17], 1D ladder [18, 19] or 2D layer [20, 21] arꢀ
rangements of [Ni(Dmit)2]– anions, are generally obꢀ
served. Diverse stacking structures of [Ni(Dmit)2]–
anions maybe give differently physical properties of
materials. Working along these lines, two complexes
with 1D laddered arrangements of [Ni(Dmit)2]– anꢀ
ions have been achieved via introducing the benzylpyꢀ
ridinium derivatives into [Ni(Dmit)2]– spin systems. It
is fascinating that one complex (with lateralꢀtoꢀlateral
S
⋅⋅⋅S contacts between the neighboring [Ni(Dmit)2]–
anions within the ladderedꢀtype chain) exhibits longꢀ
1
The article is published in the original.
147

148
ZHANG et al.
, cm–1): 3049 w (
ν
(C–H)
(C–H)
range antiferromagnetic (AFM) ordering, whereas anꢀ
other complex (with headꢀtoꢀtail S⋅⋅⋅S contacts beꢀ
tween the neighboring [Ni(Dmit)2]– anions within a
ladderedꢀtype chain) shows a spinꢀPeierlsꢀtype magꢀ
netic transition [22]. Furthermore, three polymorphs
with 2D layered arrangements of [Ni(Dmit)2]– anions
were obtained, replacing benzylpyridinium derivative
by a benzylquinolinium derivative, and these polyꢀ
morphs show unusual behavior of spin bistability with
IR spectrum (KBr disc;
of phenyl or pyridyl ring); 2974 w and 2924 w (
of –CH2– group); 1613 sh, 1485, 1444, 1417 and 1385
(C=C) or (C=N) of the phenyl or pyridyl ring);
1349 s (
(C=C) of Dmit2– ligand); 1159 s and 1117 s
(symmetric and asymmetric C–F stretch of –CF3
group); 1061 s (
(C=S) of Dmit2– ligand).
ν
ν
(ν
ν
ν
ν
For C18H10N2F3NiS10 (II
anal. calcd., %: C, 31.30;
Found: C, 31.09;
)
bigger hysteresis loop (∼50 K) [23].
N, 4.06;
N, 3.95;
H, 1.46.
H, 1.52.
In order to gain an insight into the correlations beꢀ
tween the molecular structure of the countercation
and the arrangement of [Ni(Dmit)2]– anion as well as
the correlations between the magnetic behavior of the
molecular solid and the arrangement of [Ni(Dmit)2]–
anion, we are systematically exploring the series of
[Ni(Dmit)2]– complexes. Herein, we present the inꢀ
vestigations of the crystal structures and magnetic
properties for two new spinꢀladder complexes of
[Ni(Dmit)2]– monoanion with 1ꢀNꢀ(4'ꢀtrifluoromeꢀ
IR spectrum (KBr disc;
of phenyl or pyridyl ring); 2967 w, 2925 w (
–CH2– group); 1604 sh, 1440, and 1385 s (
(C=N) of the phenyl or pyridyl ring); 1350 s
(C=C) of Dmit2– ligand); 1161 s and 1124 s (symꢀ
metric and asymmetric C–F stretch of –CF3 group);
1061 s (
(C=S) of Dmit2– ligand).
ν
, cm–1): 3012 w (
(C–H) of
(C=C) or
ν
(C–H)
ν
ν
ν
(ν
ν
thylbenzyl)pyridinium and 1ꢀNꢀ(4'ꢀtrifluoromethylꢀ
benzyl)pyrazinium, respectively, (C19H11NNiF3S10 (I)
and C18H10N2F3NiS10 (II)).
Physical measurements. Elemental analyses for C,
H, and N were carried out with a PerkinElmer 240 anꢀ
alytical instrument. IR spectra (KBr pellets) were colꢀ
lected by a Fourier Transform Infrared spectrophoꢀ
tometer (170SX) in the range of 4000–400 cm–1.
EXPERIMENTAL
Magnetic susceptibilities of I and II were collected on
Chemicals, reagents, and materials. All chemicals
and solvents were reagent grade and used as received.
Tetrabutylammonium bis(1,3ꢀdithiolꢀ2ꢀthioneꢀ4,5ꢀ
dithiolato)nickelate ([Bu4N][Ni(Dmit)2]) was syntheꢀ
sized following the reported method in [24]. The comꢀ
microcrystalline samples from 1.8 to 300 K under a
magnetic field of 1000 Oe, using a Quantum Design
MPMSꢀXL SQUID magnetometer.
