Syntheses, crystal structures, and magnetic properties of two novel Ni(mnt)2-based molecular magnetic materials containing substituted triphenylphosphinium

Article abstract of DOI:10.1016/j.ica.2007.07.004

Two novel molecular magnetic materials, [RBzTPP][Ni(mnt)₂] (mnt^2- = maleonitriledithiolate, [RBzTPP]⁺ = 4-R-benzyltriphenylphosphinium; R = CN (1), Cl (2)) were synthesized and characterized by X-ray diffraction, IR spectroscopy, and magnetic susceptibility measurements. In crystal of 1, the [Ni(mnt)₂]^- anions form a dimer via Ni?S and π?π stacking interactions between Ni(mnt)₂ planes, and the C-H?Ni and C-H?N H-bonding interactions are found between the [Ni(mnt)₂]^- anions and the neighboring [CNBzTPP]⁺ cations. The anions and cations of 2 stack into well-segregated columns in the solid state; and the Ni(III) ions form a 1D alternating chain in a Ni(mnt)₂ column through intermolecular Ni?S, or π?π interactions with the Ni?Ni distances of 3.900, 4.198, and 4.165 A?. Magnetic susceptibility measurements for these complexes in the temperature range 1.8-300 K show that the overall magnetic behavior for 1 and 2 indicates the presence of antiferromagnetic interaction, but 1 exhibits an activated magnetic behavior in the high-temperature (HT) region together with a Curie tail in the low-temperature (LT) region.

Full text of DOI:10.1016/j.ica.2007.07.004

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Inorganica Chimica Acta 361 (2008) 400–406
www.elsevier.com/locate/ica
Note
Syntheses, crystal structures, and magnetic properties of two novel
Ni(mnt)2-based molecular magnetic materials containing substituted
triphenylphosphinium
a
a,b,
a,b
Jiarong Zhou , Chunlin Ni
*, Linliang Yu a,b, Lemin Yang
a
Department of Applied Chemistry, College of Science, South China Agricultural University, 510642 Guangzhou, PR China
b
Centre of Inorganic Functional Materials, South China Agricultural University, 510642 Guangzhou, PR China
Received 20 February 2007; received in revised form 19 May 2007; accepted 8 July 2007
Available online 13 July 2007
Abstract
Two novel molecular magnetic materials, [RBzTPP][Ni(mnt)2] (mnt2ꢀ = maleonitriledithiolate, [RBzTPP]+ = 4-R-benzyltriphenyl-
phosphinium; R = CN (1), Cl (2)) were synthesized and characterized by X-ray diffraction, IR spectroscopy, and magnetic susceptibility
measurements. In crystal of 1, the [Ni(mnt)2]ꢀ anions form a dimer via Niꢁ ꢁ ꢁS and pꢁ ꢁ ꢁp stacking interactions between Ni(mnt)2 planes,
and the C–Hꢁ ꢁ ꢁNi and C–Hꢁ ꢁ ꢁN H-bonding interactions are found between the [Ni(mnt)2]ꢀ anions and the neighboring [CNBzTPP]+
cations. The anions and cations of 2 stack into well-segregated columns in the solid state; and the Ni(III) ions form a 1D alternating
chain in a Ni(mnt)2 column through intermolecular Niꢁ ꢁ ꢁS, or pꢁ ꢁ ꢁp interactions with the Niꢁ ꢁ ꢁNi distances of 3.900, 4.198, and
˚
4.165 A. Magnetic susceptibility measurements for these complexes in the temperature range 1.8–300 K show that the overall magnetic
behavior for 1 and 2 indicates the presence of antiferromagnetic interaction, but 1 exhibits an activated magnetic behavior in the high-
temperature (HT) region together with a Curie tail in the low-temperature (LT) region.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Bis(maleonitriledithiolato)nickelate complex; Substituted triphenylphosphinium; Crystal structure; H-Bonding interaction; Magnetic prop-
erties
1. Introduction
from ferromagnetic to diamagnetic coupling, meta-magne-
