Syntheses, structures, and magnetic properties of heterobimetallic complexes based on tetracyanometallic building blocks

Article abstract of DOI:10.1016/j.ica.2008.02.036

Two tetracyanometalate building blocks, [Fe(5,5′-dmbipy)(CN)₄]^- (2) and [Fe(4,4′-dmbipy)(CN)₄]^- (3) (5,5′-dmbipy = 5,5′-dimethyl-2,2′-bipyridine; 4,4′-dmbipy = 4,4′-dimethyl-2,2′-bipyridine), and two cyano-bridg

Full text of DOI:10.1016/j.ica.2008.02.036

Available online at www.sciencedirect.com
Inorganica Chimica Acta 361 (2008) 2901–2908
www.elsevier.com/locate/ica
Syntheses, structures, and magnetic properties of
heterobimetallic complexes based on
tetracyanometallic building blocks
He-Rui Wen a,b,*, Cai-Feng Wang b, Zi-Yi Du a, Jing-Lin Zuo b,*
a College of Chemistry and Life Science, Gannan Normal University, Ganzhou, Jiangxi 341000, PR China
b Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, PR China
Received 4 December 2007; received in revised form 15 February 2008; accepted 19 February 2008
Available online 26 February 2008
Abstract
Two tetracyanometalate building blocks, [Fe(5,50-dmbipy)(CN)4]ꢀ (2) and [Fe(4,40-dmbipy)(CN)4]ꢀ (3) (5,50-dmbipy = 5,50-dimethyl-
2,20-bipyridine; 4,40-dmbipy = 4,40-dimethyl-2,20-bipyridine), and two cyano-bridged heterobimetallic complexes, [Cu2(bpca)2-
(H2O)2Fe2(5,50-dmbipy)2(CN)8] ꢁ 2[Cu(bpca)Fe(5,50-dmbipy)(CN)4] ꢁ 4H2O (4) and [Cu(bpca)Fe(4,40-dmbipy)(CN)4]n (5) (bpca = bis(2-
pyridylcarbonyl)amidate), have been synthesized and structurally characterized. Complex 4 contains two dinuclear and one tetranuclear
heterobimetallic clusters in an asymmetric unit whereas the structure of complex 5 features a one-dimensional heterobimetallic zigzag
chain. The Cu(II) ion is penta-coordinated in the form of a distorted square-based pyramid. Magnetic studies show ferromagnetic cou-
pling between Cu(II) and Fe(III) ions with g = 2.28, J1 = 2.64 cmꢀ1, J2 = 5.40 cmꢀ1 and TIP = ꢀ2.36 ꢂ 10ꢀ3 for complex 4, and
g = 2.17, J = 4.82 cmꢀ1 and zJ0 = 0.029 cmꢀ1 for complex 5.
Ó 2008 Elsevier B.V. All rights reserved.
Keywords: Tetracyanometalate; Cyano-bridged complexes; Heterobimetallic; Crystal structures; Magnetic properties
1. Introduction
cyano-bridged complexes is from the reaction of hexacyano-
metallates and partially blocked transition metal ions with
organic polydentate ligands [3,4,39–43]. Recently, synthetic
strategies to prepare cyano-bridged heterobimetallic systems
by using modified cyanometalates ([M(L)y(CN)x](xꢀm)ꢀ) as
multidentate ligands were developed. The following are
The cyano-bridged heterobimetallic assemblies are the
continuous interesting topics in the field of molecule-based
magnets during the last decades [1–7]. The variety in their
structures associated with interesting magnetic properties,
such as room temperature magnets [8–11], electrochemically
tunable magnets [12,13], photo- and electro-magnetism [14–
20], spin crossover materials [21–24], single-molecule mag-
nets [25–34] and single-chain magnets [7,35–38], is at the
main origin of the importance in these compounds. One of
the synthetic approaches for low-dimensional heterometallic
some typical examples: [M(L)(CN)4]ꢀ (M = Cr3+, Fe3+
L = 1,10-phenanthroline; or 2,20-bipyridine or 2-amino-
methylpyridine) [44–50], [(tacn)M(CN)3] (M = Co3+, Cr3+
,
;
tacn = 1,4,7-triazacyclononane) and [(Me3tacn)M(CN)3]
(M = Cr3+, Mo3+; Me3tacn = N,N0,N00-trimethyl-1,4,7-tri-
azacyclononane) [51–55], [(tach)M(CN)3] (M = Cr3+
,
Fe3+, Co3+; tach = 1,3,5-triaminocyclohexane) [56], [(Tp)Fe
(CN)3]ꢀ (Tp = hydrotris(pyrazolyl)borate and its deriva-
tives) [30–34,37,57–62], [Fe(bpca)(CN)3]ꢀ (bpca = bis(2-
pyridylcarbonyl)amidate) [63,64] and [Cp*M(CN)3]ꢀ
*
Corresponding authors. Address: Coordination Chemistry Institute,
State Key Laboratory of Coordination Chemistry, Nanjing University,
Nanjing 210093, PR China. Tel.: +86 25 83593893; fax: +86 25 83314502
(J.-L. Zuo).
(M = Co3+
,
Cp = cyclopentadienyl; M = Rh3+
,
Ir3+
,
Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl) [65–68]. On
E-mail address: zuojl@nju.edu.cn (J.-L. Zuo).
