Ferro- and antiferromagnetic interactions of layer-structured basic copper compounds as studied by solid-state high-resolution deuterium NMR

Article abstract of DOI:10.1016/S0277-5387(03)00174-8

Magnetic local structure of a ferromagnetic layer-structured basic copper compound Cu₂(OD)_1.96(C₄H₆ (COO)₂)_1.020.07D₂O with dicaboxylate anion was examined by solid-state high-resolution deuterium NMR above 200 K. The magnetic interaction in a copper layer was probed by the isotropic D NMR shift of OD^- ions. Only one strong signal was observed for the OD^- ions of Cu₂(OD)_1.96(C₄H₆ (COO)₂)_1.020.07D₂O, while more than two signals corresponding to different magnetic chains of Cu²⁺ ions in a layer were observed for most of Cu₂(OD)₃X where X was univalent anion. A ferromagnetic exchange interaction J = +71 K within a copper layer was estimated from the temperature dependence of the isotropic D NMR shift by assuming an one-dimensional Heisenberg model. A layer-structured compound Cu₂(OH)₃(SCN) with non-oxygen atom coordination for bridging copper ions was synthesized by anion exchange reaction. The magnetic susceptibility measurement indicates that a weak ferromagnetic interaction dominates in the high temperature region and a weak antiferromagnetic interaction appears in the low temperature region.

Full text of DOI:10.1016/S0277-5387(03)00174-8

Polyhedron 22 (2003) 1995ꢃ2001
/
www.elsevier.com/locate/poly
Ferro- and antiferromagnetic interactions of layer-structured basic
copper compounds as studied by solid-state high-resolution
deuterium NMR
Kunio Morii, Goro Maruta, Sadamu Takeda *
Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
Received 6 October 2002; accepted 19 December 2002
Abstract
Magnetic local structure of a ferromagnetic layer-structured basic copper compound Cu
with dicaboxylate anion was examined by solid-state high-resolution deuterium NMR above 200 K. The magnetic interaction in a
2
(OD)1.96(C
4
6
H (COO)
2
)
1.02
×
/
2
0.07D O
ꢀ
ꢀ
copper layer was probed by the isotropic D NMR shift of OD ions. Only one strong signal was observed for the OD ions of
2
ꢁ
Cu
2
(OD)1.96(C
H
4 6
(COO)
2
)
1.02 0.07D
2
O, while more than two signals corresponding to different magnetic chains of Cu ions in a
71 K within
a copper layer was estimated from the temperature dependence of the isotropic D NMR shift by assuming an one-dimensional
Heisenberg model. A layer-structured compound Cu (OH) (SCN) with non-oxygen atom coordination for bridging copper ions was
layer were observed for most of Cu (OD) X where X was univalent anion. A ferromagnetic exchange interaction Jꢂ
/
ꢁ
/
2
3
2
3
synthesized by anion exchange reaction. The magnetic susceptibility measurement indicates that a weak ferromagnetic interaction
dominates in the high temperature region and a weak antiferromagnetic interaction appears in the low temperature region.