tism, and spin-Peierls-like transitions [6–11]. Of key impor-
tance in design of such materials is to find more suitable
multifunctional organic cations to tune the crystal stacking
structure of the [Ni(mnt)2]ꢀ anion. One of the advantages
of using organic cation as countercation for [M(mnt)2]ꢀ
monoanion is that the topology and size of the counterca-
tion in Ni(mnt)2 complex may play an important role in
controlling the stacking pattern of anions and cations,
which further influence the magnetic properties. Some sur-
prising results in our previous systematic studies on a series
of ionic complexes composed of [Ni(mnt)2]ꢀ anion and
substituted benzylpyridinium cation prompted us to inves-
tigate the effects of some larger organic cations on the
stacking pattern of Ni(mnt)2 complexes [12–20]. We herein
introduced two substituted benzyltripenylphosphiniums
Great interest in recent years has been directed toward
the development of structural and functional analogues
of molecular solids based on metal dithiolene complexes
by virtue of their ability to assemble in the solid state with
short sulfur–sulfur, metal–sulfur or pꢁ ꢁ ꢁp stacking interac-
tions [1–5]. The planar anion [M(mnt)2]ꢀ (M = Ni, Pd or
Pt) had been proved to be good building block to construct
molecular materials, which exhibit versatile magnetic prop-
erties such as ferromagnetic ordering, magnetic transition
*
Corresponding author. Address: Department of Applied Chemistry,
College of Science, South China Agricultural University, 510642 Guangz-
hou, PR China. Tel.: +86 20 85282568; fax: +86 20 85282366.
E-mail address: niclchem@scau.edu.cn (C. Ni).
0020-1693/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.07.004

J. Zhou et al. / Inorganica Chimica Acta 361 (2008) 400–406
401
Table 1
netic behavior in the high-temperature (HT) region
together with a Curie tail in the low-temperature (LT)
region.
Crystal data and structure refinement for 1 and 2
Compound
1
2
Empirical formula
Formula weight
T (K)
C34H21N5NiPS4
717.48
293(2)
0.71073
triclinic
C33H21N4NiClPS4
726.91
293(2)
0.71073
monoclinic
P21/c
15.767(3)
23.393(4)
21.682(3)
90
2. Experimental
˚
Wavelength (A)
All reagents and chemicals were purchased from com-
mercial sources and were used without further purification.
Disodium maleonitriledithiolate (Na2mnt) was synthesized
by a published procedure [21]. 4-Cyanobenzyltriphenyl-
phosphinium bromide ([CNBzTPP]Br) and 1-(40-chlorob-
enzyl) triphenylphosphinium bromide ([ClBzTPP]Br) were
prepared by the literature methods [22]. A similar method
for preparing [BzTPP]2[Ni(mnt)2] was used to prepare
[CNBzTPP]2[Ni(mnt)2] and [ClBzTPP]2[Ni(mnt)2] [23].
Crystal system
Space group
ꢀ
P1
˚
a (A)
11.815(2)
12.613(2)
12.120(2)
114.68(1)
101.49(1)
90.77(1)
1677.9(4)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
123.91(1)
90
6637.2(19)
8
3
˚
Volume (A )
Z
Dcalc (mg/m3)
1.420
1.455
Absorption coefficient 0.907
(mmꢀ1
F(000)
0.995
2.1. Synthesis of [CNBzTPP][Ni(mnt)2] (1)
)
734
2968
0.48 · 0.34 · 0.17
39411
An acetone solution (10 cm3) of I2 (240 mg, 0.93 mmol)
was slowly added to an acetone solution (20 cm3) of
[CNBzTPP]2[Ni(mnt)2] (1645 mg, 1.50 mmol) and the mix-
ture was stirred for 12 h. MeOH (120 cm3) was then added,
and the mixture allowed to stand overnight, 915 mg of
black micro-crystals formed were filtered off, washed with
MeOH and dried in vacuum. Yield: 85%. Anal. Calc. for
C34H21N5NiPS4: C, 56.92; H, 2.95; N, 9.76. Found: C,
56.87; H, 3.06; N, 9.59%. IR spectrum (cmꢀ1): m(CN),
2226, 2208 s; m(C@C) of mnt2ꢀ, 1437 s.