0020-1693/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2008.02.036

2902
H.-R. Wen et al. / Inorganica Chimica Acta 361 (2008) 2901–2908
the basis of these building blocks, some heterobimetallic
complexes exhibiting interesting structures and magnetic
properties were synthesized [44–69], including several sin-
gle-molecule magnets (SMMs) [25,29–34] and single-chain
magnets (SCMs) [35–38]. To further investigate the structure
and magnetic properties of low-dimensional heterobimetal-
lic complexes based on the versatile building block of
[M(L)(CN)4]ꢀ, we synthesized two building blocks, [Fe-
(5,50-dmbipy)(CN)4]ꢀ (2), [Fe(4,40-dmbipy)(CN)4]ꢀ (3)
(4,40-dmbipy = 4,40-dimethyl-2,20-bipyridine, 5,50-dmbipy =
5,50-dimethyl-2,20-bipyridine). The structure of 3 has been
reported briefly in a recent review [7]. Based on the above
two new tetracyanometalate building blocks, two novel
cyano-bridged heterobimetallic assemblies were synthesized,
namely, [Cu2(bpca)2(H2O)2Fe2(5,50-dmbipy)2(CN)8] ꢁ 2[Cu
(bpca) Fe(5,50-dmbipy)(CN)4] ꢁ 4H2O (4) and [Cu(bpca)
Fe(4,40-dmbipy)(CN)4]n (5) (bpca = bis(2-pyridylcarbonyl)
amidate). Herein, their structures and magnetic properties
are presented.
2.3. Preparation of (Ph4P)[Fe(5,50-dmbipy)(CN)4] (2)
Chlorine gas was bubbled through a dark red aqueous
solution (100 mL) of K2[Fe(5,50-dmbipy)(CN)4] ꢁ 3H2O
(1.9 g, 4 mmol) for 10 min. under continuous stirring at
room temperature. A color change from red to orange-
red was observed, and the small fraction of insoluble
material was removed by filtration. The addition of a con-
centrated aqueous solution (10 mL) of tetraphenylphos-
phonium chloride (8 mmol, 3.00 g) caused the
precipitation of complex 2 as an orange solid, which was
recrystallized in acetonitrile to afford X-ray-quality orange
crystals, (Ph4P)[Fe(5,50-dmbipy)(CN)4]. Yield: 2.0 g, 70%.
Anal. Calc. for C40H32FeN6P: C, 70.22; H, 4.68; N,
12.29. Found: C, 70.35; H, 4.57; N, 12.17%. IR (KBr,
cmꢀ1): 2123 (mC„N). The tetrabutylammonium salt of 2
was also prepared by the addition of a concentrated aque-
ous solution of tetrabutylammonium chloride.
2.4. Preparation of (Ph4P)[Fe(4,40-dmbipy)(CN)4] ꢁ H2O
(3)
2. Experimental
2.1. Reagents
Complex 3 was prepared as described for 2 except 4,40-
dimethyl-2,20-bipyridine was used instead of 5,50-
dimethyl-2,20-bipyridine. Yield: 71%. Recrystallization of
tetraphenylphosphonium salt of 3 in acetonitrile afforded
X-ray-quality orange crystals, (Ph4P)[Fe(4,40-dmbi-
py)(CN)4] ꢁ H2O. Anal. Calc. for C40H34FeN6OP: C,
68.42; H, 4.85; N, 11.97. Found: C, 68.05; H, 4.77; N,
11.65%. IR (KBr, cmꢀ1): 2122 (mC„N). The tetrabutylam-
monium salt of 3 was also prepared by the addition of a
concentrated aqueous solution of tetrabutylammonium
chloride.
All chemicals were of reagent grade and used as
received. 4,40-dimethyl-2,20-bipyridine, 5,50-dimethyl-2,20-
bipyridine, and 1,3,5-tris(2-pyridyl) triazine were pur-
chased from the Aldrich Chemicals Company. Hbpca
was prepared according to the literature method [70].
Caution! While no problems were encountered in this
work, the perchlorate salts are potentially explosive and cya-
nides are very toxic. Thus, these starting materials should be
handled in small quantities and with great caution.
2.2. Preparation of K2[Fe(5,50-dmbipy)(CN)4] ꢁ 3H2O (1)
2.5. Preparation of [Cu2(bpca)2(H2O)2Fe2(5,50-dmbipy)2-
(CN)8] ꢁ 2[Cu(bpca)Fe(5,50-dmbipy)(CN)4] ꢁ 4H2O (4)
Complex 1 was synthesized by the modification of a lit-
erature method [71]. 2.76 g (0.015 mol) of 5,50-dimethyl-
2,20-bipyridine and 2.0 g (0.05 mol) of ferrous ammonium
sulfate hexahydrate were dissolved in 200 mL of distilled
water. The mixture was heated to slightly below the boiling
point under stirring. KCN (5.0 g) in 10 mL of water was
added all at once to the hot solution. After the solution
was stirred for 1 h, 200 mL of the aqueous solution con-
taining 25 g of KCN was added to the dark red solution.
The mixture was heated for 24 h at 120 °C with continuous
stirring. After cooling and filtration to remove the small
fraction of insoluble material, the filtrate was heated at
110 °C to vaporize the water until the volume of solution
was left approximately 100 mL. After a few hours of cool-
ing and aging, the dark red crystalline product was isolated
by filtration, washed with diethyl ether, and dried under
vacuum at room temperature. Recrystallization in metha-
nol afforded violet-red crystals, K2[Fe(5,50-dmbi-
py)(CN)4] ꢁ 3H2O (1). Yield: 83%. Anal. Calc. for
C16H18N6O3K2Fe: C, 40.33; H, 3.78; N, 17.64. Found: C,
40.60; H, 3.82; N, 17.46%. IR (KBr, cmꢀ1): 2033 (mC„N).
A
solution containing Cu(ClO4)2 ꢁ 6H2O (18.6 mg,
0.05 mmol) and Hbpca (11.4 mg, 0.05 mmol) in water
(2 mL) was added to the glass tube, and a mixture of meth-
anol and water (20 mL, methanol/water (v/v) = 4:1) was
gently added as an upper layer.
A
solution of
(Bu4N)[Fe(5,50-dmbipy)(CN)4] (30 mg, 0.05 mmol) in
methanol (2 mL) was added carefully as a third layer,
and then the tube sealed. Complex 4 was obtained as
blue-black needle-shaped crystals after several weeks. The
resulting crystals were filtered and washed with H2O and
MeOH. Yield: 43%. Anal. Calc. for C112H92Cu4Fe4N36O14:
C, 50.88; H, 3.48; N, 19.07. Found: C, 51.29; H, 3.54; N,
19.39%. IR (KBr, cmꢀ1): 2130, 2157 (mC„N).
