Cyanide-bridged feiii-mniii bimetallic complexes with dimeric and chain structures constructed from a newly made mer-fe tricyanide: structures and magnetic properties

Article abstract of DOI:10.1021/ic802033q

Four cyanide-linked Fe^III-Mn^III complexes were prepared by reacting Mn Schiff bases with a new molecular precursor (PPh ₄)[Fe(qcq)(CN)₃] [1; qcq ) 8-(2-quinolinecarboxamido) quinoline anion]. They include a dime

Full text of DOI:10.1021/ic802033q

Inorg. Chem. 2009, 48, 2956-2966
Cyanide-Bridged FeIII-MnIII Bimetallic Complexes with Dimeric and
Chain Structures Constructed from a Newly Made mer-Fe Tricyanide:
Structures and Magnetic Properties
Jae Il Kim,† Hyun Young Kwak,† Jung Hee Yoon,† Dae Won Ryu,† In Young Yoo,† Namgeun Yang,‡
Beong Ki Cho,§ Je-Geun Park,‡ Hyosug Lee,| and Chang Seop Hong*,†
Department of Chemistry, Korea UniVersity, Seoul 136-713, Korea, Department of Physics and
Department of Energy Science, SungKyunKwan UniVersity, Suwon 440-746, Korea, Department of
Materials Science and Engineering, GIST, Gwangju 500-712, Korea, and Hybrid Materials Group,
Materials Research Laboratory, SAIT, Yongin-City 446-712, Korea
Received October 23, 2008
Four cyanide-linked FeIII-MnIII complexes were prepared by reacting Mn Schiff bases with a new molecular precursor
(PPh4)[Fe(qcq)(CN)3] [1; qcq ) 8-(2-quinolinecarboxamido)quinoline anion]. They include a dimeric molecule,
[Fe(qcq)(CN)3][Mn(3-MeOsalen)(H2O)]·2H2O [2·2H2O; 3-MeOsalen ) N,N′-ethylenebis(3-methoxysalicylideneiminato)
dianion], and three 1D zigzag chains, [Fe(qcq)(CN)3][Mn(5-Clsalen)] · 3H2O [3· 2MeOH; 5-Clsalen ) N,N′-
ethylenebis(5-chlorosalicylideneiminato) dianion], [Fe(qcq)(CN)3][Mn(5-Brsalen)] · 2MeOH [4· 2MeOH; 5-Brsalen )
N,N′-ethylenebis(5-bromosalicylideneiminato) dianion], and Fe(qcq)(CN)3][Mn(salen)] · MeCN · H2O [5· MeCN; salen
) N,N′-ethylenebis(salicylideneiminato) dianion]. The complexes consist of extensive hydrogen bonding and π-π
stacking interactions, generating multidimensional structures. Magnetic studies demonstrate that antiferromagnetic
couplings are operative between FeIII and MnIII centers bridged by cyanide ligands. On the basis of an infinite chain
model, magnetic coupling parameters of 2-5 range from -9.3 to -14.1 cm-1. A long-range order is observed at
2.3 K for 3 and 2.2 K for 4, while compound 5 shows spin glass behavior possibly coupled with magnetic ordering.
Introduction
Recently, low-dimensional magnetic systems with an
anisotropic nature have been one of the hot issues among
molecule-based magnetic materials. Single-molecule magnets
(SMMs) exhibit peculiar slow magnetic relaxation and
quantum tunneling of magnetization below a blocking
temperature.7 Another attractive challenge has been in
regards to the design and fabrication of single-chain magnets
(SCMs), which display the same relaxation effects on
magnetization.8 The construction of such low-dimensional
systems can be more reliably achieved by taking advantage
The research on molecule-based magnetic materials has
attracted much attention because of the materials’ potential
applications in magnetic devices.1 In particular, cyanide-
bridged magnetic complexes have been intensively studied
in view of intriguing multifunctional magnetic characters.2-4
A variety of molecular units, hexacyanometalates or octa-
cyanometalates, have been utilized as synthons to build
discrete molecules or coordination networks.2-6 In this case,
the structural dimensionality can be controlled depending on
experimental conditions and counterparts used.
(3) (a) Dei, A. Angew. Chem., Int. Ed. 2005, 44, 1160. (b) Arimoto, Y.;
Ohkoshi, S.-i.; Zhong, Z. J.; Seino, H.; Mizobe, Y.; Hashimoto, K.
J. Am. Chem. Soc. 2003, 125, 9240. (c) Herrera, J. M.; Marvaud, V.;
Verdaguer, M.; Marrot, J.; Kalisz, M.; Mathonie`re, C. Angew. Chem.,
Int. Ed. 2004, 43, 5468. (d) Ohkoshi, S.-i.; Tokoro, H.; Hozumi,
T. Z. Y.; Hashimoto, K.; Mathonie`re, C.; Bord, I.; Rombaut, G.;
Verlelst, M.; Moulin, C. C. d.; Villain, F. J. Am. Chem. Soc. 2006,
128, 270. (e) Ohkoshi, S.-i.; Ikeda, S.; Hozumi, T.; Kashiwagi, T.;
Hashimoto, K. J. Am. Chem. Soc. 2006, 128, 5320.
(4) (a) Inoue, K.; Kikuchi, K.; Ohba, M.; Okawa, H. Angew. Chem., Int.
Ed. 2003, 42, 4810. (b) Kaneko, W.; Kitagawa, S.; Ohba, M. J. Am.
Chem. Soc. 2007, 129, 248. (c) Imai, H.; Inoue, K.; Kikuchi, K.;
Yoshida, Y.; Ito, M.; Sunahara, T.; Onaka, S. Angew. Chem., Int. Ed.