Crystal size (mm)
Reflections collected
Independent
0.40 · 0.30 · 0.30
8354
5787 (0.029)
13485 (0.032)
reflections (Rint
)
Refinement method
full-matrix least-
squares on F2
5787/0/307
full-matrix least-
squares on F2
13485/0/793
Data/restraints/
parameters
Goodness of fit on F2 1.040
1.001
Final R indices
[I > 2r(I)]
Final R indices (all
data)
R1 = 0.0547,
R1 = 0.0375,
wR2 = 0.0789
R1 = 0.0675,
wR2 = 0.0914
wR2 = 0.1179
R1 = 0.0826,
wR2 = 0.1289
2.2. Synthesis of [ClBzTPP][Ni(mnt)2] (2)
The procedure for preparing 2 is similar to that for 1.
Yield: 87%. Anal. Calc. for C33H21N4NiClPS4 (2): C,
54.53; H, 2.91; N, 7.71. Found: C, 54.47; H, 2.98; N,
7.54%. IR (KBr, cmꢀ1): IR spectrum (cmꢀ1): m(CN), 2206
s; m(C@C) of mnt2ꢀ, 1436 s.
into the Ni(mnt)2 system and obtained two newly prepared
Ni(mnt)2-based molecular magnetic materials: [CNBzTPP]
[Ni(mnt)2] (1) and [ClBzTPP][Ni(mnt)2] (2), whose synthe-
ses, crystal structures and magnetic properties are
described. Although these molecular solids show antiferro-
magnetic coupling behavior, 1 exhibits an activated mag-
Table 2
˚
Selected bond lengths (A) and bond angles (ꢁ) for 1
˚
Bond length (A)
Ni(1)–S(1)
Ni(1)–S(2)
Ni(1)–S(3)
Ni(1)–S(4)
N(1)–C(1)
N(2)–C(4)
N(3)–C(5)
N(4)–C(8)
2.142(1)
2.140(1)
2.143(1)
2.133(1)
1.130(8)
1.134(7)
1.135(7)
1.138(7)
S(1)–C(2)
S(2)–C(3)
S(3)–C(6)
S(4)–C(7)
P(1)–C(15)
P(1)–C(21)
P(1)–C(27)
P(1)–C(33)
1.712(4)
1.711(5)
1.714(4)
1.728(5)
1.813(4)
1.784(4)
1.790(4)
1.795(4)
Bond angles (ꢁ)
S(1)–Ni(1)–S(2)
S(1)–Ni(1)–S(4)
S(2)–Ni(1)–S(3)
S(3)–Ni(1)–S(4)
Ni(1)–S(1)–C(2)
Ni(1)–S(2)–C(3)
Ni(1)–S(3)–C(6)
Ni(1)–S(4)–C(7)
92.48(5)
87.11(4)
88.28(4)
P(1)–C(15)–C(14)
P(1)–C(21)–C(16)
P(1)–C(21)–C(20)
P(1)–C(27)–C(26)
P(1)–C(27)–C(22)
P(1)–C(33)–C(28)
P(1)–C(33)–C(32)
C(15)–P(1)–C(21)
117.9(3)
121.4(3)
119.1(3)
118.8(3)
121.6(3)
119.7(3)
120.6(3)
110.76(17)
92.23(5)
103.28(18)
103.07(16)
103.49(18)
103.30(16)
Fig. 1. ORTEP plot (30% probability ellipsoids) showing the molecular
structure of 1.

402
J. Zhou et al. / Inorganica Chimica Acta 361 (2008) 400–406
a
b
c
Fig. 2. (a) The packing diagram of the anions for 1. (b) Mode of overlapping of [Ni(mnt)2]ꢀ anions for 1. (c) The weak C–Hꢁ ꢁ ꢁNi and C–Hꢁ ꢁ ꢁN
H-bonding interactions (dashed lines) between the anions and cations for 1.