2.6. Preparation of [Cu(bpca)Fe(4,40-dmbipy)(CN)4]n (5)
Complex 5 was prepared as described for 4 except
(Bu4N)[Fe(4,40-dmbipy)(CN)4] ꢁ H2O was used instead of
(Bu4N)[Fe(5,50-dmbipy)(CN)4]. Complex 5 was obtained
as blue-black needle-shaped crystals. Yield: 43%. Anal.

H.-R. Wen et al. / Inorganica Chimica Acta 361 (2008) 2901–2908
2903
Calc. for C28H20CuFeN9O2: C, 53.05; H, 3.15; N, 19.88.
Found: C, 53.29; H, 3.24; N, 19.79%. IR (KBr, cmꢀ1):
2129, 2181 (mC„N).
and refined as riding atoms with a uniform value of Uiso. A
summary of the crystal data collection and refinement
parameters for complexes 2–5 is given in Table 1.
2.7. Physical measurements
3. Results and discussion
Elemental analyses for C, H and N were performed
on a Perkin–Elmer 240C analyzer. Infrared spectra were
recorded on a Vector22 Bruker spectrophotometer with
KBr pellets in the 400–4000 cmꢀ1 region. The magnetic
susceptibility measurements of the polycrystalline sam-
ples were measured over the temperature range of 1.8–
300 K with a Quantum Design MPMS-XL7 SQUID
magnetometer using an applied magnetic field from
100 to 2000 Oe. Field dependences of magnetization
were measured using a flux magnetometer in an applied
field up to 70 kOe.
3.1. Syntheses and spectroscopic studies
In an effort to continue the remarkably diverse chemis-
try starting from a tailored cyanometalate precursor, we
explored the synthesis and use of the building blocks with
low-spin iron(III) ions, [Fe(5,50-dmbipy)(CN)4]ꢀ (2) and
[Fe(4,40-dmbipy)(CN)4]ꢀ (3). The complexes, [Fe(bipy)-
(CN)4]ꢀ and [Fe(phen)(CN)4]ꢀ were synthesized early in
the 1960s [71], but the crystal structures were not
determined until 2002 [44,45]. Complexes 2 and 3 were
synthesized by a modified literature method [71]. The yield
is relatively high and the synthetic work-up is simple. The
paramagnetic result of magnetic measurements and the
cyanide stretching frequency at 2123 and 2122 cmꢀ1
demonstrate the low-spin character of the iron(III) in 2
and 3.
Based on the new building blocks, [Fe(4,40-
dmbipy)(CN)4]ꢀ and [Fe(5,50-dmbipy)(CN)4]ꢀ, after the
reactions with the partially blocked copper(II) complex
[Cu(bpca)]+, two novel cyano-bridged heterometallic
assemblies were synthesized. The IR absorptions for bridg-
ing and terminal cyanide ligands occur at 2157 and
2130 cmꢀ1 for complex 4, and at 2129 and 2181 cmꢀ1 for
complex 5, respectively. The products differ very dramati-
cally by using different tetracyanometalate building blocks.
2.8. X-ray crystallography measurements of complexes 2–5
The crystal structures of complexes 2–5 were determined
on a Bruker SMART CCD diffractometer using monochro-
˚
mated Mo Ka radiation (k = 0.71073 A). Absorption cor-
rections were applied using SADABS supplied by Bruker.
Structures were solved by direct methods using the program
SHELXTL-97. The positions of the metal atoms and their first
coordination spheres were located from direct methods E-
maps; other non-hydrogen atoms were found using alternat-
ing difference Fourier syntheses and least-squares refinement
cycles and, during the final cycles, were refined anisotropi-
cally. Hydrogen atoms were placed in calculated position
Table 1
Crystallographic data for complexes 2–5
2
3
4
5
Empirical formula
Formula weight
Crystal system
Space group
C
683.54
40H32FeN6P
C40H34FeN6OP
701.55
orthorhombic
Pbcn
C112H92Cu4Fe4N36O14
2643.78
triclinic
C28H20CuFeN9O2
633.92
monoclinic
P21/n
6.8414 (14)
30.770(6)
13.349(3)
90
103.68(3)
90
2730.5(10)
4
1.542
293(2)
1.354
monoclinic
P21/c
9.2930(9)
24.980(5)
14.904(3)
90
94.29(3)
90
3447.7(12)
4
ꢀ
P1
˚
a (A)
22.805(5)
18.797(4)
16.504(4)
90
90
90
7074(4)
8
1.317
293(2)
8.934 (2)
14.745(4)
24.065(6)
74.612(2)
81.973(4)
75.591(4)
2951.0(12)
1
1.488
293(2)
1.260
1348
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
V (A )
Z
q (calc) (g cmꢀ3
T (K)
)
1.317
293(2)
0.522
1420
l (mmꢀ1
F(000)
)
0.512
2900
1288
Index ranges
0 6 h 6 11,
0 6 k 6 29,
ꢀ17 6 l 6 17
6702/0/435
1.020
0.0489, 0.1219
0.1578, 0.1561
0.367 and ꢀ0.293
ꢀ21 6 h 6 30,
ꢀ24 6 k 6 24,
ꢀ20 6 l 6 21
8484/0/444
0.908
0.0550, 0.1139
0.1085, 0.1289
0.585 and ꢀ0.363
ꢀ10 6 h 6 11,
ꢀ17 6 k 6 18,
ꢀ18 6 l 6 29
11282/0/797
1.086
0.0631, 0.1238
0.0933, 0.1290
0.542 and ꢀ0.601
ꢀ8 6 h 6 8,
ꢀ37 6 k 6 37,
ꢀ14 6 l 6 16
5375/0/372
0.977
0.0562, 0.0935
0.1030, 0.1004
0.486 and ꢀ0.569
Data/restraints/parameters
Goodness-of-fit (F2)
b
R1a, wR2 (I > 2r(I))
b
R1a, wR2 (all data)
ꢀ3
˚
Largest differences in peak and hole (e A
)

2904
H.-R. Wen et al. / Inorganica Chimica Acta 361 (2008) 2901–2908
Table 2
If using the parent unsubstituted bipyridine compound
[Fe(bpy)(CN)4]ꢀ, the final product is the neutral heterodi-
nuclear species, {[Fe(bipy)(CN)4][Cu(bpca)(H2O)]} [7].