#
2003 Elsevier Science Ltd. All rights reserved.
Keywords: Layer-structured basic copper compound; Local magnetic structures; Local magnetic interactions; Hyperfine coupling of ODꢀ ions;
Solid-state high-resolution deuterium NMR
1
. Introduction
exchange reaction by stirring the suspended powder
crystals of basic copper acetate Cu (OH) CH COO×
/
2
3
3
Botallackite-type
basic
copper
compounds
H O in MX aqueous solutions, where M is an alkali
2
Cu (OH) X (Xꢂ
/
exchangeable univalent anion) exhibit
a layered structure as schematically depicted in Fig. 1
1,2]. Hydroxide ions and exchangeable anion X bridge
metal ion [3ꢃ6]. The bulk magnetism of Cu (OH) X
/
2
3
2 3
sensitively depends on X. The magnetism also varies
with different intercalation structures exhibiting various
interlayer distances even for the same exchangeable
[
the copper ions to form infinite layers. Two chemically
distinct copper ions lie in different distorted-octahedral
coordination environments, i.e., Cu[(OH) X ] and
anion X, particularly for aliphatic mono-carboxylate
ꢀ
4
2
C H2nꢁ1COO [7]. We have demonstrated that the
n
Cu[(OH) X(OH)]. Each copper ion forms an one-
4
magnetic interactions within the copper layer could be
approximated by a sum of one-dimensional magnetic
dimensional chain and the two distinct chains are
alternately connected to form a layer, in which all
copper ions sit on the same plane constructing a
nonequilateral planar triangular arrangement in the
chains in the high temperature region [8ꢃ11]. The
/
copper chain A in Fig. 1 shows ferro- and antiferro-
magnetic interactions depending on the anion X, while
the copper chain B mostly exhibits antiferromagnetic
interaction. The antiferromagnetic interaction domi-
nates the bulk magnetism for many compounds
Cu (OH) X. It was reported, however, in recent years
case of a simple compound such as Cu (OH) Br [1].
2
3
Various anions X can be incorporated by anion-
2
3
*
Corresponding author. Tel.: ꢁ
841.
E-mail address: stakeda@sci.hokudai.ac.jp (S. Takeda).
/
81-11-706-3505; fax: ꢁ81-11-706-
/
that a compound with dicaboxylate (trans-3-hexenedio-
ate) anion showed ferromagnetic ordering at 13 K [6].
4
0
277-5387/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0277-5387(03)00174-8

1996
K. Morii et al. / Polyhedron 22 (2003) 1995ꢃ2001
/
diso ꢂdFermi ꢁdPseudo ꢁd
(1)
S(Sꢁ1)F(J; T)
dia
ꢀ
ꢁ
mB AFermi gxx ꢁ gyy ꢁ gzz
dFermi ꢂ3
k T g =2p
3
B
D
(
2)
2
B
m
2
zz
2
xx
2
yy
2
dPseudo ꢂ1
f[2g ꢀ(g ꢁg )](3 cos uꢀ1)
3
8k Tr
2
B
2
2
ꢀ
3(g ꢀg ) sin u cos 2VgS(Sꢁ1)F(J; T)
yy
xx
(
3)
Electron spin induced on the deuteron by electron spins
2
ꢁ
of Cu
NMR resonance line, whereas anisotropy of the g-
ions causes a Fermi contact shift of the D
2
ꢁ
tensor of Cu
ion gives a pseudo contact shift. Since
Fig. 1. Schematic view of layered structure and intra-layer structure of
Cu (OH) CH O. Two distinct copper chains A and B with
COO×
different coordination structures are illustrated. Water molecules are
the temperature dependence of dPseudo is the same as
that of dFermi, Eqs. (2) and (3) can be reduced to the
following formula:
2
3
3
/
H
2
not shown in this figure.
mB
AD
dFermi ꢁdPseudo ꢂ3
S(Sꢁ1)F(J; T)
(4)
This led us to investigate the local magnetic structure of
the deuterated analogue by means of the solid-state
high-resolution deuterium NMR (D NMR) spectro-
scopy to elucidate the magnetic interactions within the
layer in a microscopic viewpoint.
k T g =2p
B
D
The coefficient A is the hyperfine coupling constant of
D
the nucleus D in hertz unit [14], which consists of Fermi
and pseudo contact terms. The function F(J, T) gauges
In many cases, the oxygen atoms of exchangeable
anions bridge the copper ions within a layer. An effort
to employ non-oxygen atoms for bridging the copper
ions is interesting in a viewpoint of modifying the
magnetic coupling among the copper ions [11]. Thio-
cyanate ion was used to form the layered structure
compound Cu (OH) (SCN).
the interactions among the Sꢂ1/2 electron spins of the
/
2
ꢁ
Cu ions. The anisotropy of the g-tensor is often small
for copper complexes. The contribution of the pseudo
contact term to the hyperfine coupling constant AD in
Eq. (4) was estimated to be approximately 0.2 MHz for
an analogous compound Cu (OD) (NO ) [8,15]. Magic
2
3
3
2
3
angle spinning deuterium NMR (MAS D NMR) spectra
were measured by a similar method described in Ref.