Xꢀray crystallography. Single crystals of
I and II
plexes,
bromide ([4
ethylbenzyl)pyrazinium bromide ([4
1ꢀNꢀ(4
ꢀCF3ꢀBzPy]Br) and 1ꢀNꢀ(4
ꢀCF3ꢀBzPy]Br)
'
ꢀtrifluoromethylbenzyl)pyridinium
suitable for Xꢀray diffraction study were, respectively,
selected and mounted on a glass capillary, and the difꢀ
fraction intensity data were collected at 293 K (or 296 K)
by a Bruker AXS SMART diffractometer equipped
'
'
ꢀtrifluoromꢀ
'
were prepared utilizing a routine literature procedure
[22, 23].
with CCD area detector and Mo
K
(
λ
= 0.71073
and II were solved
using direct method and refined with the SHELXꢀ97
[26] by the fullꢀmatrix leastꢀsquares procedure on F2
Å)
α
Synthesis of I and II. The procedures for preparing
radiation [25]. The structures of
I
I
and II are similar to each other, and the general proꢀ
cess of preparation is described below, the equivalents
of (Bu4N)[Ni(Dmit)2] and [4 ꢀCF3ꢀBzPy]Br for
and [4 ꢀCF3ꢀBzPz]Br for II dissolved in acetonitrile
,
'
I,
respectively. All nonꢀhydrogen atoms were refined
anisotropically and the hydrogen atoms were introꢀ
duced at calculated positions. The trifluoromethyl
'
are mixed at room temperature, the immediately
formed precipitate was separated and dried in vacuum.
The yield was ∼60%. The precipitate is then reꢀdisꢀ
solved in acetone. As the acetone solution evaporated
slowly at room temperature, the plateꢀlike darkꢀgreen
crystals, which are suitable for Xꢀray diffraction, were
obtained after 5–7 days.
group exhibits disorder in the crystal structures of both
I
and II, and each fluorine atom has two sites, which ocꢀ
cupation factor was refined. The crystallographic details
about data collection and structure refinements for
II are summarized in Table 1. Supplementary material
for structure and II has been deposited with the Camꢀ
bridge Crystallographic Data Centre (no. 802392 (
I and
I
For C19H11NNiF3S10 (
anal. calcd., %: C, 33.09;
Found, %: C, 32.88;
I)
I)
N, 2.03;
N, 2.18;
H, 1.61.
H, 1.86.
and 802393 (II); deposit@ccdc.cam.ac.uk or http://
www. ccdc.cam.ac.uk).
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013

SYNTHESES, CRYSTAL STRUCTURES, AND MAGNETIC PROPERTIES
149
Table 1. Crystallographic data and refinement parameters for complexes
I
and II
Value
Parameter
I
II
Formula weight
Crystal system
Space group
689.60
690.59
Triclinic
Triclinic
⎯
⎯
P
1
P1
a
,
Å
Å
Å
9.3400(16)
11.847(2)
12.102(2)
97.739(2)
91.227(2)
103.538(2)
1288.2(4); 2
1.778
9.3068(7)
11.8007(9)
11.8419(8)
97.1010(10)
91.4030(10)
102.6990(10)
1257.22(16); 2
1.824
b
,
c
,
α
, deg
β
, deg
γ
, deg
Å3
ρcalcd, g cm–1
V
,
; Z
F(000)
694
694
μ
θ
, mm–1
1.598
1.638
Ranges, deg
1.70–25.50
1.74–25.50
Index ranges
–11
–14
–14
≤
h
k
l
≤
≤
≤
11,
14,
13
–10
–14
≤
h
k
≤
11,
14,
≤
≤
≤
≤
–6
≤
l ≤ 14
Reflections collected
9476
4715
3605
0.0271
336
6883
4643
3708
Independent reflections
Observed data,
Rint
I
> 2σ(I)
0.0364
335
Parameters
Goodness of fit on F 2
Final indices ( > 2
indices (all data)*
Largest diff. peak and hole,
1.060
0.966
R
I
σ(I
))*
R
1 = 0.0352, wR2 = 0.0869
1 = 0.0488, wR2 = 0.0961
0.326/–0.385
R
1 = 0.0312, wR2 = 0.0757
1 = 0.0406, wR2 = 0.0791
0.432/–0.377
R
R
R
e
Å–3
1 2
2
2
⎡
⎤
wR
= ||F | – |F ||/|F |,
o c o
=
F 2 − Fc2
w F 2
.