˚
Selected bond lengths (A) and angles (°) for complexes 2 and 3
2
3
Bond distances
Fe(1)–C(13)
Fe(1)–C(14)
Fe(1)–C(15)
Fe(1)–C(16)
Fe(1)–N(1)
Fe(1)–N(2)
1.931(5)
1.922(5)
1.966(5)
1.972(5)
2.004(3)
1.910(3)
Fe(1)–C(1)
Fe(1)–C(2)
Fe(1)–C(3)
Fe(1)–C(4)
Fe(1)–N(1)
Fe(1)–N(2)
1.910(3)
1.918(3)
1.949(3)
1.949(3)
1.986(2)
1.980(2)
3.2. Crystal structures
The structures of complexes 2 and 3 feature mononu-
clear [Fe(5,50-dmbipy)(CN)4]ꢀ or [Fe(4,40-dmbipy)(CN)4]ꢀ
anions, respectively (Fig. 1). The iron(III) ions in both
complexes are coordinated by two nitrogen atoms from
2,2-bipyridine derivatives and four cyanide carbon atoms,
taking a distorted octahedral geometry. The small bond
angle (N(1)–Fe(1)–N(2), 80.66(15)° for 2, 80.61(19)° for
3) around Fe(1) with chelating bipy is one of the main fac-
tors accounting for this distortion. The Fe(1)–N(bipy)
Bond angles
N(1)–Fe(1)–N(2)
N(1)–Fe(1)–C(13)
N(2)–Fe(1)–C(14)
C(13)–Fe(1)–C(15)
N(1)–Fe(1)–C(15)
N(2)–Fe(1)–C(16)
80.66(15)
96.59(16)
95.93(17)
90.76(19)
90.75(1)
89.56(1)
N(1)–Fe(1)–N(2)
N(1)–Fe(1)–C(1)
N(2)–Fe(1)–C(2)
C(1)–Fe(1)–C(2)
N(1)–Fe(1)–C(3)
N(2)–Fe(1)–C(4)
80.61(9)
98.50(10)
94.90(10)
86.28(11)
88.40(10)
86.29(9)
˚
bond distances in 2 and 3 (1.980–2.004 A) are almost the
same as those found in the low-spin iron(III) compound
of [FeIII(bipy)(CN)4]ꢀ (1.987–2.003 A). Good agreement
˚
apical position is occupied by one nitrogen atom from a
cyanide group of another [Fe(5,50-dmbipy)(CN)4]ꢀ
(Cu(1)–N(5), 2.313 A). The Fe ion has a distorted octa-
is observed between the Fe(1)–C(cyano) bond distances
˚
III
˚
of 2 and 3 (1.900–1.972 A) and those reported for cyano-
containing mononuclear low-spin iron(III) complexes.
The bipy ligand is almost planar. The bond angles of Fe–
C„N range from 177.0 to 178.3°. The selected bond
lengths and angles for complexes 2–5 are given in Tables
2 and 3.
hedral geometry, completed by two nitrogen atoms from
a 5,50-dmbipy ligand and four carbon atoms from the cya-
nide groups. The square is slightly distorted, as reflected in
the bond angles of C(15)–Fe(1)–C(16) [86.41(16)°] and
N(5)–Cu(1)–N(9)#1 (91.25(13)°; #1: ꢀx + 1, ꢀy, ꢀz + 1).
The plane made up of the bpca ligand and Cu(II) (N(8),
C(23), N(7), C(22), N(6), Cu(1)) is almost perpendicular
to the plane made up of 5,50-dmbipy ligand and Fe(III)
(N(1), C(6), C(7), N(2), Fe(1)).
The crystal structure measurements show that 4 is a co-
crystallized compound with two dinuclear and one tetranu-
clear heterobimetallic clusters in an asymmetric unit
(Fig. 2). The dinuclear cluster is a neutral cyano-bridged
dimer. The [(bpca)Cu(H2O)]+ unit is linked to the
[Fe(5,50-dmbipy)(CN)4]ꢀ unit by one cyanide group with
Different from complex 4, the structure of complex 5
consists of Fe(4,40-dmbipy)(CN)4Cu(bpca) unit which
forms a neutral one-dimensional zigzag chain (Fig. 3).
Within the chain, the CuII ion is penta-coordinated in the
form of a distorted square-based pyramid. Three nitrogen
atoms from the bpca ligand and a nitrogen atom from a
cyanide group of [Fe(4,40-dmbipy)(CN)4]ꢀ form the equa-
˚
Cu(2)–N(15) bond distance of 1.945(3) A. The tetranuclear
cluster is a neutral cyano-bridged compound of square.
Within the square, each [(bpca)Cu]+ unit is linked to two
[Fe(5,50-dmbipy)(CN)4]ꢀ units by two cyanide groups
atcis-position. The CuII ion is penta-coordinated in the
form of a distorted square-based pyramid. Three nitrogen
atoms from a bpca ligand and a nitrogen atom from a cya-
nide group of [Fe(5,50-dmbipy)(CN)4]ꢀ form the equatorial
˚
torial plane with bond distances of 2.097–2.234 A (Cu–
N), and the apical position is occupied by one nitrogen
atom from
a
cyanide group of another [Fe(4,40-
˚
˚
dmbipy)(CN)4]ꢀ unit with a bond length of 2.036 A
plane with bond distances of 1.947(3)–2.026(3) A, and the
[Fe(5, 5’-dmbipy)(CN)4]−
[Fe(4, 4’-dmbipy)(CN)4]−
Fig. 1. ORTEP representation of the anion building blocks in complexes 2 and 3. The thermal ellipsoids are drawn at 30% probability.