[
14] at the resonance frequency of 46.1 MHz and at the
magic angle spinning speed of 8ꢃ10 kHz with a Bruker
/
2
. Method and experiment
DSX300 spectrometer. The thermometer of the MAS
NMR probe and an effect of spinning speed on
temperature increase were carefully calibrated by using
2.1. Solid-state high-resolution deuterium NMR and
magnetic susceptibility measurements
2
07
Pb NMR shift of Pb(NO ) [16]. The precision of the
3
2
temperature measurement after calibration was 92 K.
/
Since an ODꢀ ion bridges copper ions and mediates
exchange interactions among them, the paramagnetic D
All D NMR shifts were measured from the external
second reference of CD OD (CD : 3.35 ppm).
3
3
ꢀ
NMR shift of the OD ion, which is induced by the
Direct current magnetic susceptibility was measured
with SQUID magnetometer (Quantum Design MPMS
hyperfine coupling between the deuteron of ODꢀ and
the electron spins of copper ions, is an excellent probe
for elucidating the local magnetic structures and the
local magnetic interactions in a microscopic view point.
The high-speed magic angle spinning technique removes
the quadrupole coupling of deuteron and averages the
anisotropy of the dipolar interaction between deuteron
and electron spins to provide an isotropic shift of the D
NMR absorption line. The observed isotropic shift
consists of the Fermi contact term, the dipolar interac-
tion term (pseudo contact) and the temperature inde-
pendent diamagnetic term (chemical shift) as follows
5) at an external magnetic field of 1 T.
2.2. Sample preparation
The preparation method of Cu (OD) (C H -
2
1.96
4
6
(COO)2)1.02
compound reported in Ref. [6]. The starting compound
Cu (OH) CH COO×H O was synthesized by titration of
×
/
0.07D O is similar to that of the protonated
2
/
2
3
3
2
copper acetate by sodium hydroxide [17]. Powder
crystals of Cu (OH) CH COO×H O (0.5 mmol) were
/
2
3
3
2
[
12,13]:
suspended and stirred in 15 ml of 0.25 M heavy water

K. Morii et al. / Polyhedron 22 (2003) 1995ꢃ
/2001
1997
solution of sodium salt of trans-b-hydromuconic (trans-
-hexenedioic) acid Na C H (COO) at room tempera-
(26.36). Therefore, the layer-structured compound
Cu (OH) SCN can be obtained by controlling the
reaction time. The same preparation procedure was
3
2
4
6
2
2
3
ture for 1 day. Repeating once the treatment of the
reaction product with a fresh solution for 2 days
completed the exchange reaction. The green powder
microcrystalline sample was washed by heavy water and
dried in desiccator. Elemental analysis gave C: 24.14%
conducted with employing D O to obtain the deuterated
2
analogue. However, the MAS D NMR signal was not
detected at present.
and H(D): 2.69%, indicating
a
formula of
Cu (OD) (C H (COO) ) 0.07D O, which is simi-
×
/
3. Results and discussion
2
1.96
4
6
2 1.02
2
lar to the previous report for the protonated compound
6]. The powder X-ray diffraction showed strong (0 0 l)
lines (l 54) as shown in Fig. 2, indicating that the
[
3.1. Magnetic susceptibility measurement
/
layered structure was maintained and the interlayer
distance was enlarged by anion exchange to 1.02 nm
from 0.93 nm of starting compound.