∑w ∑
(
∑
*
R
Σ
2
o
)
(
o
)
1
⎢
⎣
⎥
⎦
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013

150
ZHANG et al.
(a)
S(8)
S(7)
C(5)
S(6)
C(4)
S(5)
Ni(1)
S(9)
C(10)
C(6)
C(3)
C(9)
C(8)
S(4)
C(11)
S(10)
F(2)
C(1)
S(1)
N(1)
C(19)
C(18)
C(2)
S(2)
C(13)
S(3)
F(5)
C(7)
C(12)
C(16)
F(4)
F(3)
C(17)
F(1)
C(14)
C(15)
F(6)
(b)
x
z
Fig. 1. ORTEP view with nonꢀhydrogen atomic numbering scheme and the thermal ellipsoids at the 30% probability level, all
hydrogen atoms omitted for clarity (a) and packing diagram projected along axis which shows a chairꢀtype cation dimer and an
y
anion ladderꢀtype chain formed via lateralꢀtoꢀlateral S⋅⋅⋅S contacts for I (b).
RESULTS AND DISCUSSION
Two neighboring anions form a faceꢀtoꢀface
dimer with the distance of 3.631 between the mean
molecular planes (which are defined by four coordiꢀ
nated S atoms), and such types of ꢀtype dimers are
arranged into a ladderꢀtype chain via lateralꢀtoꢀlateral
π
ꢀtype
Å
Complex I crystallizes in triclinic space group
P1
with one [Ni(Dmit)2]– anion and one cation in an
asymmetric unit (Fig. 1a). The [Ni(Dmit)2]–
monoanion shows an approximately planar geometry,
in which the Ni–S distances range from 2.1528(9) to
π
S
⋅⋅⋅S contacts with the shorter S⋅⋅⋅S separations of
Å (the symꢀ
S(7)⋅⋅⋅S(2)#1 3.471 and S(7)⋅⋅⋅S(3)#1 3.562
#1
metric code:
x, –1 +
y,
z
) along crystallographic
…
axis direction (Fig. 1b), whilst the shortest S S conꢀ
2.1693(8)
and 93.58(3)
parable to the reported [Ni(Dmit)2]– complexes
[22, 23]. The 4 ꢀshape
ꢀCF3ꢀBzPy+ cation shows a
conformation with a dihedral angle of 68.04 between
the phenyl and pyridyl rings; the phenyl and the pyꢀ
ridyl rings make a dihedral angle of 51.79 and 63.88
Å
and two SNiS bite angles are 92.85(3)
°
°. These geometric parameters are comꢀ
y
tact, S(5)⋅⋅⋅S(5)#2 (symmetric code: #2 1 –
is 3.840 between two nearest neighboring ladderꢀ
x, 1 – y, –z),
'
Λ
Å
type anion chains. Obviously, this distance is larger
than the sum of van der Waals radii of two S atoms
(3.6 Å) [27]. Two adjacent cations are adopted a chairꢀ
°
°
°
type alignment to form a cationic dimer, as demonꢀ
strated in Fig. 1b. Their phenyl rings are parallel to
with the reference plane, N(1)C(12)C(13). It is noted
that the trifluoromethyl group shows structurally disꢀ
order with two sites for each fluorine atom, the site ocꢀ each other with a planeꢀtoꢀplane distance of 4.087
cupancy factor was refined as 0.61 for F(1), F(2), and Such kinds of cation dimers fill in the space between
F(3) atoms and 0.39 for F(4), F(5), and F(6) atoms. the spin ladders, and there only exist weak
Å.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013

SYNTHESES, CRYSTAL STRUCTURES, AND MAGNETIC PROPERTIES
151
(a)
Ni
S
N
C
H
F
z
y
(b)
z
x
Fig. 2. Packing diagrams for II projected along x axis (a) and y axis (b).
van der Waals forces between the adjacent anions and
cations besides electrostatic attraction.
S
⋅⋅⋅S separations of S(7)⋅⋅⋅S(2)#1 3.515
ric code: #1
, –1 +
The plots of χm as a function of temperature are disꢀ
played in Fig. 4 for and II, where χm represents the
Å
(the symmetꢀ
x
y, z), which is shown in Fig. 3b.