2004, 43, 5618.
* To whom correspondence should be addressed. E-mail: cshong@
korea.ac.kr.
†
Korea University.
SungKyunKwan University.
GIST.
SAIT.
‡
§
|
(1) Turnbull, M. M.; Sugimoto, T.; Thompson, L. K. Molecule-Based
Magnetic Materials; American Chemical Society: Washington, DC,
1996.
(2) Coronado, E.; Palacio, F.; Veciana, J. Angew. Chem., Int. Ed. 2003,
42, 2570.
2956 Inorganic Chemistry, Vol. 48, No. 7, 2009
10.1021/ic802033q CCC: $40.75  2009 American Chemical Society
Published on Web 02/27/2009

Cyanide-Bridged FeIII-MnIII Bimetallic Complexes
of capped molecular precursors [Fe(L)(CN)x]y- (L ) block-
ing ligands, x ) 2-5) with magnetic anisotropy rather than
using the nonblocked cyanide precursors. The molecule-level
magnets, however, require magnetic anisotropic spin centers
incorporated into molecular units at least, as well as
negligible intermolecular interaction between molecules or
chains with respect to intramolecular interaction. When the
intermolecular interaction becomes significant, the intrinsic
magnetic characters of SMMs and SCMs smear out. For
instance, the presence of sizable intermolecular contacts
(hydrogen bonding, π-π interactions, and so on) allowed
for magnetic systems with field-induced metamagnetic
transition or long-range magnetic ordering.9 Some low-
dimensional assemblies (clusters and chains) showed three-
dimensional (3D) magnetic arrangements and revealed a
degree of magnetic glassy state at the same time.10
Among the precursors [Fe(L)(CN)x]y-, molecular building
bricks with L ) tridentate ligand and x ) 3 can have facial
and meridional configurations relying on the relative disposi-
tion of the three cyanide groups around the FeIII center. Facial
FeIII tricyanide precursors with blocking groups, hydrot-
ris(pyrazolyl)borate (Tp), hydrotris(3,5-dimethylpyrazol-1-
yl)borate (Tp*), tetra(pyrazol-1-yl)borate (pzTp), and 1,3,5-
triaminocyclohexane (tach), were frequently utilized to
generate a number of magnetic systems with molecular and
1D chain structures.11 On the contrary, magnetic entities
fabricated by mer-[FeIII(L)(CN)3]- are still limited; they
contain chelating ligands, bis(2-pyridylcarbonyl)amidate
anion (bpca),12 8-(pyridine-2-carboxamido)quinoline anion
(pcq),13 8-(pyrazine-2-carboxamido)quinoline anion (pzcq),14
and 8-(5-methylpyrazine-2-carboxamido)quinoline anion
(mpzcq).15 However, to date, only a few Mn(II)-Fe(III) and
Mn(III)-Fe(III) bimetallic complexes based on mer-FeIII
cyanides were characterized structurally and magnetically.12-15
Herein, we report the syntheses, structures, and magnetic
properties of a dimer, [Fe(qcq)(CN)3][Mn(3-MeOsalen)-
(H2O)] ·2H2O [2·2H2O; 3-MeOsalen ) N,N′-ethylenebis(3-
methoxysalicylideneiminato) dianion], and three one-dimen-
sional (1D) zigzag chains, [Fe(qcq)(CN)3][Mn(5-Clsalen)]·
3H2O [3 · 2MeOH; 5-Clsalen ) N,N′-ethylenebis(5-chlo-
rosalicylideneiminato) dianion], [Fe(qcq)(CN)3][Mn(5-Br-
salen)]·2MeOH [4·2MeOH; 5-Brsalen ) N,N′-ethylenebis-
(5-bromosalicylideneiminato) dianion], and Fe(qcq)(CN)3]-
[Mn(salen)] · MeCN · H2O [5 · MeCN; salen ) N,N′-ethyl-
enebis(salicylideneiminato) dianion], using a newly designed
molecular precursor (PPh4)[Fe(qcq)(CN)3] [1; qcq ) 8-(2-
quinolinecarboxamido)quinoline anion]. Their crystal packing
diagrams are composed of extensive noncovalent forces such
as hydrogen bonding and π-π contacts, thus affording
higher-dimensional structures. Magnetic data show that
antiferromagnetic interactions are present between magnetic
centers through cyanide bridges in 2-5, which are in contrast
with most cyanide-linked FeIII-MnIII bimetallic systems.
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(b) Pradhan, R.; Desplanches, C.; Guionneau, P.; Sutter, J.-P. Inorg.
Chem. 2003, 42, 6607. (c) Shores, M. P.; Sokol, J. J.; Long, J. R.
J. Am. Chem. Soc. 2002, 124, 2279. (d) Ruiz, E.; Rodr´ıguez-Fortea,
A.; Alvarez, S.; Verdaguer, M. Chem.sEur. J. 2005, 11, 2135. (e)
Visinescu, D.; Desplanches, C.; Imaz, I.; Bahers, V.; Pradhan, R.;
Villamena, F. A.; Guionneau, P.; Sutter, J.-P. J. Am.Chem. Soc. 2006,
128, 10202. (f) Lim, J. H.; You, Y. S.; Yoo, H. S.; Yoon, J. H.; Kim,
J. I.; Koh, E. K.; Hong, C. S. Inorg. Chem. 2007, 46, 10578. (g) Lim,
J. H.; Kang, J. S.; Kim, H. C.; Koh, E. K.; Hong, C. S. Inorg. Chem.
2006, 45, 7821. (h) You, Y. S.; Yoon, J. H.; Lim, J. H.; Kim, H. C.;
Hong, C. S. Inorg. Chem. 2005, 44, 7063. (i) You, Y. S.; Kim, D.;
Do, Y.; Oh, S. J.; Hong, C. S. Inorg. Chem. 2004, 43, 6899.