H.-R. Wen et al. / Inorganica Chimica Acta 361 (2008) 2901–2908
2905
Fig. 2. ORTEP representation of the selected unit of complex 4. The thermal ellipsoids are drawn at 30% probability. Symmetry code for the generated
atoms: (a) 1 ꢀ x, ꢀy, 1 ꢀ z.
Table 3
a
˚
Selected bond lengths (A) and angles (°) for complexes 4 and 5
4
5
Bond distances
Cu(1)–N(5)
Cu(1)–N(6)
Cu(1)–N(7)
Cu(1)–N(8)
Cu(1)–N(9)#1
Cu(2)–N(15)
Cu(2)–O(5)
Fe(1)–C(16)
Fe(1)–C(15)
C(16)–N(5)
C(13)–N(3)
2.313(3)
1.999(4)
1.947(3)
2.026(3)
1.953(3)
1.945(3)
2.311(2)
1.911(4)
1.900(4)
1.147(4)
1.140(3)
Cu(1)–N(1)
Cu(1)–N(9)
Cu(1)–N(7)
Cu(1)–N(8)
Cu(1)–N(2)#2
Fe(1)–C(1)
Fe(1)–C(3)
C(1)–N(1)
2.097(3)
2.100(3)
2.205(3)
2.234(3)
2.036(3)
1.911(4)
1.900(4)
1.172(4)
1.179(4)
C(3)–N(3)
Bond angles
N(5)–Cu(1)–N(6)
N(5)–Cu(1)–N(7)
N(5)–Cu(1)–N(8)
N(5)–Cu(1)–N(9)#1
C(15)–Fe(1)–C(16)
C(15)–Fe(1)–N(1)
C(16)–Fe(1)–N(2)
Fe(1)–C(16)–N(5)
Fe(1)–C(14)–N(4)
Cu(2)–N(4)–C(41)
a
96.13(13)
93.12(13)
97.59(13)
91.25(13)
86.41(16)
178.62(12)
176.32(11)
178.4(3)
N(2)#2-Cu(1)–N(1)
N(2)#2-Cu(1)–N(9)
N(2)#2-Cu(1)–N(7)
N(2)#2-Cu(1)–N(8)
C(1)–Fe(1)–C(3)
C(2)–Fe(1)–C(3)
C(3)–Fe(1)–N(5)
C(3)–Fe(1)–N(6)
Fe(1)–C(1)–N(1)
95.80(13)
132.26(12)
93.33(11)
103.19(12)
97.74(16)
83.44(15)
87.17(14)
93.10(14)
178.5(3)
176.7(3)
177.2(4)
Symmetry transformation used to generate equivalent atoms: #1
ꢀx + 1, ꢀy, ꢀz + 1; #2 x + 1, y, z.
(Cu(1)–N(2)#2; #2: x + 1, y, z). The plane made up of the
bpca ligand and Cu(II) (N(8), C(23), N(9), C(22),
N(7),Cu(1)) is almost perpendicular to the plane made up
of 4,40-dmbipy ligand and Fe(III) (N(5), C(5), C(10),
N(6), Fe(1)). The pyridine ring of the bpca ligands from
adjacent chains in the crystal exhibits a quasi-parallel
(dihedral angle 3.0°) stacking along the a-axis, and the
shorter interchain pyridine–pyridine interplanar separation
Fig. 3. Top: ORTEP representation of the selected unit of complex 5. The
thermal ellipsoids are drawn at 30% probability. Symmetry code for the
generated atoms: (a) 1 + x, y, z. Bottom: view of the 1D chain structure of
5 along the a-axis. The hydrogen atoms are omitted for clarity.
3.3. Magnetic properties
Magnetic measurements for complexes 4 and 5 were per-
formed on polycrystalline samples in the temperature range
of 1.8–300 K. The temperature dependence of susceptibility
˚
(ca. 3.580 A) indicates that there are weak interchain p–p
stacking interactions.

2906
H.-R. Wen et al. / Inorganica Chimica Acta 361 (2008) 2901–2908
for 4 in the forms of vM and vMT versus T at 2 kOe is
shown in Fig. 4. The value of vMT at room temperature
is 3.30 emu K molꢀ1, which is slightly higher than the
spin-only value of 3.20 emu K molꢀ1 based on the Fe4Cu4
unit (gFe = gCu = 2.1, SFe = SCu = 1/2). As the tempera-
ture decreases, vMT gradually increases and reaches
4.50 emu K molꢀ1 at 25 K, and then it abruptly increases
reaching 5.40 emu K molꢀ1 at 1.8 K, indicating the ferro-
magnetic coupling between the CuII and FeIII ions, which
is further confirmed by the nearly saturated magnetization
value of 8.46Nb molꢀ1 under the 70 kOe magnetic field at
1.8 K (Fig. 5). According to the structure, the Hamiltonian
tively. Thus, the Van Vleck expression can be written as
follows when TIP is taken into account:
ꢂ
2Ng2b2
kT
2 þ eꢀ2J
þ 5e2J
1=kT
1=kT
vM
¼
7 þ eꢀ4J
þ 3eꢀ2J =kT þ 5e2J =kT
1=kT
1
1
ꢃ
2
þ
þ TIP
ð1Þ
3 þ eꢀ2J =kT
2
The best fit between 12 and 300 K gives the para-
meters: g = 2.28, J1 = 2.64 cmꢀ1, J2 = 5.40 cmꢀ1 and TIP =
.
