Synthesis, crystal structures and magnetic studies of dicyanamide bridged two new 1D copper(II) complexes

Article abstract of DOI:10.1016/j.ica.2007.05.034

Two new dicyanamide bridged 1D polynuclear copper(II) complexes [Cu(L¹){μ_1,5-N(CN)₂}]_n (1) [L¹H = C₆H₅C(O)NHN{double bond, long}C(CH₃)C₅H₄N] and [Cu(L²){μ_1,5-N(CN)₂}]_n (2) [L²H=C₆H₅C(O)CHC(CH₃){double bond, long}NCH₂CH₂N(CH₃)₂] have been synthesised and structures of both the complexes and their crystal packing arrangements have been established by X-ray crystallography. For complex 1, a tridentate hydrazone ligand (L¹H) obtained by the condensation of benzhydrazide and 2-acetylpyridine is used, whereas a tridentate Schiff base (L²H) derived from benzoylacetone and 2-dimethylaminoethylamine is employed for the preparation of complex 2. Variable temperature magnetic susceptibility measurement studies indicate there are weak antiferromagnetic interactions with J values -0.10 and -1.41 cm^-1 for 1 and 2, respectively.

Full text of DOI:10.1016/j.ica.2007.05.034

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Inorganica Chimica Acta 360 (2007) 4085–4092
www.elsevier.com/locate/ica
Synthesis, crystal structures and magnetic studies of
dicyanamide bridged two new 1D copper(II) complexes
a
a,
b
c
d
*
´
Soma Sen , Samiran Mitra , David L. Hughes , Georgina Rosair , Cedric Desplanches
a
Department of Chemistry, Jadavpur University, Kolkata 700 032, India
School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK
b
c
Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS, UK
´
d
`
´
Institut de Chimie de la Matiere Condensee de Bordeaux – CNRS, Universite Bordeaux 1, Avenue du Dr. Schweitzer, F-33608 Pessac, France
Received 14 March 2007; received in revised form 15 May 2007; accepted 21 May 2007
Available online 2 June 2007
Abstract
Two new dicyanamide bridged 1D polynuclear copper(II) complexes [Cu(L1){l1,5-N(CN)2}]n (1) [L1H = C6H5C(O)-
NHN@C(CH3)C5H4N] and [Cu(L2){l1,5-N(CN)2}]n (2) [L2H=C6H5C(O)CHC(CH3)@NCH2CH2N(CH3)2] have been synthesised and
structures of both the complexes and their crystal packing arrangements have been established by X-ray crystallography. For complex
1, a tridentate hydrazone ligand (L1H) obtained by the condensation of benzhydrazide and 2-acetylpyridine is used, whereas a tridentate
Schiff base (L2H) derived from benzoylacetone and 2-dimethylaminoethylamine is employed for the preparation of complex 2. Variable
temperature magnetic susceptibility measurement studies indicate there are weak antiferromagnetic interactions with J values ꢀ0.10 and
ꢀ1.41 cmꢀ1 for 1 and 2, respectively.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Copper(II) complexes; Dicyanamide bridging ligand; Crystal structures; Variable temperature magnetic studies
1. Introduction
and one amide nitrogen atoms (1b), end-to-end bridging
through two nitrile nitrogen atoms (1c), tris-monodentate
bridging of three metal atoms (1d) [11] and rarer l4-coordi-
nation where one of the two nitrile nitrogen atoms is coor-
dinated to two metal ions (1e).
The design and synthesis of polynuclear coordination
complexes, aimed at understanding the structural and
chemical factors that govern the exchange coupling
between paramagnetic centres, are of continuing interest
in biology, chemistry and physics [1]. The larger pseudoha-
lide ligand, dicyanamide [dca], has been extensively used
recently to generate a wide variety of polynuclear com-
pounds of different topologies and magnetic properties
partly due to the discovery of long-range magnetic ordering
in the M(dca)2 compounds [2,3]. The versatility of the dic-
yanamide as a ligand is well illustrated by its five structur-
ally characterised coordination modes shown in Scheme 1
[4–11], monodentate coordination through nitrile nitrogen
atom (1a), bis-monodentate bridging through one nitrile
Over the past years or so, several new binding modes
have been identified although the l1,5-mode seemingly
appears on a more regular basis and the transition metal
complexes with l1,5-dicyanamide bridging generally show
weak antiferromagnetic interaction [12–14]. A number of
studies have utilised with Cu2+ ions and a handful of
molecular and polymeric structures are known [15–17].