Complex II is isostructural with . Two complexes
I
I
exhibit very similar cell parameters (Table 1, Fig. 2)
and packing structures. The molecular structure of II
is displayed in Fig. 3a. The bond lengths and bond anꢀ
gles in the planar [Ni(Dmit)2]– moiety, summarized in
Table 2, are normal. The characteristic dihedral angles
molar magnetic susceptibility of one [Ni(Dmit)2]–
monoanion per formula unit. Two complexes show a
similar magnetic behavior, namely, the χm value of
and II gradually decrease in the temperature range of
75–300 K, indicating the existence of a spin gap, while
increases below
rie paramagnetic behavior of
I
in the
tween the phenyl and pyrizyl rings as well as 81.42
86.76
reference plane, N(1)C(11)C(12), respectively. It is
similar to that the anions form the ladderꢀtype chain
along crystallographic axis via faceꢀtoꢀface stack
(with the distance of 3.576 between the mean moꢀ
Λ
ꢀshape 4
'
ꢀCF3ꢀBzPz+ cation are 70.14
°
beꢀ
∼
60 K upon cooling. The typical Cuꢀ
and II in low temperaꢀ
°
and
I
°
between the phenyl, the pyrizyl rings with the
ture region arises from the magnetic impurity caused
by the lattice defects.
I
From the viewpoint of crystal structure, the magꢀ
netic exchange interaction is stronger in a faceꢀtoꢀface
stacking
y
Å
2–
π
ꢀtype [Ni(Dmit)2]2 dimer than a lateralꢀ
2−
lecular planes defined by four coordinated S atoms)
and lateralꢀtoꢀlateral S⋅⋅⋅S contacts (with the shorter
toꢀlateral aligning
dimer within a ladꢀ
Ni Dmit
(
)
]
[
2
2
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013

152
ZHANG et al.
S(7)
(a)
C(5)
S(6) C(4)
S(8)
S(5)
Ni(1)
C(6)
S(9)
S(4)
C(3)
S(2)
S(10)
C(11)
F(4)
F(2)
F(3)
C(16)
C(1) S(1)
C(17)
C(18)
C(2)
F(5)
C(15)
F(1)
S(3)
F(6)
C(12)
C(14)
C(13)
N(1)
C(7)
C(8)
N(2)
C(10)
C(9)
(b)
y
x
z
(c)
Fig. 3. ORTEP view with nonꢀhydrogen atomic numbering scheme and the thermal ellipsoids at the 30% probability level, all
hydrogen atoms omitted for clarity (a), side (b) and top (c) views of oneꢀdimensional ladderꢀtype arrangement of anions along
axis for II
y
.
derꢀtype chain, since the magnetic orbitals overlap beꢀ
tween two [Ni(Dmit)2]– monomers is larger in the
former case than in the last case; alternatively, the
magnetic exchange interaction between the neighborꢀ
ing ladderꢀtype chains could be ignored owing to the
interatomic separations between the adjacent
[Ni(Dmit)2]– monomers being larger than the sum of
their van der Waals atomic radii. As aboveꢀthought,
two kinds of magnetic exchange models, a simple diꢀ
nuclear (the faceꢀtoꢀface stacking dimer) or a twoꢀ
legged spinꢀladder, are used to analyze the magnetic
In Eq. (1) and Eq. (2), the parameters J and zJ' repꢀ
resent the magnetic exchange constants of intradimer
(faceꢀtoꢀface stacking dimer) and interdimer, respecꢀ
tively; other symbols have their normal meanings. An
then, the variable temperature magnetic susceptibiliꢀ
ties of
dinuclear magnetic exchange formulas Eq. (1
Eq. (2 ) (where χ0 is the sum of the core diamagnetism
from atoms together with the van Vleck paramagnetic
components and the term of represents the Curieꢀ
I
and II were, respectively, fitted to the simple
′) and
′
C/T
type paramagnetic impurity), while the fits are failed
to give the reasonable parameters (Fig. 5), suggesting
the twoꢀlegged spinꢀladder magnetic exchange model
is probably better to understand the magnetic properꢀ
properties of
I and II. For a dinuclear magnetic exꢀ
change model, the molar magnetic susceptibility as a
function of temperature can be expressed as
ties of I and II:
Blaney
⎯
Bowers equation, Eq. (1), which is deduced
ˆ
ꢀ ꢀ
from spin Hamiltonian
or the modified
H = −2JS1S2,
C
T
(1′)
(2′)
χm = χdimer
+
+ χ0,
form, Eq. (2), if the magnetic exchange interactions
between the neighboring dimers are further considꢀ
ered:
χdimer
C
T
χm =
+
+ χ0.