Thiocyanate ion was incorporated in the layered
structure similarly. Powdered crystals of the starting
Fig. 4(a) shows the magnetic susceptibility xT of
Cu (OH) SCN. A very weak ferromagnetic interaction
dominates in the high temperature region and a weak
antiferromagnetic interaction appears in the low tem-
2
3
perature region. The Weiss temperature u
ꢂ
/
ꢁ7 K was
/
W
compound Cu (OH) CH COO×
/
H O (2.35 mmol) were
2
estimated from the high temperature region of 1/x vs. T
above 150 K. Strong antiferromagnetic interactions
2
3
3
suspended and stirred in 30 ml of 1.58 M normal
aqueous solution of sodium thiocyanate at room
temperature. The acetate ion was gradually exchanged
by thiocyanate ion while maintaining the layered
structure, which was checked by powder X-ray diffrac-
dominates in a compound Cu
with an interlayer distance of 2.49 nm [10] as depicted in
Fig. 4(b). The Weiss temperature u 163 K of this
(OD) (CH (CH ) COO)
2
3 3 2 6
ꢂ
/
ꢀ
/
W
compound was estimated in the high temperature region
above 150 K. On the other hand, for the complex
tion at every 2 h as depicted in Fig. 3(aꢃ
d0 0 1 0.93 nm and its higher diffraction peaks of
starting compound gradually disappeared and a new
peak at d0 0 1 1.12 nm and its higher diffraction (0 0 l)
with l 53 increased until the reaction period reached 6
/d). The peak at
ꢂ
/
Cu
netic interaction dominates the bulk magnetism as
shown in Fig. 5. The Weiss temperature u of this
compound is ꢁ49 K. The ferromagnetic behavior is
2
(OD)1.96(C
4
H
6
(COO)
2
)
1.02
×
/
0.07D O, a ferromag-
2
ꢂ
/
W
/
/
h. At this stage, the starting compound almost com-
pletely changed to a new layer structured compound as
shown in Fig. 3(d). Elemental analysis gave C, 5.38%
very similar to that of protonated compound reported
by Hornick et al. [6]. The maximum value of xT of the
present deuterated compound is approximately 1/20
times smaller than the reported value for the protonated
one. The inter layer distance 1.02 nm of deuterated
(
Calc. 5.09); H, 1.98% (1.28); N, 6.18% (5.93) and S,
2.9% (13.58), indicating a formula Cu (OH) SCN. A
1
2
3
longer reaction period induced a reduction of Cu(II)
ions to form a-Cu(I)SCN and after 45 h of stirring the
powder crystals almost completely transformed to a-
Cu(I)SCN, which was confirmed by powder X-ray
diffraction shown in Fig. 3(f) and elemental analysis,
C, 9.87% (Calc. 9.88); N, 11.23% (11.52) and S, 25.14%
compound Cu
incides with that of protonated one Cu
(C (COO) 0.22H O [6].
2
(OD)1.96(C
4
H
6
(COO)
2
)
1.02 2
×
/
0.07D O co-
(OH)1.92-
2
H
6
)
×
/
4
2
1.04
2
3.2. Solid-state high-resolution deuterium NMR
To investigate the local magnetic structures within a
layer in a microscopic view point, solid-state high-
resolution deuterium NMR spectrum was measured
with high-speed magic angle spinning for Cu (OD)1.96-
2
(
C H (COO) )
4
×
/
0.07D O. Fig. 6(a) shows a whole
6
2 1.02 2
range of the MAS D NMR spectrum measured at a
spinning rate of 8 kHz at 313 K. There are many
spinning side bands spread over 8000 ppm around an
isotropic shift at ꢀ298 ppm. The isotropic shift was
/
distinguished by use of different spinning speed as usual.
The envelope of all the spinning side bands corresponds
to the powder line shape of the hydroxide deuterium
atom and the whole spectrum shape is governed by a
quadrupole interaction of the hydroxide deuterium and
an anisotropic dipole interaction between the deuteron
and electron spins of the copper ions. Fig. 6(b) depicts a
magnified region near the isotropically shifted signal.
Fig. 2. Powder X-ray diffraction pattern of deuterated compound
Cu
tion.
2
(OD)1.96(C
4
H
6
(COO)
2
)
1.02 2
×0.07D O measured with Cu Ka irradia-
/

1998
K. Morii et al. / Polyhedron 22 (2003) 1995ꢃ2001
/
Fig. 3. Reaction time dependence of the powder X-ray diffraction pattern: (a) starting material Cu
starting material was suspended and stirred in aqueous NaSCN solution at room temperature for 2 h, (c) 4 h, (d) 6 h, (e) 18 h and (f) 45 h. The
diffraction pattern of Cu (OH) CH O gradually disappeared and the diffraction of Cu (OH) SCN increased within 6 h as shown in (aꢃd).