The versatility of the dicyanamide as bridging ligand,
prompted our group to report some dicyanamide bridged
di- and polynuclear transition metal complexes using Schiff
bases, amines, hydrazide, etc., as terminal ligands [18–22].
In continuation of this work, here we have synthesised
two dicyanamide bridged 1D polynuclear copper(II) com-
plexes [Cu(L1){l1,5-N(CN)2}]n (1) and [Cu(L2){l1,5-N(CN)2}]n
*
Corresponding author. Fax: +91 33 2414 6414.
E-mail address: smitra_2002@yahoo.com (S. Mitra).
0020-1693/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.05.034

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S. Sen et al. / Inorganica Chimica Acta 360 (2007) 4085–4092
the molar magnetic susceptibility, vM, for complexes 1 and
2 was measured on polycrystalline samples in the tempera-
ture range 2–300 K. Diamagnetic corrections were esti-
mated from Pascal tables and magnetic data were
corrected for diamagnetic contributions of the sample
holder.
N
N
N
N
N
N
µ1,3
µ1
1b
1a
2.2. Synthesis of ligands and metal complexes
2.2.1. [C6H5C(O)NHN@C(CH3)C5H4N] (L1H)
N
N
The ligand L1H was synthesised by the condensation of
benzhydrazide (1.36 g, 10 mmol) with 2-acetylpyridine
(1.12 ml, 10 mmol) in methanol (50 ml) according to the
procedure reported elsewhere [24]. The resulting light yel-
low liquid was used without further purification.
N
N
N
N
µ1,5
µ1,3,5
1c
1d
N
2.2.2. [C6H5C(O)CHC(CH3)@NCH2CH2N(CH3)2]
(L2H)
N
N
The ligand L2H was synthesised according to the litera-
ture procedure [19] by refluxing benzoylacetone (0.811 g,
5 mmol) and 2-dimethylaminoethylamine (5 mmol) in
25 ml of methanol. The resulting yellow liquid was used
without further purification.
µ1,1,3,5
1e
Scheme 1.
Caution! Perchlorate salts are potentially explosive and
should be used in small quantities and with much care.
(2) using a hydrazone (L1H=C6H5C(O)NHN@C(CH3)-
C5H4N) and a Schiff base (L2H=C6H5C(O)CHC(CH3)-
@NCH2CH2N(CH3)2) as coligand. The hydrazone ligand
is the condensation product of benzhydrazide and 2-acetyl-
pyridine, and the Schiff base (L2H) is obtained by the con-
densation of benzoylacetone and 2-dimethylaminoethylamine.
Using the same hydrazone ligand (L1H) very recently we
have reported two new pseudohalide bridged di- and poly-
nuclear copper(II) complexes [23]. The present paper
describes the synthesis, X-ray crystal structures, variable
temperature magnetic (VTM) susceptibility studies and
spectroscopic results of the two new Cu(II) complexes 1
and 2.
2.2.3. [Cu(L1){l1,5-N(CN)2}]n (1)
To a methanolic solution (20 ml) of copper perchlorate
hexahydrate (0.370 g, 1 mmol), the solution of the hydra-
zone ligand (L1H) (1 mmol) was added, followed by the
addition and constant stirring with a solution of sodium
dicyanamide (0.089 g, 1 mmol) in minimum volume of
water–methanol mixture. Dark green, hexagonal crystals
suitable for X-ray diffraction were formed after 9 days.
Crystals were collected and air dried. Yield – 62%. Anal.
Calc. for C16H12N6OCu: C, 52.19; H, 3.29; N, 22.83.
Found: C, 51.79; H, 3.22; N, 22.61%.
2.2.4. [Cu(L2){l1,5-N(CN)2}]n (2)
2. Experimental
To the solution of copper acetate monohydrate
(0.398 g, 1 mmol) in 20 ml methanol, was added, with
constant stirring, a methanolic solution of the ligand
L2H, followed by the solution of sodium dicyanamide
(0.178 g, 2 mmol, in water–methanol solvent). The result-
ing solution was kept at refrigerator temperature. Dark
green, hexagonal crystals suitable for X-ray diffraction
were obtained after 12 days. Crystals were collected and
air dried. Yield – 69%. Anal. Calc. for C16H19N5OCu:
C, 53.20; H, 5.30; N, 19.39. Found: C, 52.93; H, 5.12;
N, 19.21%.