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Ohkoshi, S.-i.; Hashimoto, K. J. Am. Chem. Soc. 2000, 122, 2952.
(b) Song, Y.; Zhang, P.; Ren, X.-M.; Shen, X.-F.; Li, Y.-Z.; You,
X.-Z. J. Am. Chem. Soc. 2005, 127, 3708. (c) Lim, J. H.; Yoon, J. H.;
Kim, H. C.; Hong, C. S. Angew. Chem., Int. Ed. 2006, 45, 7424. (d)
Freedman, D. E.; Bennett, M. V.; Long, J. R. Dalton Trans. 2006,
2829. (e) Bonadio, F.; Gross, M.; Stoeckli-Evans, H.; Decurtins, S.
Inorg. Chem. 2002, 41, 5891.
Experimental Section
Reagents. Mn Schiff bases were synthesized according to a
modified literature procedure.16 All chemicals and solvents in the
synthesis were of reagent grade and used as received. All manipula-
tions were performed under aerobic conditions.
(7) Gatteschi, D.; Sessoli, R. Angew. Chem., Int. Ed. 2003, 42, 268.
(8) (a) Lescoue¨zec, R.; Toma, L. M.; Vaissermann, J.; Verdaguer, M.;
Delgado, F. S.; Ruiz-Pe´rez, C.; Lloret, F.; Julve, M. Coord. Chem.
ReV. 2005, 249, 2691. (b) Clerac, R.; Miyasaka, H.; Yamashita, M.;
Coulon, C. J. Am. Chem. Soc. 2002, 124, 12837. (c) Coulon, C.;
Miyasaka, H.; Cle´rac, R. Struct. Bonding (Berlin) 2006, 122, 163.
(9) (a) Yoon, J. H.; Lim, J. H.; Choi, S. W.; Kim, H. C.; Hong, C. S.
Inorg. Chem. 2007, 46, 1529. (b) Wang, S.; Ferbinteanu, M.;
Yamashita, M. Inorg. Chem. 2007, 46, 610. (c) Ni, W.-W.; Ni, Z.-H.;
Cui, A.-L.; Liang, X.; Kou, H.-Z. Inorg. Chem. 2007, 46, 22. (d)
Matsumoto, N.; Sunatsuki, Y.; Miyasaka, H.; Hashimoto, Y.; Luneau,
D.; Tuchagues, J.-P. Angew. Chem., Int. Ed. 1999, 38, 171.
(10) (a) Wang, Z.-X.; Li, X.-L.; Wang, T.-W.; Li, Y.-Z.; Ohkoshi, S.-i.;
Hashimoto, K.; Song, Y.; You, X.-Z. Inorg. Chem. 2007, 46, 10990.
(b) Liu, W.; Wang, C.-F.; Li, Y.-Z.; Zuo, J.-L.; You, X.-Z. Inorg.
Chem. 2006, 45, 10058. (c) Liu, X.-T.; Wang, X.-Y.; Zhang, W.-X.;
Cui, P.; Gao, S. AdV. Mater. 2006, 18, 2852. (d) Kim, J.; Han, S.;
Pokhodnya, K. I.; Migliori, J. M.; Miller, J. S. Inorg. Chem. 2005,
44, 6983. (e) Li, D.-F.; Zheng, L.-M.; Zhang, T.-Z.; Huang, J.; Gao,
S.; Tang, W.-X. Inorg. Chem. 2003, 42, 6123. (f) Boskovic, C.;
Bircher, R.; Tregenna-Piggott, P. L. W.; Gudel, H. U.; Paulsen, C.;
Wernsdorfer, W.; Barra, A.-L.; Khatsko, E.; Neels, A.; Stoeckli-Evans,
H. J. Am. Chem. Soc. 2003, 125, 14046.
(11) (a) Liu, W.; Wang, C.-F.; Li, Y.-Z.; Zuo, J.-L.; You, X.-Z. Inorg.
Chem. 2006, 45, 10058. (b) Wen, H.-R.; Wang, C.-F.; Song, Y.; Gao,
S.; Zuo, J.-L.; You, X.-Z. Inorg. Chem. 2006, 45, 8942. (c) Gu, Z.-
G.; Yang, Q.-F.; Liu, W.; Song, Y.; Li, T.-Z.; Zuo, J.-L.; You, X.-Z.
Inorg. Chem. 2006, 45, 8895. (d) Wang, S.; Zuo, J.-L.; Zhou, H.-C.;
Choi, H. J.; Ke, Y.; Long, J. R.; You, X.-Z. Angew. Chem., Int. Ed.
2004, 43, 5940. (e) Li, D.; Parkin, S.; Wang, G.; Yee, G. T.; Prosvirin,
A. V.; Holmes, S. M. Inorg. Chem. 2005, 44, 4903. (f) Li, D.; Parkin,
S.; Wang, G.; Yee, G. T.; Cle´rac, R.; Wernsdorfer, W.; Holmes, S. M.
J. Am. Chem. Soc. 2006, 128, 4214. (g) Yang, J. Y.; Shores, M. P.;
Sokol, J. J.; Long, J. R. Inorg. Chem. 2003, 42, 1403. (h) Wang, S.;
Zuo, J.-L.; Gao, S.; Song, Y.; Zhuo, H.-C.; Zhang, Y.-Z.; You, X.-Z.