COO×
Longer reaction period induced a reduction of the Cu(II) ion to form a-Cu(I)SCN as depicted in (e) and (f).
2
(OH)
3
CH
3
2
COO×/H O, (b) powder crystal of
2
3
3
/
H
2
2
3
/
Only one strong signal was observed for the ODꢀ ions
of Cu (OD) (C H (COO) ) 0.07D O, while more
than two signals corresponding to chemically different
hydroxide ion a is linked to the magnetic orbitals
in Cu-chain A, it dominantly detects the magnetic
interaction in the one-dimensional Cu-chain A. When
×
/
d
x ꢀy
2
/
2
2
1.96
4
6
2 1.02
2
ꢀ
OD ions, i.e., a and b depicted in Fig. 1, of different
the anion X is exchanged, the magnetic local structure
around the hydroxide ion a varies largely in comparison
2
ꢁ
magnetic chains of Cu
for most of the Cu (OD) X compounds, where X is
ions in a layer were observed
ꢀ
with b as previously demonstrated for Xꢂ
/
NO ,
2
3
3
ꢀ
ꢀ
univalent anion. For example, four isotropically shifted
signals with a relative intensity of 2:1:2:1 corresponding
HCOO , and C H COO [8,9]. This behavior suggests
6 5
that a one-dimensional character is strong for the
dominant magnetic interaction among copper ions in
the high temperature region. Thus, we assumed a one-
ꢀ
to b, a, b?, a? OD ions of different copper chains were
observed for Cu (OD) (CH (CH ) COO) with an inter
2
3
3
2 6
layer distance of 2.49 nm as shown in Fig. 7 [10]. All the
four signals showed different temperature dependencies
of their shifts as depicted in Fig. 8(a). Since the
dimensional Sꢂ1/2 Heisenberg model. In this case, the
term F(J, T) in Eq. (4) can be approximated by a Pade´
expansion series [18],
/

K. Morii et al. / Polyhedron 22 (2003) 1995ꢃ
/2001
1999
Fig. 6. MAS D NMR spectrum of Cu
0
2
(OD)1.96(C
4
H
6
(COO)
2
)
.07D O measured at spinning speed of 8 kHz at 313 K, (a) full range
1.02
×
/
2
2 3
Fig. 4. Magnetic susceptibility xT of Cu (OH) SCN (a) and
spectrum covering all of the spinning side bands and (b) magnified
region near the isotropically sifted signal. The isotropic shift is marked
with star and all other peaks are spinning side bands.
Cu
2
(OD) (CH
3
3
2
(CH )
6
COO) (b) as a function of temperature.
2
F(J; T)ꢂ[(1ꢁ5:7979916K ꢁ16:902653K
3
4
ꢁ
ꢁ
29:376885K ꢁ29:832959K
of ODꢀ ions gave the best fitting curves depicted in Fig.
5
14:036918K )=(1ꢁ2:7979916K
8
(a), where we fixed the diamagnetic shift ddia of the
2
3
ꢁ
ꢁ
7:0086780K ꢁ8:6538644K
hydroxide ions to 10 ppm as found for many diamag-
netic compounds. The derived values of the exchange
interaction J and the hyperfine coupling constants AD
are listed in Table 1. A change of ddia from 5 to 15 ppm
4
4:5743114K )]
2=3
(5)
where KꢂJ/(2k T). The above function can be used for
ferro- and antiferromagnetic interactions and is con-
venient for analyzing a variety of Cu (OD) X com-
pounds. Least-squares fittings of the observed
temperature dependence of the isotropic NMR shifts
/
B
gave a change of 9
and A? are largely antiferromagnetic for Cu
(CH (CH COO) as well as the Cu-chains B and B?,
whereas the Cu-chain A is ferromagnetic for Xꢂ
/
2 K for J values. The Cu-chains A
(OD) -
3
2
3
2
)
2 6
3
ꢀ
3
/
NO
as we reported previously [8]. The
magnetic interaction of CuÃOHÃCu is known to be
ꢀ
and HCOO
/
/
very sensitive to its angle, varying between ferro- and
antiferromagnetic around 988 in the case of dinuclear
Fig. 7. Four isotropically shifted signals of MAS D NMR spectrum of
Fig. 5. Magnetic susceptibility xT of Cu
.07D O as a function of temperature.