The black single crystals suitable for the X-ray structure
analysis were obtained by slowly evaporating the MeCN
and i-PrOH (v/v = 2:1) mixed solution of 1 and 2 about
15 days at room temperature.
2.3. Instrumental procedures
IR spectra were recorded on a Nicolet FT-IR spectro-
photometer in 4000–400 cmꢀ1 regions as KBr pellets.

J. Zhou et al. / Inorganica Chimica Acta 361 (2008) 400–406
403
Table 3
Selected bond lengths (A) and bond angles (ꢁ) for 2
˚
˚
Bond length (A)
Ni(1)–S(1)
Ni(1)–S(2)
Ni(1)–S(3)
Ni(1)–S(4)
Ni(2)–S(5)
Ni(2)–S(6)
Ni(2)–S(7)
Ni(2)–S(8)
N(1)–C(1)
N(2)–C(4)
N(3)–C(5)
N(4)–C(8)
N(5)–C(9)
N(6)–C(12)
N(7)–C(13)
N(8)–C(16)
2.143(1)
2.140(1)
2.147(1)
2.144(1)
2.144(1)
2.145(1)
2.139(1)
2.138(1)
1.138(4)
1.139(5)
1.138(4)
1.139(4)
1.142(4)
1.131(4)
1.143(5)
1.136(5)
S(1)–C(2)
S(2)–C(3)
S(3)–C(6)
S(4)–C(7)
S(5)–C(10)
S(6)–C(11)
S(7)–C(14)
S(8)–C(15)
P(1)–C(23)
P(1)–C(29)
P(1)–C(35)
P(1)–C(41)
P(2)–C(48)
P(2)–C(54)
P(2)–C(60)
P(2)–C(66)
1.714(3)
1.721(3)
1.712(3)
1.715(3)
1.713(3)
1.711(3)
1.721(3)
1.719(3)
1.806(2)
1.785(3)
1.785(3)
1.787(2)
1.808(3)
1.782(3)
1.786(3)
1.795(3)
Bond angles (ꢁ)
S(1)–Ni(1)–S(2)
S(1)–Ni(1)–S(4)
S(2)–Ni(1)–S(3)
S(3)–Ni(1)–S(4)
S(5)–Ni(2)–S(6)
S(5)–Ni(2)–S(8)
S(6)–Ni(2)–S(7)
S(7)–Ni(2)–S(8)
Ni(1)–S(1)–C(2)
Ni(1)–S(2)–C(3)
Ni(1)–S(3)–C(6)
Ni(1)–S(4)–C(7)
Ni(2)–S(5)–C(10)
Ni(2)–S(6)–C(11)
Ni(2)–S(7)–C(14)
Ni(2)–S(8)–C(15)
92.14(3)
87.39(3)
88.23(4)
92.27(5)
92.56(3)
87.59(3)
87.69(3)
92.17(3)
103.75(9)
103.43(9)
103.46(9)
103.59(9)
103.35(9)
103.24(9)
103.55(11)
103.55(11)
P(1)–C(23)–C(22)
P(1)–C(29)–C(24)
P(1)–C(29)–C(28)
P(1)–C(35)–C(30)
P(1)–C(35)–C(34)
P(1)–C(41)–C(36)
P(1)–C(41)–C(40)
P(2)–C(48)–C(47)
P(2)–C(54)–C(49)
P(2)–C(54)–C(53)
P(2)–C(60)–C(55)
P(2)–C(60)–C(59)
P(2)–C(66)–C(61)
P(2)–C(66)–C(65)
C(23)–P(1)–C(29)
C(48)–P(2)–C(54)
114.7(2)
120.0(3)
120.3(3)
122.3(2)
118.6(2)
121.4(2)
119.8(2)
115.50(18)
120.11(19)
120.3(2)
120.85(18)
119.16(18)
122.4(2)
118.1(2)
109.99(14)
110.07(14)
Fig. 3. ORTEP plot (30% probability ellipsoids) showing the molecular
structure for 2.