2.1. Materials and physical measurements
Benzhydrazide, 2-acetylpyridine, benzoylacetone, 2-
dimethylaminoethylamine, copper(II) perchlorate hexa-
hydrate, copper(II) acetate monohydrate and sodium
dicyanamide (Fluka) were used as received. The solvents
used were of reagent grade.
The infrared spectra were recorded on a Perkin–Elmer
RX I FT-IR spectrophotometer with a KBr disc. The elec-
tronic spectra were recorded, in acetonitrile, on a Perkin–
Elmer Lambda 40 (UV–Vis) spectrophotometer. Elemental
analyses were carried out using a Perkin–Elmer 2400 II ele-
mental analyser. Magnetic susceptibility measurements for
the complexes 1 and 2 were carried out with a Quantum
Design MPMS-5S SQUID magnetometer under an applied
magnetic field of 5000 Oe. The temperature dependence of
2.2.5. X-ray crystallography
The diffraction equipment, each with Mo Ka radiation
˚
(k = 0.71073 A), used for each sample is listed with the
crystallographic data and the refinement results in Table
1. The structures of all the complexes were determined by
direct methods/procedures in SHELXS [25a], and refined by

S. Sen et al. / Inorganica Chimica Acta 360 (2007) 4085–4092
4087
Table 1
Crystallographic and refinement data for complexes 1 and 2
3. Results and discussion
Complex
1
2
3.1. Description of the crystal structures
Chemical formula
Formula weight
Crystal system
Space group
Z
C16H12N6OCu
367.86
monoclinic
P21/n
C16H19N5OCu
360.9
monoclinic
P21/n
3.1.1. [Cu(L1){l1,5-N(CN)2}]n (1)
An ORTEP representation of 1 with the atom num-
bering scheme is shown in Fig. 1 and the relevant bond
dimensions are included in Tables 2 and 3. The geometry
of the five-coordinate copper centres is very close to
square pyramidal (s = 0.0585) [s = jb-aj/60ꢁ, where b
and a are the two largest angles around the central atom;
s = 0 and 1 for the perfect square pyramidal and trigonal
bipyramidal geometries, respectively] [26]. About the Cu
atom, there are three donor atoms (N2O) of the coordi-
nated hydrazone ligand L1, in meridional mode in the
base plane, and two nitrogen atoms of two dicyanamide
(dca) ligands in the remaining base and apical sites. The
Cu(L1) units are connected through single end-to-end,
that is, l1,5-dca bridges, to form a linear chain arrange-
ment. The trans-base angles for N(10)–Cu(1)–
N(2) = 155.2(2)ꢁ and O(1)–Cu(1)–N(17) = 158.7(2)ꢁ are
smaller than expected in a regular square pyramid. As
depicted in Fig. 1, the bridging array Cu–NCNCN–Cu
adopts a ‘‘V’’-type conformation because of the sp2
hybridisation of the middle nitrogen atom of the dca,
where the C–N–C angle [C(100)–N(3)–C(101)] is
119.8(5)ꢁ [27]. ½NðCNÞ2ꢁꢀ has pseudo C2v symmetry with
average C–N and C@N bond lengths of 1.305(8) and
4
4
˚
a (A)
7.4904(7)
14.4190(15)
14.0422(14)
90
93.072(7)
90
1514.4(3)
100(2)
1.613
9.4995(14)
11.604(2)
15.228(5)
90
106.25(2)
90
1611.6(6)
293(2)
1.487
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Temperature (K)
Dcalc (Mg/m3)
Absorption coefficient (mmꢀ1
F(000)
)
1.458
748
1.367
748
Diffractometer used
Bruker–Nonius X8 Nonius CAD4
Apex-2
0.38 · 0.04 · 0.04
Crystal size (mm)
h Range for data collection (ꢁ) 2.83–27.54
Reflections collected
Independent reflections [Rint
Number of observed reflections 1654
Goodness-of-fit, S
R indices (all data)
0.48 · 0.43 · 0.33
2.2–27.5
4772
3688 [0.021]
3116
1.073
R1 = 0.025,
wR2 = 0.065
R1 = 0.025,
wR2 = 0.065
0.39 and ꢀ0.41
26346
3377 [0.181]
]
0.949
R1 = 0.145,
wR2 = 0.168
R1 = 0.0660,
wR2 = 0.149
0.59 and ꢀ1.95
Final R indices [I > 2r(I)]
Largest difference in peak and
ꢀ3
˚
hole (e A
)
˚
1.156(12) A, respectively, as commonly observed in
[N(CN)2]ꢀ anions [28,3,2,29–36]. The carbon atoms of
the dca ligand are sp hybridised, with almost linear
N–C–N angles (173.9(6) and 174.1(6)ꢁ) [37], while the
full-matrix least-squares methods in SHELXL [25b]. Carbon-
bonded hydrogen atoms were included in idealised posi-
tions and set to ride on the parent atoms.