1 − zJ' Ng2β χ
2
−1
(
)
dimer
2
Ng2β
kBT
⎡
⎛
⎞⎤
−2J
k T
B
(1)
(2)
χdimer
=
3 + exp
,
⎜
⎝
⎟
⎥
⎠⎦
⎢
⎣
Since the magnetic susceptibility exhibit an expoꢀ
nential decay upon cooling (in the region of 75–300 K)
χdimer
1 − zJ' Ng2β χ
χm =
.
to indicate the existence of a spin gap for
magnetic behavior in lowꢀtemperature region is exꢀ
I and II, the
2
(
)
dimer
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013

SYNTHESES, CRYSTAL STRUCTURES, AND MAGNETIC PROPERTIES
153
Table 2. Characteristic bond lengths and angles in
pected to be well demonstrated by the Troyer expresꢀ
sion (Eq. (3)) for a twoꢀlegged spinꢀladder system with
[Ni(Dmit)2]– moiety of
I and II
∠
2
S
= 1/2 [28]:
c1 b1
b2 c2
e2
a2 S
d1 S
Sa1
S
S
d2
d3
f2
f1
∠
1
∠
3
⎛
⎞
Ni
S
e1
α
Δ
S
(3)
χm(spin − ladder) =
exp −
,
⎜
⎟
⎠
γ
d4
S a4
a3S
b3 c3
∠
4
k T
B
T
c4 b4
S
⎝
where
of the excitation energy,
and 1 [29]; and is the finite energy gap in the spinꢀ
α
is a constant corresponding to the dispersion
γ
is a constant between 0.5
Value
Δ
Parameter
excitation spectrum. Taking into account the contriꢀ
bution of the core diamagnetism and Curieꢀtype paraꢀ
I
II
magnetism, the magnetic susceptibility data of
in lowꢀtemperature region were fitted to Eq. (3
give the parameters and χ0 of 0.34, 657 K, 0.57,
2.55
10–3 emu K mol–1 and –3.5 10–4 emu mol–1 for
(corresponding to temperature region of 1.8–143 K)
as well as 0.59, 537 K, 0.63, 2.29
10–3 emu K mol–1
and –5.3
10–4 emu mol–1 for II (corresponding to
temperature region of 1.8–138 K):
I
and II
2.1528(9)
2.1691(6)
a1,
a2,
a3,
a4,
b1,
b2,
b3,
b4,
c1,
c2,
c3,
c4,
d1,
d2,
d3,
d4,
e1,
e2,
f1,
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
′), to
α,
γ, Δ, C
2.1625(9)
2.1693(8)
2.1670(9)
1.703(3)
1.720(3)
1.723(3)
1.716(3)
1.738(3)
1.744(3)
1.723(3)
1.716(3)
1.721(3)
1.720(3)
1.726(3)
1.740(3)
1.362(4)
1.350(4)
1.643(3)
1.658(3)
92.85(3)
86.02(3)
93.58(3)
87.59(3)
2.1657(6)
2.1552(6)
2.1623(6)
1.723(2)
1.717(2)
1.707(2)
1.721(2)
1.740(2)
1.747(2)
1.740(2)
1.745(2)
1.721(2)
1.728(3)
1.727(3)
1.721(2)
1.348(3)
1.359(3)
1.660(2)
1.644(2)
93.51(2)
87.41(2)
92.93(2)
86.15(2)
×
×
I
×
×
C
T
(3′)
χm = χm(spin − ladder) + + χ0.
Alternatively, in the highꢀtemperature region, χm of
a twoꢀlegged spin ladder with antiferromagnetic exꢀ
change interaction is the function of the exchange inꢀ
teractions along the legs (J) and the rung (J') of the
ladder, that can be approximated by Eq. (4), given by
Barnes and Riera [18, 30]:
χm(spin − ladder) =
(4)
−1
−2
−3
⎤
,
⎥
⎦
1
2
1
2
3
16
⎡
= 0.375 T
−
J + J' T
+
JJ'T
)
(
⎢
⎣
C
T
(4′)
χm = χm(spin − ladder) + + χ0.