Elemental analyses of C, H, and N were run on a Model
240 Perkin–Elmer C H N instrument. Magnetic susceptibil-
ity data on polycrystals sample were collected over the tem-
perature range of 1.8–300 K using a Quantum Design
MPMS-7S super-conducting quantum interference device
(SQUID) magnetometer, and diamagnetic corrections were
made using Pascal’s constants.
[CNBzTPP]+ cation. Fig. 1 shows the molecular structure
of 1. The most relevant bond lengths and bond angles
are given in Table 2. The Ni(1) of the [Ni(mnt)2]ꢀ anion
exhibits the square-planar coordination geometry. The
Ni–S bond distances and the S–Ni–S bond angles (Table
2) within the five-membered rings agree well with those
found in [Ni(mnt)2]ꢀ complexes comprised of [BzTPP]
[Ni(mnt)2] [23]. The [CNBzTPP]+ cation adopts a confor-
mation in which four phenyl rings are twisted relative to
the C(14)–C(15)–P(1) reference plane, with dihedral angles
of 86.3ꢁ, 89.8ꢁ, 43.9ꢁ and 124.8ꢁ for the C(9)–C(14), C(16)–
C(21), C(22)–C(27) and C(28)–C(33) rings, respectively.
The [Ni(mnt)2]ꢀ anions in crystal form dimers via Niꢁ ꢁ ꢁS
and pꢁ ꢁ ꢁp stacking interactions between the Ni(mnt)2
planes (Fig. 2a), and the nearest distance between S of a
Ni(mnt)2 plane and the Ni of the neighboring one is
2.4. Crystal structure determination
Single crystals of [CNBzTPP][Ni(mnt)2] (1) and
[ClBzTPP][Ni(mnt)2] (2) were mounted on a Bruker Smart
APEX CCD area detector using graphite-monochromated
˚
Mo Ka radiation (k = 0.71073 A) by x scan mode. Crystal
data, data collection and refinement details for 1 and 2 are
given in Table 1. The structures were solved by direct meth-
ods and refined on F2 by full-matrix least-squares, employ-
ing Bruker’s SHELXTL [24]. All non-hydrogen atoms were
refined with anisotropic thermal parameters. All H atoms
were placed in calculated positions, assigned fixed isotropic
displacement parameters 1.2 times the equivalent isotropic
U value of the attached atom, and allowed to ride on their
respective parent atoms.
ꢀ
˚
3.731 A. The mode of overlapping of [Ni(mnt)2] anions
˚
with a Niꢁ ꢁ ꢁNi distance of 4.725 A is shown in Fig. 2b.
3. Results and discussion
As shown in Fig. 2c, there are two weak H-bonding inter-
actions between [Ni(mnt)2]ꢀ anion and adjacent
[CNBzTPP]+ cation. One is a weak intramolecular C(23)–
3.1. Description of crystal structures
H(23)ꢁ ꢁ ꢁNi(1)
H-bonding
interaction,
with
a
˚
The X-ray study of [CNBzTPP][Ni(mnt)2] (1) reveals
that the molecule contains one NiðmntÞ2 anion and one
C(23)ꢁ ꢁ ꢁNi(1) distance of 3.754 A. Although regular weak
ꢀ
hydrogen bonding is very common, weak hydrogen bond-

404
J. Zhou et al. / Inorganica Chimica Acta 361 (2008) 400–406
a
b
3.900
3.900
3.900
4.165
4.198
c
Fig. 4. (a) Packing diagram of a unit cell for 2 as viewed along a-axis. (b) Side view of the anions stack of 2 showing the alternating space linear-chain of
[Ni(mnt)2]ꢀ anions. (c) The C–Hꢁ ꢁ ꢁp interactions between the cations for 2.
ing with Ni is rare [25], which is similar to the C–Hꢁ ꢁ ꢁCu
interactions found in the literature [26,27]. Another is an
intermolecular C(10)–H(10)ꢁ ꢁ ꢁN(4) interaction with a
Compound 2 crystallizes in monoclinic lattice and an
asymmetric unit in a cell comprises an ion pair of
[Ni(mnt)2]ꢀ anion and [ClBzTPPl]+ cation as shown in
Fig. 3. The coordination geometry of anion and the confor-
˚
C(10)ꢁ ꢁ ꢁN(4) distance of 3.255 A.