ꢄ
ꢅ
P
2
ꢀ2.36 ꢂ 10ꢀ3 with R ¼
ðvMT Þcalcd ꢀ ðvMTÞobsd
P
2
ðvMT Þobsd ¼ 9:2 ꢂ 10ꢀ4. This result indicates that the cya-
nide ligand mediates the ferromagnetic coupling between
the CuII and FeIII ions.
h
ꢀ
ꢁ
b
b
b
b
of 4 can be described as H ¼ ꢀ2J1 SFe1 SCu1 þ SCu1A
þ
ꢀ
ꢁ
The temperature dependence of susceptibility at 2 kOe
for 5 is shown in Fig. 6. The vMT value at room tempera-
ture is 0.93 emu K molꢀ1, and it goes up in a mild way in
the temperature range of 10–300 K, followed by a sharp
increase with 3.35 emu K molꢀ1 at 1.8 K, suggesting the
ferromagnetic coupling between the FeIII and CuII ions.
The field dependence of magnetization was measured at
1.8 K (Fig. 7). The magnetization gradually increases with
the applied field and reaches a value of 1.79Nb molꢀ1 at
70 kOe, which is lower than the theoretical value of
2.10Nb molꢀ1 based on the CuFe unit (2.1 ꢂ 1/2 +
2.1 ꢂ 1/2) with ferromagnetic coupling between the FeIII
and CuII ions, indicating that the magnetization does not
reach saturation at this field. According to the structure,
complex 5 can be regarded as a one-dimensional uniform
b
b
b
b
b
SFe1A SCu1 þ SCu1A ꢃ ꢀ 2 ꢂ 2J2SFe2
S
Cu2, where J1 and J2
are the coupling constants mediated by cyanide in tetranu-
clear Fe2Cu2 cluster and dinuclear FeCu cluster, respec-
6
3
2
5
1
χ
0
T
4
ꢀ
ꢁ
0
50
100
150
200
250
300
χ
P
nꢀ1
i¼1
b
b
b
T
/ K
chain H ¼ ꢀJ
SA ꢁ SA
[72]. When the intermolec-
i
iþ1
ular interaction (zj0) is taken into account, the van Vleck
formula is written as
ꢆ ꢇ
2=3
Ng2b2
4kT
N
D
3
0
50
100
150
/ K
200
250
300
vchain
vM
¼
ð2Þ
ð3Þ
T
vchain
Fig. 4. Temperature dependence of vMT for complex 4 at 2000 Oe. The
solid line represents the best-fit to the data. Inset: temperature dependence
of vM for complex 4.
¼
1 ꢀ ð2zj0=Ng2b2Þvchain
4
2
8
3
1
6
χ
β
2
N
T
0
4
χ
M
0
50
100
200
250
300
T
15/0 K
2
1
0
0
50
100
150
/ K
200
250
300
-10
0
10
20
30
40
50
60
70
80
T
H
/ kOe
Fig. 6. Temperature dependence of vMT for complex 5 at 2000 Oe. The
solid line represents the best-fit to the data. Inset: temperature dependence
of vM for complex 5.
Fig. 5. Field dependence of the magnetization for complex 4 at 1.8 K. The
solid line is a guide for the eyes.

H.-R. Wen et al. / Inorganica Chimica Acta 361 (2008) 2901–2908
2907
Acknowledgements
2.0
1.5
1.0
0.5
0.0
This work was supported by the National Natural Sci-
ence Foundation of China (Nos. 50662001 and
20725104), Natural Science Foundation of Jiangxi Prov-
ince (No. 0520007), and the Development Program of Sci-
ence and Technology of the Education Department of
Jiangxi Province (Nos. 2005-221 and 2006-327).
β
N
M
References
[1] K.R. Dunbar, R.A. Heintz, Prog. Inorg. Chem. 45 (1997) 283.
[2] M. Verdaguer, A. Bleuzen, V. Marvaud, J. Vaissermann, M.
Seuleiman, C. Desplanches, A. Scuiller, C. Train, R. Garde, G.
Gelly, C. Lomenech, I. Rosenman, P. Veillet, C. Cartier, F. Villain,
Coord. Chem. Rev. 190–192 (1999) 1023.
0
10
20
30
40
50
60
H
/ kOe
¯
[3] M. Ohba, H. Okawa, Coord. Chem. Rev. 198 (2000) 313.
ˇ
´
´ˇ
ˇ ˇ ´
ˇ
´ˇ
´
[4] J. Cernak, M. Orendac, I. Potocnak, J. Chomic, A. Orendacova, J.
Skorsˇepa, A. Feher, Coord. Chem. Rev. 224 (2002) 51.
[5] J.S. Miller, MRS Bull. 25 (2000) 60.
Fig. 7. Field dependence of the magnetization for complex 5 at 1.8 K. The
solid line is a guide for the eyes.
[6] V. Marvaud, C. Decroix, A. Scuiller, C. Guyard-Duhayon, J.
Vaissermann, F. Gonnet, M. Verdaguer, Chem. Eur. J. 9 (2003) 1677.
[7] R. Lescoue¨zec, L.M. Toma, J. Vaissermann, M. Verdaguer, F.S.
Delgado, C. Ruiz-Pe´rez, F. Lloret, M. Julve, Coord. Chem. Rev. 249
(2005) 2691.
where
N ¼ 1:0 þ 5:79799y þ 16:902653y2 þ 29:376885y3
þ 29:832959y4 þ 14:036918y5
D ¼ 1:0 þ 2:7979916y þ 7:0086780y2 þ 8:6538644y3
þ 4:5743114y4
`
[8] S. Ferlay, T. Mallah, R. Quahes, P. Veillet, M. Verdaguer, Nature 378
(1995) 701.
[9] S.M. Holmes, G.S. Girolami, J. Am. Chem. Soc. 121 (1999) 5593.
[10] Ø. Hatlevik, W.E. Buschman, J. Zhang, J.L. Manson, J.S. Miller,
Adv. Mater. 11 (1999) 914.
[11] R. Garde, F. Villain, M. Verdaguer, J. Am. Chem. Soc. 124 (2002)
10531.
[12] O. Sato, T. Iyoda, A. Fujishima, K. Hashimoto, Science 271 (1996)
49.
[13] O. Sato, S. Hayami, Y. Einaga, Z.Z. Gu, Bull. Chem. Soc. Jpn. 76
(2003) 443.