Fig. 1. View of two units of a chain of 1, with atom labels. Displacement ellipsoids are shown at 50% probability level.

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S. Sen et al. / Inorganica Chimica Acta 360 (2007) 4085–4092
ping (strongly on one side, slightly on the other), the L1
ligands of the first chain (Fig. 2). Each phenyl ring thus
interacts with two pyridine rings (and vice versa), and the
overall effect is of infinite stacks of arene systems.
Table 2
˚
Molecular dimensions (bond lengths in A and angles in ꢁ) about the
copper atoms in complexes 1 and 2
1
2
Bond lengths
Cu1–O1
Cu1–N10
Cu1–N17
Cu1–N2
3.1.2. [Cu(L2){l1,5-N(CN)2}]n (2)
1.959(4)
1.924(4)
2.020(5)
1.967(4)
2.222(5)
Cu–O1
Cu–N4
Cu–N7
Cu–N9
Cu–N942
1.9099(12)
1.9527(14)
2.0514(14)
2.0245(15)
2.3913(17)
An ORTEP representation of 2 with atom numbering
scheme is shown in Fig. 3, and selected bond dimensions
are included in Tables 2 and 3. The copper centres are five
coordinated, with a pattern midway between trigonal bipy-
ramidal and square pyramidal (s = 0.442). About the Cu
atom, there are three donor atoms (N2O) of the coordi-
nated Schiff base ligand L2, in meridional mode, and two
nitrogen atoms of two dicyanamide (dca) ligands which
link to other Cu(L2) units through end-to-end bridging to
form a linear chain arrangement. In the trigonal bipyrami-
dal description, O(1) and N(7) are the axial ligand atoms,
and N(4), N(9) and N(942) form the equatorial plane; the
N(9)–Cu–N(4) angle is large, at 151.08(6)ꢁ. In the square
pyramidal arrangement, N942 is the apical atom, with a
Cu1–N1
Bond angles
N10–Cu1–O1
O1–Cu1–N17
O1–Cu1–N2
O1–Cu1–N1
N10–Cu1–N17
N10–Cu1–N2
N10–Cu1–N1
N2–Cu1–N17
N17–Cu1–N1
N2–Cu1–N1
79.57(17)
158.74(16)
99.03(16)
98.91(15)
79.84(18)
155.23(18)
106.89(16)
97.43(17)
92.08(16)
97.79(17)
O1–Cu–N4
O1–Cu–N7
O1–Cu–N9
O1–Cu–N942
N4–Cu–N7
N4–Cu–N9
N4–Cu–N942
N9–Cu–N7
N7–Cu–N942
N9–Cu–N942
93.21(5)
177.59(5)
89.18(6)
91.16(6)
85.04(6)
151.08(6)
103.72(6)
91.55(6)
90.87(6)
105.04(6)
˚
Cu–N distance of 2.391(2) A, much the longest Cu–N
Table 3
Selected bond dimensions (A and ꢁ) in the main chains of the L and L2
ligands and in the bridging ligands in complexes 1 and 2. E.s.ds are in
parentheses
1
bond; in the base plane, N4 and N9 have much larger
N94–Cu–L angles than O1 and N7, and the trans-base
angle for N4–Cu–N9, 151.08(6)ꢁ, is smaller than expected
in a regular square pyramid. As in 1, the bridging array
Cu–NCNCN–Cu adopts a ‘‘V’’-type conformation; the
central C–N–C angle [C91–N92–C93] is 124.1(2)ꢁ [27].