The experimental magnetic susceptibility data in
highꢀtemperature region were fitted to Eq. (4 ) to
= 782 K and
was fixed as 2.55
′
produce the parameters of
–1.8
10–4 emu mol–1
10⎯ 3 emu K mol–1) for
J
(
= 86 K, J'
C
×
×
I
(corresponding to temperaꢀ
ture range of 143–300 K) versus = 19 K, = 543 K,
= 2.4
10–3 emu K mol–1 and –2.5 10–4 emu mol–1
J
J'
C
×
×
for II (corresponding to temperature range of 138–
300 K). Since the spin gap in a Heisenberg antiferroꢀ
magnetic spinꢀladder is related to J and J' as
J 2
(5)
Δ ≈ J' − J +
,
2J'
values were further evaluated as 701 K for
524 K for II from their and J' parameters fitted by the
f2,
the
Δ
I
and
J
∠1, deg
∠2, deg
∠3, deg
∠
4, deg
magnetic susceptibility data in highꢀtemperature reꢀ
gion, these estimated spin gap values are closed to
those calculated from Eq. (3), respectively.
In summary, two isostructural spinꢀladder comꢀ
plexes based on bis(2ꢀthioxoꢀ1,3ꢀdithioleꢀ4,5ꢀdithiꢀ
olato)nickelate monoanion building block have been
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013

154
ZHANG et al.
(a)
(a)
Data: Data2_Xm
Model: dimer1
1.0
0.8
0.6
0.4
0.2
0
1.0
0.8
Chiˆ2 = 4.2402E–10
Rˆ2 = 0.99455
c
q
Jex
zJ
0.00259
2
0.00003
0.6
0
–275.4144
872.57573
2.18075
40.30644
3.9814E–6
0.4
chi0 –0.00036
0.2
Data: Data2_Xm
Model: dimer
0
Chiˆ2 = 3.9802E–10
2 = 0.99488
–0.2
–0.4
R
ˆ
c
0.00258
chi0 –0.00036
0.00003
–0.2
3.8689E–6
0.03259
3.64763
q
Jex
2.59828
–305.73607
0
50 100 150 200 250 300
, K
(b)
–0.4
T
Experemental
Spinꢀgap
Spinꢀladder
0.6
0.4
0
50
100
150
200
250
300
T, K
0.8
0.6
Data: Data1_Xm
Model: dimer1
(b)
0.2
Chiˆ2 = 1.3815E–9
R
ˆ
2 = 0.98937
0
c
q
0.00234
1.29386
0.00006
0.07801
3.32256
50.00195
7.5362E–6
0.4
–0.2
–0.4
–0.6
Jex
zJ
–195.7349
1319.48411
chi0 –0.00054
0.2
0
Data: Data1_Xm
Model: dimer
0
50 100 150 200 250 300
, K
T
Chiˆ2 = 1.975E–9
–0.2
–0.4
–0.6
Rˆ2 = 0.98457
c
0.00235
0.00007
9.0398E–6
0.0391
Fig. 4. Plots of
experimental data; lines: fits.
χ
versus T for I (a) and II (b); open circles:
M
chi0 –0.00054
q
Jex
2.61174
–250.23859
4.14809
synthesized and characterized structurally and magꢀ
netically. Two complexes show a similar magnetic beꢀ
havior, the magnetic exchange natures along the legs
0
50
100
150
200
250
300
T, K
Fig. 5. Magnetic susceptibility,
χ
, as a function of temꢀ
(J) and the rung (J') of the spin ladder are antiferroꢀ
m
perature of I (a) and II (b) (open circles: experimental daꢀ
magnetic, and the magnetic susceptibility data can be
fitted to a Heisenberg antiferromagnetic twoꢀlegged
spin ladder formula in highꢀtemperature region and
reproduced well by the Troyer expression in lowꢀtemꢀ
perature region; the spinꢀgap values, obtained, respecꢀ
tively, from the fits of magnetic susceptibility data in
highꢀ and lowꢀtemperature regions, are closed to each
other, indicating the chose magnetic exchange model
and the results of fits are reasonable.
ta; dot lines: fits using a model of isolated spinꢀdimer and
the dimer with magnetic exchange interactions between
dimers, respectively).
nos. KJ2012ZD11, 11KJD150004, 1002020B, and
21171097).
REFERENCE
1. Robertson, N. and Cronin, L. , Coord. Chem. Rev.,
2002, vol. 227, p. 93.