[14] O. Sato, T. Iyoda, A. Fujishima, K. Hashimoto, Science 272 (1996)
704.
[15] S.I. Ohkoshi, A. Fujishima, K. Hashimoto, J. Am. Chem. Soc. 120
(1998) 5349.
[16] O. Sato, Y. Einaga, A. Fujishima, K. Hashimoto, Inorg. Chem. 38
(1999) 4405.
[17] N. Shimamoto, S.I. Ohkoshi, O. Sato, K. Hashimoto, Inorg. Chem.
41 (2002) 678.
y ¼ J=2kT
The best fit by least squares gives the paꢀra1meters:
g = 2.17, J = 4.82 cmꢀ1 and zJ0 = 0.029 cm
with
R = 4.0 ꢂ 10ꢀ4, indicating the existence of ferromagnetic
interaction. The AC susceptibility studies carried out in
a 5 Oe oscillating field with frequencies up to 1500 Hz
for 5 showed no evidence for slow paramagnetic relax-
ation, suggesting that complex 5 is not a single-chain
magnet.
In summary, two new tetracyanide-containing building
blocks 2 and 3 were synthesized and characterized. The
incorporations of 2 and 3 with partially blocked salt
[Cu(bpca)]2+ afford compound (4) consisting of dimeric
FeCu and tetrameric Fe2Cu2, and a zigzag chain (5). Mag-
netic properties studies show ferromagnetic coupling
between Cu(II) and Fe(III) ions with g = 2.28,
J1 = 2.64 cmꢀ1 and J2 = 5.40 cmꢀ1 for 4, and g = 2.17,
J = 4.82 cmꢀ1 and zJ0 = 0.029 cmꢀ1 for 5. The present
results suggest that the mononuclear compounds 2 and 3
are the possible building blocks for assembling new cya-
nide-bridged heterometallic high-spin clusters and low-
dimensional polymers with interesting magnetic properties.
[18] T. Yokoyama, K. Okamoto, T. Ohta, S.I. Ohkoshi, K. Hashimoto,
Phys. Rev. B 65 (2002) 064438.
[19] Y. Arimoto, S.I. Ohkoshi, Z.J. Zhong, H. Seino, Y. Mizobe, K.
Hashimoto, J. Am. Chem. Soc. 125 (2003) 9240.
[20] O. Sato, Acc. Chem. Res. 36 (2003) 692.
[21] V. Niel, A.L. Thompson, M.C. Munoz, A. Galet, A.E. Goeta, J.A.
˜
Real, Angew. Chem., Int. Ed. 42 (2003) 3760.
´
[22] G. Molnar, V. Niel, A.B. Gaspar, J.A. Real, A. Zwick, A.
Bousseksou, J.J. McGarvey, J. Phys. Chem. B 106 (2002) 9701.
´
[23] G. Molnar, V. Niel, J.A. Real, L. Dubrovinsky, A. Bousseksou, J.J.
McGarvey, J. Phys. Chem. B 107 (2003) 3149.
[24] M. Nihei, M. Ui, M. Yokota, L. Han, A. Maeda, H. Kishida, H.
Okamoto, H. Oshio, Angew. Chem., Int. Ed. 44 (2005) 6484.
[25] J.J. Sokol, A.G. Hee, J.R. Long, J. Am. Chem. Soc. 124 (2002)
7656.
4. Supplementary material
´
[26] C.P. Berlinguette, D. Vaughn, C. Canada-Vilalta, J.R. Galan-
˜
Mascaro´s, K.R. Dunbar, Angew. Chem., Int. Ed. 42 (2003) 1523.
[27] V.S. Mironov, L.F. Chibotaru, A. Ceulemans, J. Am. Chem. Soc. 125
(2003) 9750.
[28] H.J. Choi, J.J. Sokol, J.R. Long, Inorg. Chem. 43 (2004) 1606.
[29] E.J. Schelter, A.V. Prosvirin, K.R. Dunbar, J. Am. Chem. Soc. 126
(2004) 15004.
CCDC 663215, 663216, 663217, and 663218 contain the
supplementary crystallographic data for this paper. These
data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.

2908
H.-R. Wen et al. / Inorganica Chimica Acta 361 (2008) 2901–2908
[30] S. Wang, J.L. Zuo, H.C. Zhou, H.J. Choi, Y. Ke, J.R. Long, X.Z.
You, Angew. Chem., Int. Ed. 43 (2004) 5940.
[31] C.F. Wang, J.L. Zuo, B.M. Bartlett, Y. Song, J.R. Long, X.Z. You, J.
Am. Chem. Soc. 128 (2006) 7162.
[32] W. Liu, C.F. Wang, Y.Z. Li, J.L. Zuo, X.Z. You, Inorg. Chem. 45
(2006) 10058.
[49] L. Toma, L.M. Toma, R. Lescoue¨zec, D. Armentano, G.D. Munno,
M. Andruh, J. Cano, F. Lloret, M. Julve, J. Chem. Soc., Dalton
Trans. (2005) 1357.
[50] L. Toma, R. Lescoue¨zec, J. Vaissermann, P. Herson, V. Marvaud, F.
Lloret, M. Julve, New J. Chem. 29 (2005) 210.
[51] J.L. Heinrich, P.A. Berseth, J.R. Long, Chem. Commun. (1998) 1231.
[52] P.A. Berseth, J.J. Sokol, M.P. Shores, J.L. Heinrich, J.R. Long, J.
Am. Chem. Soc. 122 (2000) 9655.
[53] M.P. Shores, J.J. Sokol, J.R. Long, J. Am. Chem. Soc. 124 (2002) 2279.
[54] J.Y. Yang, M.P. Shores, J.J. Sokol, J.R. Long, Inorg. Chem. 42 (2003) 1403.
´
[33] D. Li, S. Parkin, G. Wang, G.T. Yee, R. Clerac, W. Wernsdorfer,
S.M. Holmes, J. Am. Chem. Soc. 128 (2006) 4214.