J. Zhou et al. / Inorganica Chimica Acta 361 (2008) 400–406
405
vmT values of 1 and 2 are 0.270, 0.201 emu K molꢀ1, the
values are lower than the expected for magnetically isolated
Ni(III) ions. As the temperature is lowered, compound 1
exhibits an activated magnetic behavior in the high-temper-
ature range together with a Curie tail at lower temperature
range due to magnetic impurities, and 2 shows a magnetic
behavior corresponding to a paramagnetic system with an
antiferromagnetic coupling interaction.
Table 4
Hydrogen bonds for 1 and 2
D–Hꢁ ꢁ ꢁA
d(Dꢁ ꢁ ꢁH)
d(Hꢁ ꢁ ꢁA)
d(Dꢁ ꢁ ꢁA)
\(DHA)
(ꢁ)
˚
˚
˚
(A)
(A)
(A)
Compound 1
C(10)–
H(10)ꢁ ꢁ ꢁN(4)#1
Compound 2
C(18)–
0.93
2.58
3.255(6)
130.0
The dinuclear model formula (1) (the Hamiltonian being
H = ꢀ2JSASB) [28] can be used to fit the magnetic suscep-
tibilities of 1:
H(18)ꢁ ꢁ ꢁN(3)#2
0.93
2.58
2.60
2.59
3.366(4)
3.424(7)
3.447(5)
142.0
143.0
152.0
C(48)–
H(48A)ꢁ ꢁ ꢁN(6)#3 0.97
C(48)–
H(48B)ꢁ ꢁ ꢁCl(1)#4 0.93
Symmetry transformations used to generate equivalent atoms: #1: ꢀx,
ꢀy + 1, ꢀz. + 1. #2: x ꢀ 1, ꢀy + 3/2, z ꢀ 1/2. #3: x + 1, ꢀy + 3/2, z + 1/
2. #4: ꢀx + 1, y ꢀ 1/2, ꢀz + 3/2.
vm ¼ ð2Nb2g2=kTÞð1 ꢀ qÞ=ð3 þ expðꢀ2J=kTÞÞ
þ ðNb2g2=2kTÞq þ v0
ð1Þ
where N, g, k, b and q have their usual meanings [28], and J
is the exchange coupling parameter describing the magnetic
interaction between any two neighboring S = 1/2 spins.
The best-fit parameters obtained by least-squares fit are:
g = 1.96, J = ꢀ441.5 cmꢀ1, q = 8.3 · 10ꢀ3, v0 = 4.0 · 10ꢀ5
mation of cation in 2 are essentially identical to those
described above for 1 (the most relevant bond lengths
and bond angles are listed in Table 3), while the stacking
pattern of anions and cations for 2 (Fig. 4a) is significantly
different from those of 1. The Ni(III) ions form a 1D chain
within a [Ni(mnt)2]ꢀ column through intermolecular
Niꢁ ꢁ ꢁS, Sꢁ ꢁ ꢁS, Niꢁ ꢁ ꢁNi or pꢁ ꢁ ꢁp interactions (Fig. 4b).
Within a [Ni(mnt)2]ꢀ anions stacking column, the nearest
emu molꢀ1 and R = 1.8 · 10ꢀ5 (R is defined as
P
2
2
ðvmcalcd ꢀ vombsdÞ =ðvombsdÞ ). Since the Niꢁ ꢁ ꢁNi distances
˚
˚
(4.198 A and 4.165 A) of anions in 2 are larger than that
(3.900 A) of other anions in nickel(III) ion chains, therefore
˚
the nickel(III) ions magnetic interactions can be neglected,
˚
˚
Niꢁ ꢁ ꢁS and Sꢁ ꢁ ꢁS distances are 3.615 A and 3.807 A, respec-
˚
tively, and the Niꢁ ꢁ ꢁNi distance alternates from 3.900 A,
˚
˚
˚
a
4.198 A, 3.900 A to 4.165 A with the repeating periodicity
of four. Because the cationic stacks mediate the anionic
stacks, the closest Niꢁ ꢁ ꢁNi separation between anion col-
3.2
˚
2.4
1.6
0.8
0.0
umns is 14.374 A, which is much longer than that of intra-
stack. As a result, 2 should possess the ideal 1D alternating
magnetic chain characteristic from the viewpoint of the
crystal structure. As shown in Fig. 4c and Table 4, four
weak
H-bonding
interactions
such
as
C(18)–
H(18)ꢁ ꢁ ꢁN(3), C(48)–H(48A)ꢁ ꢁ ꢁN(6), C(48)–H(48b)ꢁ ꢁ ꢁCl(1)
and C(50)–H(50)ꢁ ꢁ ꢁp are found in the solid of 2.