2. Cassoux, P., Coord. Chem. Rev., 1999, vol. 185, p. 213.
3. Akutagawa, T. and Nakamura, T., Coord. Chem. Rev.,
ACKNOWLEDGMENTS
2000, vol. 198, p. 297.
4. Canadell, E., Coord. Chem. Rev., 1999, vol. 186, p. 629.
5. Kato, R., Chem. Rev., 2004, vol. 104, p. 5319.
The authors thank the Natural Science Foundation
of High Learning Institutions of Anhui Province, Natꢀ
ural Science Foundation of High Learning Instituꢀ
tions of Jiangsu Province, Postdoctoral Science Founꢀ
dation of Jiangsu Province and National Nature Sciꢀ
ence Foundation of China for financial support (grant
6. Fourmigu
7. Kobayashi, A., Fujiwara, E., and Kobayashi, H., Chem.
Rev., 2004, vol. 104, p. 5243.
é, M., Acc. Chem. Res., 2004, vol. 37, p. 179.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013

SYNTHESES, CRYSTAL STRUCTURES, AND MAGNETIC PROPERTIES
155
8. Ouahab, L., Coord. Chem. Rev., 1998, vol. 178, p. 1501.
9. Olk, R.M., Olk, B., Dietzsch, W., et al., Coord. Chem
Rev., 1992, vol. 117, p. 99.
10. Duan, H.B., Ren, X.M., and Meng, Q.J., Coord. Chem
Rev., 2010, vol. 254, p. 1509.
20. Kosaka, Y., Yamamoto, H.M., Nakao, A., et al., J. Am.
Chem. Soc., 2007, vol. 129, p. 3054.
.
.
21. Akutagawa, T., Shitagami, K., Aonuma, M., et al.,
Inorg. Chem., 2009, vol. 48, p. 4454.
22. Chen, Y.C., Liu, G.X., Song, Y., et al., Polyhedron
2005, vol. 24, p. 2269.
,
11. Tian, Z.F., Duan, H.B., Ren, X.M., et al.,
Chem , 2009, vol. 113, p. 8278.
12. Tian, Z.F., Ren, X.M., Li, Y.Z., et al., Inorg. Chem.,
J. Phys.
.
B
23. Zang, S.Q., Ren, X.M., Song, Y., et al., Inorg. Chem.,
2009, vol. 48, p. 9623.
2007, vol. 46, p. 8102.
13. Ren, X.M., Akutagawa, T., Noro, S., et al., J. Phys.
Chem. B, 2006, vol. 110, p. 7671.
14. Ren, X.M., Akutagawa, T., Nishihara, S., et al., J. Phys.
Chem. B, 2005, vol. 109, p. 16610.
15. Dang, D.B., Ni, C.L., Bai, Y., et al., Chem. Lett., 2005,
24. Steimecke, G., Sieler, H., and Kirmse, J.R., Phos. Sulꢀ
fur
25. Bruker, SAINT (version 6.22) and SMART (version
5.625), Madison (WI, USA): BrukerꢀAXS Inc., 2001.
26. Sheldrick, G.M., SHELXSꢀ97 and SHELXLꢀ97, G tꢀ
tingen (Germany): Univ. of G ttingen, 1997.
27. Bondi, A., J. Phys. Chem., 1964, vol. 68, p. 441.
28. Troyer, M., Tsunetsugu, H., and W rtz, D., Phys. Rev.
, 1994, vol. 50, p.13515.
29. Johnston, D.C., Kremer, R.K., Troyer, M., et al., Phys.
Rev. B, 2000, vol. 61, p. 9558.
. Relat. Elem., 1979, vol. 7, p. 49.
ö
vol. 5, p. 680.
ö
16. Ren, X.M., Meng, Q.J., Song, Y., et al., Inorg. Chem.,
2002, vol. 41, p. 5686.
17. Takamatsu, N., Akutagawa, T., Hasegawa, T., et al.,
Inorg. Chem., 2000, vol. 39, p. 870.
18. Nishihara, S., Akutagawa, T., Hasegawa, T., et al.,
Chem. Commun., 2002, p. 408.
ü
B
19. Nishihara, S., Akutagawa, T., Hasegawa, T., et al., 30. Barnes, T. and Riera, J., Phys. Rev
J. Solid. State Chem., 2002, vol. 168, p. 661. p. 6817.
. B, 1994, vol. 50,
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 1
2013