[34] Z.G. Gu, W. Liu, Q.F. Yang, X.H. Zhou, J.L. Zuo, X.Z. You, Inorg.
Chem. 46 (2007) 3236.
´
`
[35] R. Lescoue¨zec, J. Vaissermann, C. Ruiz-Perez, F. Lloret, R. Carrasco,
[55] J.N. Rebilly, L. Catala, E. Riviere, R. Guillot, W. Wernsdorfer, T.
M. Julve, M. Verdaguer, Y. Dromzee, D. Gatteschi, W. Wernsdorfer,
Angew. Chem., Int. Ed. 42 (2003) 1483.
[36] L.M. Toma, R. Lescoue¨zec, F. Lloret, M. Julve, J. Vaissermann, M.
Verdaguer, Chem. Commun. (2003) 1850.
Mallah, Inorg. Chem. 44 (2005) 8194.
[56] J.J. Sokol, M.P. Shores, J.R. Long, Angew. Chem., Int. Ed. 40 (2001) 236.
[57] R. Lescoue¨zec, J. Vaissermann, F. Lloret, M. Julve, M. Verdaguer,
Inorg. Chem. 41 (2002) 5943.
[37] S. Wang, J.-L. Zuo, S. Gao, Y. Song, H.-C. Zhou, Y.-Z. Zhang, J.
Am. Chem. Soc. 126 (2004) 8900.
[58] S. Wang, J.L. Zuo, H.C. Zhou, Y. Song, S. Gao, X.Z. You, Eur. J.
Inorg. Chem. (2004) 3681.
´
´
[38] L.M. Toma, R. Lescoue¨zec, J. Pasan, C. Ruiz-Perez, J. Vaissermann,
J. Cano, R. Carrasco, W. Wernsdorfer, F. Lloret, M. Julve, J. Am.
Chem. Soc. 128 (2006) 4842.
[59] D. Li, S. Parkin, G. Wang, G.T. Yee, A.V. Prosvirin, S.M. Holmes,
Inorg. Chem. 45 (2006) 1951.
[60] D. Li, S. Parkin, G. Wang, G.T. Yee, S.M. Holmes, Inorg. Chem. 45
(2006) 2773.
´
[39] E. Colacio, J.M. Domınguez-Vera, M. Ghazi, R. Kiveka¨s, M. Klinga,
´
J.M. Moreno, Chem. Commun. (1998) 1071.
[40] H. Miyasaka, H. Ieda, N. Matsumoto, N. Re, R. Crescenzi, C.
Floriani, Inorg. Chem. 37 (1998) 255.
[61] D. Li, S. Parkin, R. Clerac, S.M. Holmes, Inorg. Chem. 45 (2006) 7569.
[62] H.R. Wen, C.F. Wang, Y. Song, S. Gao, J.L. Zuo, X.Z. You, Inorg.
Chem. 45 (2006) 8942.
[41] R.J. Parker, L. Spiccia, K.J. Berry, G.D. Fallon, B. Moubaraki, K.S.
Murray, Chem. Commun. (2001) 333.
[63] R. Lescoue¨zec, J. Vaissermann, L.M. Toma, R. Carrasco, F. Lloret,
M. Julve, Inorg. Chem. 43 (2004) 2234.
[42] M.S. EI Fallah, J. Ribas, X. Solans, M. Font-Bardia, J. Chem. Soc.,
Dalton Trans. (2001) 247.
[64] H.R. Wen, C.F. Wang, J.L. Zuo, Y. Song, X.R. Zeng, X.Z. You,
Inorg. Chem. 45 (2006) 582.
`
[43] V. Marvaud, C. Decroix, A. Scuiller, F. Tuyeras, C. Guyard-
[65] K.K. Klausmeyer, T.B. Rauchfuss, S.R. Wilson, Angew. Chem., Int.
Ed. 37 (1998) 1694.
[66] K.K. Klausmeyer, S.R. Wilson, T.B. Rauchfuss, J. Am. Chem. Soc.
121 (1999) 2705.
[67] S.M. Contakes, K.K. Klausmeyer, T.B. Rauchfuss, Inorg. Chem. 39
(2000) 2069.
[68] D.J. Darensbourg, W.Z. Lee, M.J. Adams, J.C. Yarbrough, Eur. J.
Inorg. Chem. (2001) 2811.
Duhayon, J. Vaissermann, J. Marrot, F. Gonnet, M. Verdaguer,
Chem. Eur. J. 9 (2003) 1692.
[44] R. Lescoue¨zec, F. Lloret, M. Julve, J. Vaissermann, M. Verdaguer, R.
Llusar, S. Uriel, Inorg. Chem. 40 (2001) 2065.
[45] R. Lescoue¨zec, F. Lloret, M. Julve, J. Vaissermann, M. Verdaguer,
Inorg. Chem. 41 (2002) 818.
[46] L. Toma, R. Lescoue¨zec, J. Vaissermann, F.S. Delgado, C. Ruiz-
´
perez, R. Carrasco, J. Cano, F. Lloret, M. Julve, Chem. Eur. J. 10
[69] L.M.C. Beltran, J.R. Long, Acc. Chem. Res. 38 (2005) 325.
[70] A. Kamiyama, T. Noguchi, T. Kajiwara, T. Ito, Inorg. Chem. 41
(2002) 507.
(2004) 6130.
´
[47] L.M. Toma, F.S. Delgado, C. Ruiz-Perez, R. Carrasco, J. Cano, F.
Lloret, M. Julve, J. Chem. Soc., Dalton Trans. (2004) 2836.
[48] Y.Z. Zhang, S. Gao, Z.M. Wang, G. Su, H.L. Sun, F. Pan, Inorg.
Chem. 44 (2005) 4534.
[71] A.A. Schilt, J. Am. Chem. Soc. 82 (1960) 3000.
[72] G. Baker Jr., G.S. Rushbrooke, H.E. Gilbert, Phys. Rev. 135 (1964)
A1272.