Similarly, [N(CN)2]ꢀ has pseudo C2v symmetry with aver-
˚
1
2
O(1)–C(2)
C(2)–N(9)
N(9)–N(10)
N(10)–C(11)
C(11)–C(12)
C(12)–N(17)
1.301(6)
1.326(6)
1.381(6)
1.295(6)
1.465(7)
1.358(6)
O(1)–C(1)
C(1)–C(2)
C(2)–C(3)
C(3)–N(4)
N(4)–C(5)
C(5)–C(6)
1.2831(19)
1.378(2)
1.422(2)
1.306(2)
1.466(2)
1.514(2)
C(6)–N(7)
1.480(2)
C(2)–O(1)–Cu(1)
O(1)–C(2)–N(9)
110.8(3)
C(1)–O(1)–Cu
O(1)–C(1)–C(2)
C(1)–C(2)–C(3)
N(4)–C(3)–C(2)
C(3)–N(4)–C(5)
N(4)–C(5)–C(6)
N(7)–C(6)–C(5)
C(6)–N(7)–Cu
126.42(11)
125.49(15)
125.67(15)
122.53(15)
120.30(14)
107.61(14)
110.16(14)
103.62(10)
124.3(5)
107.4(4)
123.0(4)
113.7(5)
113.7(5)
113.4(3)
C(2)–N(9)–N(10)
C(11)–N(10)–N(9)
N(10)–C(11)–C(12)
N(17)–C(12)–C(11)
C(12)–N(17)–Cu(1)
Complex 1, dca ligand
N(1)–C(1010)
N(3)–C(101)
N(3)–C(100)
N(2)–C(100)
2, dca ligand
N(9)–C(91)
C(91)–N(92)
N(92)–C(93)
1.144(6)
1.141(2)
1.300(2)
1.293(3)
1.312(6)
1.297(6)
1.168(6)
C(93)–N(94)
1.145(2)
C(1010)–N(1)–Cu(1)
N(100)–C(101)–N(3)
C(100)–N(3)–C(101)
N(2)–C(100)–N(3)
C(100)–N(2)–Cu(1)
162.7(4)
C(91)–N(9)–Cu
N(9)–C(91)–N(92)
C(93)–N(92)–C(91)
N(94)–C(93)–N(92)
C(93)–N(94)–Cu2
160.55(14)
171.49(19)
124.09(18)
172.8(2)
174.1(6)
119.8(5)
173.9(6)
148.0(4)
170.08(16)
Symmetry operation used to generate equivalent atoms for 1: x + 1/2,
ꢀy + 1/2, z + 1/2.
Symmetry operation used to generate equivalent atoms for 2: x + 1/2,
ꢀy + 1/2, z + 1/2.
C–N–Cu angles, 148.0(4) and 162.7(4)ꢁ, deviate consider-
ably from linearity.
The L1 ligands in each chain are separated by one unit
cell along the a-axis. A second chain, related by an inver-
sion centre, has its L1 ligands lying parallel to, and overlap-
Fig. 2. View of two chains of 1, showing the overlap of phenyl with
pyridine rings.

S. Sen et al. / Inorganica Chimica Acta 360 (2007) 4085–4092
4089
Fig. 3. View of two units in a chain of 2, with atom labels. Displacement ellipsoids are shown at 50% probability level.
age C–N and C@N bond lengths of 1.297(3) and 1.143(2)
ꢀ
˚
A, respectively, as commonly observed in [N(CN)2]
anions [28,3,2,29–36]. The carbon atoms of the dca ligand
are sp hybridised and almost linear, with N–C–N angles
171.5(2) and 172.8(2)ꢁ [37], while the C–N–Cu angles,
160.55(14) and 170.1(2)ꢁ, deviate slightly from linearity.
Each polymeric chain, which connects units related by
glide-plane symmetry, runs parallel to the [101] cell vector
(Fig. 4). The chain is linked to adjacent, parallel chains on
two sides through the overlap of phenyl ring planes,
which are related by centres of symmetry, and these p–p
interactions link the chains in sheets throughout the
crystal.