J. Am. Chem. Soc. 2004, 126, 8900.
(12) Lescoue¨zec, R.; Vaissermann, J.; Toma, M.; Carrasco, R.; Lloret, F.;
Julve, M. Inorg. Chem. 2004, 43, 2234.
(13) Ni, Z.-H.; Kou, H.-Z.; Zhang, L.-F.; Ni, W.-W.; Jiang, Y.-B.; Cui,
A.-L.; Ribas, J.; Sato, O. Inorg. Chem. 2005, 44, 9631.
(14) Kim, J. I.; Yoo, H. S.; Koh, E. K.; Kim, H. C.; Hong, C. S. Inorg.
Chem. 2007, 46, 8481.
(15) Kim, J. I.; Yoo, H. S.; Koh, E. K.; Hong, C. S. Inorg. Chem. 2007,
46, 10461.
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Polyhedron 2004, 23, 949.
Inorganic Chemistry, Vol. 48, No. 7, 2009 2957

Kim et al.
Synthesis. Caution! Perchlorate salts of metal compounds with
organic ligands are potentially explosiVe, and cyanides are toxic.
These materials should be handled with great caution.
Bomen MB-104 spectrometer. Magnetic susceptibilities for 2-5
were carried out using a Quantum Design SQUID (dc) and a PPMS
(ac) susceptometer. Diamagnetic corrections of 2-5 were estimated
from Pascal’s tables.
8-(2-Quinolinecarboxamido)quinoline (Hqcq). Quninaldic acid
(0.020 mol) and 8-aminoquinoline (0.020 mol) in pyridine (15 mL)
were stirred with heating up to 100 °C. Triphenyl phosphite (0.020
mol) was added to the resultant mixture and stirred at 100 °C for
4 h. The deep brown solution was cooled to room temperature and
concentrated in a vacuum. Crystalline solids were formed by adding
EtOH. The solids were collected with filtration, washed with EtOH,
and air-dried. Yield: 43%. Elem anal. (%) calcd for C19H13N3O: C,
76.2; H, 4.38; N, 14.0. Found: C, 76.4; H, 4.16; N, 13.9.
Fe(qcq)Cl2. To FeCl3 ·6H2O (8.54 mmol) in MeOH (60 mL)
were added Hqcq (8.54 mmol) and NaOH (8.54 mmol). The
reaction mixture was refluxed for 3 h, forming deep-green crystal-
line powders. The product was obtained with filtration and air-
dried. Yield: 85%. Elem anal. (%) calcd for C19H12Cl2FeN3O: C,
53.7; H, 2.85; N, 9.89. Found: C, 53.9; H, 2.87; N, 9.56.
K[Fe(qcq)(CN)3]. To a suspension of Fe(qcq)Cl2 (7.52 mmol)
in MeOH was slowly added KCN (22.5 mmol). The mixture was
refluxed for 3 h, precipitating dark-brown powders, which were
dried in a vacuum. The crude solids were recrystallized in MeOH.
Yield: 46%.
Crystallographic Structure Determination. X-ray data for 1-5
were collected on a Bruker SMART APEXII diffractometer
equipped with graphite monochromated Mo KR radiation (λ )
0.71073 Å). Preliminary orientation matrix and cell parameters were
determined from three sets of ω scans at different starting angles.
Data frames were obtained at scan intervals of 0.5° with an exposure
time of 10 s per frame. The reflection data were corrected for
Lorentz and polarization factors. Absorption corrections were
carried out using SADABS.17 The structures were solved by direct
methods and refined by full-matrix least-squares analysis using
anisotropic thermal parameters for non-hydrogen atoms with the
SHELXTL program.18 Lattice water molecules in 2 are significantly
disordered and could not be modeled properly; thus, the program
SQUEEZE,19 a part of the PLATON package20 of crystallographic
software, was used to calculate the solvent disorder area and remove
its contribution to the overall intensity data. All hydrogen atoms
except for hydrogens bound to water molecules were calculated at
idealized positions and refined with the riding models.
(PPh4)[Fe(qcq)(CN)3] (1). PPh4Br (1.2 mmol) dissolved in H2O
was added to K[Fe(qcq)(CN)3] (1.0 mmol) in H2O. Immediately,
brown powders were precipitated, which were filtered and air-dried.
The recrystallization was conducted by a MeOH/ether solvent pair.
Yield: 72%. Elem anal. (%) calcd for C46H32FeN6OP: C, 71.6; H,
4.18; N, 10.9. Found: C, 71.6; H, 4.25; N, 10.7.
[Fe(qcq)(CN)3][Mn(3-MeOsalen)(H2O)]·2H2O (2·2H2O). The
addition of [Mn(3-MeOsalen)(H2O)](ClO4) (0.050 mmol) in MeOH/
H2O (1:1) to 1 (0.050 mmol) in MeOH produced a brown solution.
This reaction mixture was stirred for 10 min, and then the filtrate
was allowed to remain undisturbed, producing brown crystals in
70% yield. Elem anal. (%) calcd for C40H36FeMnN8O8: C, 55.4;
H, 4.18; N, 12.9. Found: C, 55.6; H, 4.17; N, 12.6.