2
(OD)1.96(C
4
H
6
(COO)
2
)
1.02
×
/
2 3 3 2 6
Cu (OD) (CH (CH ) COO) measured at 303 K with the spinning
speed of 10 kHz.
0
2

2000
K. Morii et al. / Polyhedron 22 (2003) 1995ꢃ2001
/
from the elemental analysis, one of the three hydroxide
ions of Cu (OD) X, where X is univalent anion, is
2
3
exchanged with an oxygen atom of divalent
ꢀ
C H (COO ) anion to link the upper and lower layers
4
6
2
shown in Fig. 1. The hydroxide ion a may almost be
exchanged, since one of the three coordination bonds of
this hydroxide ion is axial coordination to the copper
ion as depicted in Fig. 1 and this bond is weaker than
the planar coordination bonds. All the three coordina-
tion bonds of X are axial coordination and therefore the
anion X can be easily exchanged at first. On the other
hand, all the three coordination bonds of the hydroxide
ion b provide a planar coordination for the copper ions.
The hydroxide ions b strongly coordinate to the copper
ions and remain in the copper layer after the exchange
ꢀ
reaction. Thus the observed signal of OD ion was
assigned to the hydroxide ion b shown in Fig. 1. Then
we assumed a one-dimensional Heisenberg model for
the analysis of the temperature dependence of the shift
of this signal as in the case of Cu (OD) X. The fitting of
2
3
Eq. (4) with use of a function F(J, T) of Eq. (5) is shown
in Fig. 8(b). All the values of the diamagnetic shift
ddia
interaction Jꢂ
constant A ꢂ
the least-squares fitting, indicating a ferromagnetic
coupling within the copper chain B in the layer. When
we fixed the diamagnetic shift ddia of the hydroxide ions
ꢂ
/
19
/
10 ppm of the hydroxide ions, the exchange
71920 K and the hyperfine coupling
1.4090.13 MHz were estimated from
/
ꢁ
/
/
Fig. 8. Temperature dependence of isotropic shift of MAS D NMR of
Cu (OD) (CH (CH COO) (a) and of Cu (OD)1.96(C (COO)
.07D O (b).
/
ꢀ
/
/
D
2
3
3
2
)
6
2
4
H
6
2
)
1.02
/
×
0
2
to 10 ppm, we obtained the values of Jꢂ
A ꢂ 1.5090.01 MHz (Table 1). This result for
Cu (OD) (C H (COO) ) 0.07D O with the diva-
/
ꢁ
/
5792 K and
/
/
ꢀ
/
/
D
copper complexes [19]. Although it is not established
whether the same relation holds for the infinite copper
chains, the angles around 988 were found for
Cu (OH) NO [2]. The magnetic interaction within the
×
/
2
1.96
4
6
2 1.02
2
ꢀ
lent anion C H (COO ) linking the upper and the
4
6
2
lower layers is very different from the case of
Cu (OD) X, in which the copper chain B always shows
2
3
3
2
3
copper chain A seems to vary largely by exchanging the
Cu in this chain
can be sensitively affected by the property of the anion
an antiferromagnetic interaction for univalent acid
anions X. A significant deformation of CuÃODÃCu
angle in the copper chain B is considered to occur in this
system. The magnetic interaction in the copper chain A
could not be determined at present, since the hydroxide
ion a, which mainly probes the magnetic interaction
within the copper chain A, was lost in this compound.
anion X, since the angle of CuÃ
/
OHÃ
/
/
/
X.