By comparing the structures of 1 and 2, we conclude
that the stacking and overlapping modes are different when
we have changed the p-substituted group in the benzene of
benzyl group, and the Cl group favors separated columnar
molecular stacks of anions and cations, and the CN group
favors a pair of anions into dimer. In addition, some inter-
molecular contacts of hydrogen bonds such as C–Hꢁ ꢁ ꢁN,
C–Hꢁ ꢁ ꢁCl, C–Hꢁ ꢁ ꢁNi and C–Hꢁ ꢁ ꢁp found between the
adjacent cations and anions may play important roles in
the molecular stabilizing and stacking of 1 and 2.
0
50
100
150
200
250
300
T (K)
1.5
1.2
0.9
0.6
0.3
0.0
b
3.2. Magnetic properties of 1 and 2
The temperature dependence of the magnetic suscepti-
bilities for 1 and 2 was measured under an applied field
of 2000 Oe in the temperature range of 1.8–300 K. The
plots of vm versus T for 1 and 2 are shown in Fig. 5 with
vm being the magnetic susceptibility per nickel atom cor-
rected by the diamagnetic contribution. At 300 K, the
0
50
100
150
200
250
300
T (K)
Fig. 5. Plots of vm vs. T for 1 (a) and 2 (b). The red solid line is reproduced
from the theoretical calculations, and detailed fitting procedure is
described in the text. (For interpretation of the references to color in
this figure legend, the reader is referred to the web version of this article.)

406
J. Zhou et al. / Inorganica Chimica Acta 361 (2008) 400–406
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and the magnetic susceptibility data of 2 can also be analyzed
using simple dinuclear model (Eq. (1)). The best-fit parame-
ters are: g = 1.98, J = ꢀ830.0 cmꢀ1
,
q = 3.1 · 10ꢀ2
,
v0 = 5.1 · 10ꢀ4 emu molꢀ1 and R = 6.1 · 10ꢀ6. The model
provides an excellent fit for 1 and 2 (the solid lines in
Fig. 5a and b), as indicated by the low value of R.
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In conclusion, the crystal structures and magnetic prop-
erties were presented for two noꢀvel molecular magnetiꢀc
materials containing the NiðmntÞ2 anion. The NiðmntÞ2
anions of 1 form dimer via Niꢁ ꢁ ꢁS and pꢁ ꢁ ꢁp stacking inter-
actions between Ni(mnt)2 planes, but the anions and cat-
ions of 2 stack into well-segregated columns in the solid
state; and the Ni(III) ions form a 1D alternating chain in
a Ni(mnt)2 column through intermolecular Niꢁ ꢁ ꢁS, or
pꢁ ꢁ ꢁp interactions. Magnetic susceptibility measurements
for these complexes show that the overall magnetic behav-
ior for 1 and 2 indicates the presence of antiferromagnetic
interaction, but 1 exhibits an activated magnetic behavior
in the high-temperature (HT) region together with a Curie
tail in the low-temperature (LT) region.
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5. Supplementary material
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CCDC 636259 and 636260 contain the supplementary
crystallographic data for 1 and 2. These data can be obtained
free of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Acknowledgement
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The authors are grateful for the president’s foundation
of South China Agricultural University (No. 2005K092).
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