[Fe(qcq)(CN)3][Mn(5-Clsalen)]·2MeOH (3 ·2MeOH). A solu-
tion of [Mn(5-Clsalen)(H2O)]ClO4 (0.050 mmol) in MeCN/H2O (2:
1) was added to 1 (0.050 mmol) in MeOH. After 10 min of stirring,
the reaction solution was filtered and left undisturbed. Evaporation
of the filtrate finally gave brown crystals suitable for X-ray, which
were air-dried. Yield: 55%. Elem anal. (%) calcd for
C38H30Cl2FeMnN8O6 (3·3H2O): C, 52.1; H, 3.45; N, 12.8. Found:
C, 51.9; H, 3.22; N, 12.7.
[Fe(qcq)(CN)3][Mn(5-Brsalen)] ·2MeOH (4 ·2MeOH). To 1
(0.050 mmol) in MeOH was added a solution of [Mn(5-
Brsalen)(H2O)]ClO4 (0.050 mmol) in MeCN/H2O (2:1). The
solution was reacted with stirring for 10 min. The filtrate was then
slowly evaporated, producing brown crystals suitable for X-ray,
which were air-dried. Yield: 57%. Elem anal. (%) calcd for
C40H32Br2FeMnN8O5: C, 49.3; H, 3.31; N, 11.5. Found: C, 49.3;
H, 3.13; N, 11.4.
Results and Discussion
Synthesis and Characterization. A reaction of [Fe(qcq)-
(CN)3]- and the corresponding Mn Schiff bases in a 1:1
stoichiometric ratio produced brown crystals of 2-5. The
mixed solvents used in the synthesis play a crucial role in
making crystalline solids suitable for X-ray. The Cl-O
stretching vibrations present at the starting Mn Schiff bases
disappeared in the IR data of the products, implying that
the 1:1 reactions were completed. The alteration of Mn Schiff
bases led to the formation of the complexes with different
types of structures or structural parameters, which are
associated with the steric consequence of the side groups
on the Schiff bases in the crystal packing. The IR spectra
show that the characteristic CN bands are observed at 2123w
(sh) and 2108m cm-1 for 1, 2133m and 2116m cm-1 for 2,
2130m and 2116m cm-1 for 3, 2132m and 2117m cm-1 for
4, and 2119m cm-1 for 5. On the basis of the peaks of the
precursor, one of the peaks for 2-5 significantly moves
toward higher frequencies, indicating that CN ligands in the
peak shift are involved in coordination to metal ions. The
shift of the CN bands is related to the prevalent kinematic
effect, which leads to restriction of the motion of CN groups,
and electronic and geometric effects.21
Description of the Structures. The structures of 1-5 have
been characterized using single-crystal X-ray diffraction
techniques. Crystallographic data and the details of data
collection for all of the complexes are listed in Table 1, and
selected bond lengths and angles for 2-5 are summarized
[Fe(qcq)(CN)3][Mn(salen)]·MeCN (5 ·MeCN). A mixed solu-
tion of [Mn(salen)(H2O)]ClO4 (0.050 mmol) in MeCN/H2O (1:1)
was treated with 1 (0.050 mmol) in MeOH. Stirring of the reaction
solution for 5 min was followed by filtration and slow evaporation.
Brown crystals suitable for X-ray were precipitated over several
days and were air-dried. Yield: 42%. Elem anal. (%) calcd for
C40H31FeMnN9O4 (5·MeCN ·H2O): C, 59.1; H, 3.85; N, 15.5.
Found: C, 59.6; H, 3.68; N, 15.2.
(17) Sheldrick, G. M. SADABS; University of Go¨ttingen: Go¨ttingen,
Germany, 1994.
(18) Sheldrick, G. M. SHELXTL, version 5; Bruker AXS: Madison, WI,
1995.
(19) van der Sluis, P.; Spek, A. L. Acta Crystallogr. 1990, A46, 194.
(20) Spek, A. L. Acta Crystallogr. 1990, A46, 1.
(21) Dunbar, K. R.; Heintz, R. A. Prog. Inorg. Chem. 1997, 45, 283.
Physical Measurements. Elemental analyses for C, H, and N
were performed at the Elemental Analysis Service Center of Sogang
University. Infrared spectra were obtained from KBr pellets with a
2958 Inorganic Chemistry, Vol. 48, No. 7, 2009

Cyanide-Bridged FeIII-MnIII Bimetallic Complexes
Table 1. Crystallographic Data for 1-5
1
2
3·2MeOH
4·2MeOH
5·MeCN
formula
fw
C46H32FeN6OP
771.60
C40H32FeMnN8O6
831.53
C40H32Cl2FeMnN8O5
886.43
C40H32Br2FeMnN8O5
975.35
C40H29FeMnN9O3
794.51
cryst syst
space group
temp (K)
a (Å)
b (Å)
c (Å)
R (deg)
ꢀ (deg)
γ (deg)
V (Å3)
triclinic
P1
293
triclinic
P1
293
monoclinic
P21/c
130
10.0113(3)
14.1801(4)
26.7347(7)
monoclinic
P21/c
130
10.0064(2)
14.2657(3)
26.9395(7)
orthorhombic
P212121
130
13.0638(4)
13.5574(3)
20.3649(5)
j
j
9.3047(4)
14.7946(7)
14.8284(7)
109.4130(10)
97.306(2)
100.320(2)
1855.33(15)
2
13.961(3)
16.454(3)
19.703(4)
71.835(7)
74.846(7)
69.937(7)
3978.4(14)
4
90.860(2)
90.805(2)
3794.86(19)
4
1.552
0.913
1812
3845.19(15)
4
1.685
2.841
1956
3606.85(16)
4
1.463
0.805
1628
Z
dcalcd (g cm-3
)
1.381
0.496
798
1.388
0.738
1708
µ (mm-1
F(000)
)
reflns collected
unique reflns
19937
8208
65988
19421
35163
9207
36828
9560
17598
8484
goodness-of-fit
R1a [I > 2σ(I)]
wR2b [I > 2σ(I)]
1.043
0.879
0.0533
0.1021
1.006
0.0545
0.0996
0.972
0.0613
0.1285
1.049
0.0783
0.2121
0.1040
0.2168
b
a R1 ) ∑|Fo| - |Fc|/∑|Fc|. wR2 ) [∑ w(Fo - Fc2)2/Σw(Fo )2]1/2
.