For Cu (OD) (C H (COO) )
6
×
/
0.07D O, which
2
1.96
4
2 1.02 2
shows ferromagnetic behavior as a bulk magnetism,
only one signal was observed for ODꢀ ions. Judging
Table 1
Magnetic interactions deduced from solid-state high-resolution deuterium NMR spectrum
Compound (interlayer distance)
Hydroxide ion
HFCC A
D
(MHz)
Magnetic interaction J (K)
Cu
(2.49 nm)
2
(OD) (CH
3
3
2
(CH )
6
COO)
b
a
b?
a?
ꢀ
/
1.01
1.15
1.62
1.51
ꢀ
/
209
201
122
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ/
ꢀ
/44
Cu
(1.02 nm)
2
(OD)1.96(C
4
H
6
(COO)
2
)
1.02
×
/
0.07D
2
O
b
ꢀ
/
1.40
ꢁ
/
71
a
a
(ꢀ1.50)
/
(ꢁ57)
/
a
See the text.

K. Morii et al. / Polyhedron 22 (2003) 1995ꢃ
/2001
2001
[
9] S. Takeda, M. Arai, G. Maruta, K. Yamaguchi, Mol. Cryst. Liq.
Cryst. 341 (2000) 369.
10] S. Takeda, M. Arai, G. Maruta, Mol. Cryst. Liq. Cryst. 343
2000) 77.
11] M. Kurmoo, Mol. Cryst. Liq. Cryst. 342 (2000) 167.
Acknowledgements
[
[
This research was supported by The Mitsubishi
Foundation and by grant-in-aid for Scientific Research
on Priority Areas (A) from the Ministry of Education,
Culture, Sports, Science and Technology of Japan.
(
[12] R. Kurland, B.R. McGervey, J. Magn. Reson.
86.
13] J.P. Jesson, in: G.N. La Mar, W.DeW. Horrocks, Jr., R.H. Holm
Eds.), NMR of Paramagnetic Molecules, Academic Press, New
2 (1970)
2
[
[
(
York, 1973.
14] G. Maruta, S. Takeda, R. Imachi, T. Ishida, T. Nogami, K.
Yamaguchi, J. Am. Chem. Soc. 121 (1999) 424.
References
[
1] H.R. Oswald, Y. Iitaka, S. Locchi, A. Ludi, Helv. Chim. Acta 44
1961) 2103.
[15] M. Atanasov, N. Zotov, C. Friebel, K. Petrov, D. Reinen, J. Solid
State Chem. 108 (1994) 37.
(
2] H. Effenberger, Z. Krist. 165 (1983) 127.
[
[
[
[
[
[
[16] P.A. Beckmann, C. Dybowski, J. Magn. Reson. 146 (2000)
379.
3] S. Yamanaka, T. Sako, M. Hattori, Chem. Lett. (1989) 1869.
4] W. Fujita, K. Awaga, Inorg. Chem. 35 (1996) 1919.
5] W. Fujita, K. Awaga, J. Am. Chem. Soc. 119 (1997) 4563.
6] C. Hornick, O. Rabu, M. Drillon, Polyhedron 19 (2000) 259.
7] V. Laget, C. Hornick, P. Rabu, M. Drillon, J. Mater. Chem. 9
[17] A. Jim e´ nez-Lop e´ z, E. Rodr ´ı guez-Castell o´ n, P. Olivera-Pastor, P.
Maireles-Torres, A.A.G. Tomlinson, D.J. Jones, J. Rozi e` re, J.
Mater. Chem. 3 (1993) 303.
[18] G.A. Baker, Jr., G.S. Rushbrooke, H.E. Gilbert, Phys. Rev. A
135 (1964) 1272.
(1999) 169.
[
8] S. Takeda, G. Maruta, T. Terasawa, N. Fukuda, K. Yamaguchi,
Mol. Cryst. Liq. Cryst. 335 (1999) 11.
[19] O. Kahn, Molecular Magnetism, VCH Publishers, Cambridge,
1993, p. 159.