3.2. Infrared spectra
The infrared spectra of complexes 1 and 2 display
absorption bands at ca. 1563 cmꢀ1, which can be assigned
to the C@N stretching frequency of the coordinated ligand
L1/L2 [38]. The solid state spectra of complexes 1 and 2
depict several mCꢀN bands, at 2298, 2244, 2174 cmꢀ1 for 1,
and 2383, 2229, 2167 cmꢀ1 for 2, which are attributed to
m
sym + masym (CN), masym (CN) and msym(CN) modes of the
bridging dicyanamide ligand respectively. All data are in
good agreement with the literature [39–43]. The ligand
coordination to the metal centre is substantiated by two
bands appearing for each complex, at 422, 314 (1) and
462, 373 cmꢀ1 (2) attributable to mCu–N and mCu–O
respectively.
,
Fig. 4. View of a sheet of interconnected chains of 2, showing the overlap
of pairs of phenyl rings.

4090
S. Sen et al. / Inorganica Chimica Acta 360 (2007) 4085–4092
0.46
0.44
3.3. Electronic spectra
The electronic spectral data for the complexes in acetoni-
trile are in good agreement with their geometries. The UV
absorption bands exhibit a charge transfer transition (CT)
in the range 350–420 nm for Cu(II) complexes and may be
assigned to the ligand-to-metal charge transfer transition
for each of the compounds 1 and 2. The spectrum of complex
1 displays a broad band at 642 nm, consistent with the
expected five-coordinated geometry. A broad band with a
shoulder at 746 nm appeared in the spectrum of 2, also sup-
porting the geometry of this complex [44].
)
-1
l
o
0.42
0.4
m
K
m
3
(c
0.38
0.36
0.34
0.32
T
M
χ
0
50
100
150
T (K)
200
250
300
3.4. Magnetic studies
Fig. 6. Experimental (h) and calculated (—-) temperature dependence of
The temperature dependence of vMT for 1 and 2 are
shown in Figs. 5 and 6, respectively. Due to the chain struc-
ture of the complexes, the model of equally spaced
vMT for 2.
copper(II) ions has been used. The spin Hamiltonian in
P
The weak coupling inside the chain is due to the longer
zero-field is H ¼ ꢀJ nꢀ1SA ꢂ SA where the summation
i
i¼1
iþ1
distance between the copper(II) ions as dicyanamide acts as
a l1,5-bridging ligand. The weak interaction can also be
explained by the fact that one end of the dca bridge is in
the apical position of the square pyramidal copper. The
magnetic orbital ðdx2ꢀy2 Þ being perpendicular to that direc-
tion, no overlap between magnetic orbitals is expected.
This explains the low absolute value of J for both com-
plexes 1 and 2.
runs over the n sites of the chain. When n tends to infinity,
there is no analytical method to determine the magnetic
susceptibility. However, the results can be fitted using the
numerical expression for J < 0 [45]
Ng2b2
vMT ¼
k
0:25 þ 0:074975x þ 0:075235x2
ꢃ
with x
1:0 þ 0:9931x þ 0:172135x2 þ 0:757825x3
4. Conclusion
¼ ꢀJ=kT:
Two new l1,5-dicyanamide bridged 1D copper(II) poly-
mer with l1,5-dicyanamide containing a tridentate hydra-
zone (L1H) and a tridentate Schiff base (L2H) as coligand
respectively, have been synthesised. In 1, the copper(II)
centres exhibit square pyramidal coordination geometry
while the copper(II) centres in 2 had intermediate square
pyramidal-trigonal bipyramidal coordination geometry.
Electronic spectra of the complexes support their geome-
tries as established from X-ray analysis. Magnetic studies
indicate complexes 1 and 2 exhibit weak antiferromagnetic
interactions.
For 1, the best fit was obtained with a Lande factor g of
2.11, isotropic interaction parameter J = ꢀ0.10 cmꢀ1. This
small value is in line with a similar reported structure [13].
The best fit for 2 was obtained for Lande factor g = 2.17
and isotropic interaction parameter J = ꢀ1.41 cmꢀ1. The
small value of J is in line with some previously reported
ones [46].
0.420
0.418
5. Supplementary material
)
-1
l
o
0.416
0.414
0.412
0.410
0.408
m
CCDC 615284 and 615285 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/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
K
3
m
(c
T
M
χ
0
50
100
150
200
250
300
Acknowledgement
T (K)
We acknowledge the financial assistance to S. Sen from
the CSIR (New Delhi, India).
Fig. 5. Experimental (h) and calculated (—-) temperature dependence of
MT for 1.
v

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