2
2
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 2-5
2
Fe-Cbridge
1.956(4)-1.960(3)
1.885(2)-2.027(3)
2.273(2)-2.324(2)
174.2(3)-175.9(3)
144.6(2)-151.3(3)
Fe-Cnonbridge
Mn-Nbridge
1.943(4)-1.969(4)
Fe-N
2.287(3)-2.289(3)
Mn-Oterminal
Fe-Cbridge-Nbridge
Mn-Nbridge-Cbridge
Fe-Cnonbridge-Nnonbridge
173.2(3)-178.2(3)
3
4
5
Fe(1)-Cbridge
1.930(4)-1.960(4)
1.907(3)-2.009(3)
174.6(3)-176.2(3)
147.7(3)-161.4(3)
Fe(1)-Cnonbridge
Mn(1)-Nbridge
1.967(4)
2.280(3)-2.285(3)
177.2(3)
Fe(1)-N
Fe(1)-Cbridge-Nbridge
Mn(1)-Nbridge-Cbridge
Fe(1)-Cnonbridge-Nnonbridge
Fe(1)-Cbridge
Fe(1)-N
Fe(1)-Cbridge-Nbridge
Mn(1)-Nbridge-Cbridge
1.926(7)-1.964(6)
1.900(6)- 2.008(6)
175.0(5)-176.3(6)
147.7(5)-159.9(5)
Fe(1)-Cnonbridge
1.971(7)
2.283(6)-2.291(5)
177.3(6)
Mn(1)-Nbridge
Fe(1)-Cnonbridge-Nnonbridge
Fe(1)-Cbridge
1.934(5)-1.970(5)
1.889(6)-2.022(5)
174.1(5)-175.8(4)
149.3(5)-153.5(5)
Fe(1)-Cnonbridge
1.960(6)
2.297(5)-2.298(5)
179.0(6)
Fe(1)-N
Mn(1)-Nbridge
Fe(1)-Cbridge-Nbridge
Mn(1)-Nbridge-Cbridge
Fe(1)-Cnonbridge-Nnonbridge
in Table 2. The crystal structure of 1 is illustrated in Figure
S1 (Supporting Information).
Å.12-15 The Fe-C-N angles remain almost linear, with the
maximum deviations from 180° being 6.4° for Fe1 and 6.2°
for Fe2. A Jahn-Teller distortion is evident, with a Mn
octahedron judged by the shorter equatorial Mn-N(O)
distances [mean Mn-N(O) ) 1.93(6), 1.92(6) Å] than those
of the apical Mn-N(O) distances [Mn1-N3 ) 2.293(4) Å,
Mn1-O6 ) 2.275(3) Å, Mn2-N11 ) 2.288(4) Å, Mn2-O12
) 2.323(3) Å]. The bridging Mn-N-C angles correspond
to 145.0(3)° for Mn1-N3-C3 and 151.8(4)° for Mn2-
N11-C43. The intrachain Fe-Mn distances through the CN
linkage are 5.1243(14) Å for Fe1-Mn1 and 5.1841(15) Å
for Fe2-Mn2.
Complex 2. There exist two dimers within the unit cell
with slightly different structural parameters. Figure 1 depicts
a representative molecule within the cell of 2. The dimeric
unit is constructed from the anionic precursor [Fe(qcq)-
(CN)3]- and the cationic [Mn(3-MeOsalen)]+ part bridged
by the cyanide ligand. The structural propagation is blocked
by the coordination of one water molecule to one of the
binding sites of the Mn Schiff base. In the crystal structure,
the Fe geometry can be described as distorted octahedral,
consisting of three C atoms from CN ligands and three N
atoms from qcq. The mean Fe-C(cyanide) bond length is
1.95(1) Å. A strong σ-donor effect of the deprotonated amide
is responsible for the shorter Fe-N(amide) bond distances
[Fe1-N5 ) 1.886(4) Å, Fe2-N13 ) 1.900(4) Å] compared
to those of the other Fe-N lengths ranging 1.982-2.027
In the extended structure of 2 (Figure 2), dimeric moieties
are linked by hydrogen bonds among coordinated water
molecules and oxygen atoms of methoxy and phenoxy groups
(O · · · O ) 2.854-3.096 Å) as well as π-π interactions
between aromatic rings of qcq ligands. The combination of
Inorganic Chemistry, Vol. 48, No. 7, 2009 2959

Kim et al.
Figure 3. Molecular view of 3 with the selected atom-labeling scheme.
Symmetry transformations used to generate equivalent atoms: a ) -x +
1, y - 0.5, -z + 0.5; b ) -x + 1, y + 0.5, -z + 0.5.
Figure 1. Molecular view of 2 with the selected atom-labeling scheme.
The colors represent Fe in pink, Mn in green, N in blue, O in red, and C
in gray.
Mn-N(O) distances [mean Mn-N(O) ) 1.94(6) Å for 3
and 1.95(6) Å for 4] and axial Mn-N lengths [Mn1-N1 )
2.280(3) Å, Mn1a-N2 ) 2.285(3) Å for 3 and Mn1-N2 )
2.291(5) Å and Mn1c-N1 ) 2.283(6) Å for 4; a ) 1 - x,
-0.5 + y, 0.5 - z; c ) -x, 0.5 + y, 0.5 - z] demonstrates
the presence of the Jahn-Teller effect of a Mn octahedron.
ThebridgingMn-N-Canglesare147.7(3)°forMn1-N1-C1
and 161.4(3)° for Mn1a-N2-C2 (3) and 147.7(5)° for
Mn1c-N1-C1 and 159.9(5)° for Mn1-N2-C2 (4). The
intrachain Fe-Mn distances through the CN bridges are
5.1608(8) Å for Fe1-Mn1 and 5.2978(8) Å for Fe1-Mn1a
(3) and 5.1616(13) Å for Fe1-Mn1 and 5.2950(12) Å for
Fe1-Mn1c (4).
The extended structures of 3 and 4 are established by π-π
contacts between benzene rings of aminoquinoline groups
of qcq on adjacent chains (Figures 5 and S2). The centroid
distances are 3.672 Å for 3 and 3.625 Å for 4. The shortest
Fe-Fe distance through the noncovalent interactions is 8.992
Å for 3 and 9.024 Å for 4. Hydrogen bonds among OH
the noncovalent forces results in the construction of a two-
dimensional (2D) architecture. The shortest interdimer M-M
distances through the π-π contacts are 8.577 Å for
Fe1-Fe1, 9.066 Å for Fe2-Fe2, and 9.113 Å for Fe1-Fe2,
while those via the hydrogen bonds are 4.842 Å for
Mn1-Mn1and 4.943 Å for Mn2-Mn2.
Complexes 3 and 4. The structures of 3 and 4 can be
seen as a zigzag chain formed by the precursor anion and
the [Mn(5-Xsalen)]+ (X ) Cl and Br) cation (Figures 3 and
4). The bridging cyanides (C1-N1 and C2-N2) are used
as bridges to Mn centers in a cis mode. The mean
Fe-C(cyanide) bond length of 1.95(2)° for 3 and 4 is
identical to 2. The Fe-N(amide) bond distances are 1.907(3)
Å for 3 and 1.900(6) Å for 4, smaller than the other Fe-N
lengths, which are concerned with a strong σ-donor effect
of the deprotonated amide. The maximal deviations of the
Fe-C-N angles from linearity are similar, 5.4° for 3 and
5° for 4. The apparent disparity between the equatorial
Figure 2. Extended structure of 2 displaying π-π interactions between quinoline rings present in adjacent dimers as well as hydrogen bonds between
coordinated water molecules and oxygen groups of the Schiff bases.
2960 Inorganic Chemistry, Vol. 48, No. 7, 2009

Cyanide-Bridged FeIII-MnIII Bimetallic Complexes
apical Mn-N(O) distances [Mn1-N3 ) 2.298(5) Å and
Mn1e-N1 ) 2.297(5) Å; e ) 0.5 + x, 0.5 - y, -z] arise
from the Jahn-Teller distortion of a Mn octahedron. The
Mn-N-C angles in the bridging pathways are equal to
153.5(5)° for Mn1-N3-C3 and 149.3(5)° for Mn1e-N1-C1.
The intrachain Fe-Mn distances through the CN bridges are
5.2276(13) Å for Fe1-Mn1 and 5.2015(12) Å for Fe1-Mn1e.
The overall structure of 5 in the crystal packing is formed
by extensive π-π interactions between chains (Figure 7).
In the view generated in the direction of the arrow, the π-π
interactions between benzene rings of 8-aminoquinoline
groups and pyridyl rings of quinoline groups bring about
the construction of a 2D layer (Figure 7b). The centroid
distance through the contacts is 3.586 Å, and the shortest
Fe-Fe distance is 8.158 Å. In the other view in the direction
of the arrow, a 2D sheet is built up with the π-π stackings
of different types of quinoline rings residing in nearby chains
(Figure 7c). The coordinative and noncovalent bonds eventu-
ally give rise to a 3D network structure.
Figure 4. Molecular view of 4 with the selected atom-labeling scheme.
Symmetry transformations used to generate equivalent atoms: c ) -x, y +
0.5, -z + 0.5; d ) -x, y - 0.5, -z + 0.5.
Magnetic Properties of 1. The magnetic data of 1 were
collected in the temperature range 2-300 K and 1000 G, as
depicted in Figure S3 (Supporting Information). The ꢁmT
value is equal to 0.786 cm3 K mol-1 at 300 K, which is much
larger than the spin-only value (0.375 cm3 K mol-1) for a
noncoupled SFe ) 1/2 but consistent with those reported for
low-spin Fe(III) analogues.14,22a The ꢁmT behavior on
lowering the temperature is typical of octahedral low-spin
groups of methanols and oxygens of carbonyl groups on qcq
are present.
Complex 5. The structure of 5 comprises the Fe tricyanide
precursor and the [Mn(salen)]+ moiety (Figure 6). Unlike 2,
the use of salen without methoxy groups in the 3- position
of the Schiff base affords a zigzag chain, which is generated
by the coordination of two cyanides (C1-N1 and C3-N3)
in a cis mode to Mn centers. It is noted that the presence or
absence of the side groups (Cl or Br) on salen in the 5-
position does not change the overall chain structure. The
mean Fe-C(cyanide) bond length of 1.95(2) Å for 5 is the
same as that for 2. The shorter Fe-N(amide) bond distances
of Fe1-N5 ) 1.889(6) Å than those of the other Fe-N
lengths are due to a strong σ-donor effect of the deprotonated
amide. The maximal deviation of the Fe-C-N angles from
linearity is 5.9° for Fe1. The short equatorial Mn-N(O)
distances [mean Mn-N(O) ) 1.94(6) Å] and the elongated
Fe(III) systems with the T2g ground term.14,22
2
Magnetic Properties of 2. The magnetic susceptibility
data per FeMn of 2 were measured at a field of 1000 G and
temperatures of 2-300 K, as shown in Figure 8. The ꢁmT
value at 300 K is 3.18 cm3 K mol-1, which is slightly smaller
than the spin-only one (3.38 cm3 K mol-1) expected for
independent FeIII (SFe ) 1/2) and MnIII spins (SMn ) 2). A
slow decrease in ꢁmT designates the operation of antiferro-
magnetic interactions between the magnetic centers. The
high-temperature data (T > 10 K) were fitted using the
Figure 5. Extended 2D structure of 3 incorporating π-π contacts between benzene rings of aminoquinoline groups of qcq with a centroid distance of 3.672
Å. The shortest Fe-Fe distance through the noncovalent interactions is 8.992 Å.
Inorganic Chemistry, Vol. 48, No. 7, 2009 2961

Kim et al.
exchange value reveals the presence of intrachain antifer-
romagnetic interactions between MnIII and FeIII ions via the
CN bridges, which is consistent with the FeIII-MnIII systems
made of mer-Fe tricyanides14,15 but different from other
analogous FeIII-MnIII bimetallic systems exhibiting ferro-
magnetic alignments.24 It is evident that antiferromagnetic
interactions (zJ′) occur between dimeric units, which are
relevant with the presence of the π-π contacts and hydrogen
bonds in 2. As shown in the inset of Figure 8, the M(H)
data reveal that the experimental data are substantially below
the Brillouin curves derived from noncoupled spins within
a dimer (dashed line) and the intradimer antiferromagnetic
consequence of S ) SMn - SFe ) 3/2 (solid line). These
results demonstrate that prevalent antiferromagnetic interac-
tions are transmitted within a dimer and between dimers.
Magnetic Properties of 3 and 4. The magnetic suscep-
tibility data of 3 and 4 were collected at 1000 G in the
temperature range from 2 to 300 K, as shown in Figures 9
and 10, respectively. The ꢁmT values at 300 K are 3.56 cm3
K mol-1 (3) and 3.50 cm3 K mol-1 (4), which are a little
larger than the theoretical value calculated from the magneti-
cally dilute two-spin system (SFe, SMn) ) (1/2, 2). As the
temperature is lowered, ꢁmT decreases slowly and arrives at
a minimum of 2.42 cm3 K mol-1 and 2.18 cm3 K mol-1 at
Tmin ) 20 K for 3 and 4, respectively. Below Tmin, the ꢁmT
product increases up to 5.11 cm3 K mol-1 for 3 and 6.35
cm3 K mol-1 for 4 at 2 K. The overall magnetic behavior
resembles that of 3, typical of a ferrimagnetic situation within
a chain.25 The high-temperature data of T > 30 K obeys the
Curie-Weiss law with C ) 3.57 cm3 K mol-1 and θ )
-15.6 K (3) and C ) 3.32 cm3 K mol-1 and θ ) -19.5 K
(4), supporting the existence of antiferromagnetic couplings
between the paramagnetic centers.
Figure 6. Molecular view of 5 with the selected atom-labeling scheme.
Symmetry transformations used to generate equivalent atoms: e ) x + 0.5,
-y + 0.5, -z; f ) x - 0.5, -y + 0.5, -z.
Curie-Weiss law to give C ) 3.29 cm3 K mol-1 and θ )
-11.1 K, supporting the idea that dominant antiferromagnetic
couplings mediate between the metal ions.
Application of a dimer model (H ) -JSMn · SFe) under
consideration of the interdimer interactions (zJ′) to the data
(T > 7 K) yielded magnetic parameters of g ) 1.96, J )
-9.3 cm-1, and zJ′) -0.95 cm-1.
ꢁ ) (Ng2ꢀ2/3kT)[A/B]
A ) 15 + 52.5 exp(2.5x), B ) 4 + 6 exp(2.5x), x ) J/kT
ꢁm ) ꢁ/(1 - zJ’ꢁ/Ng2ꢀ2)
(1)
Inclusion of zero-field splitting parameter (D) was at-
tempted using the MAGPACK program,23 which provided
a minimal D value of less than 0.01 cm-1 with no virtual
changes in the other parameters. The observed magnetic
Figure 7. (a) Extended 3D structure of 5 formed by π-π interactions between chains. Parts b and c show 2D sheets constructed by coordinative 1D chains
and additional π-π stackings.
2962 Inorganic Chemistry, Vol. 48, No. 7, 2009

Cyanide-Bridged FeIII-MnIII Bimetallic Complexes
Figure 8. Plots of ꢁmT versus T at 0.1 T (main panel) and magnetization
vs H at 2 K (inset) for 2. The solid line in the main panel represents the
computed curve. The Brillouin curves derived from noninteracting magnetic
spins (dashed line) and S ) 3/2 (solid line) with g ) 2 are shown in the
inset.
Figure 11. Plots of in-phase (ꢁm′′ in main panel) and out-of-phase (ꢁm′ in
inset) components of ac magnetic susceptibility data measured at an ac field
of 5 G and an oscillating frequency of 3000 Hz for 3.
Figure 12. Plots of in-phase (ꢁm′′ in main panel) and out-of-phase (ꢁm′ in
inset) components of ac magnetic susceptibility data for 4.
Figure 9. Plots of ꢁmT vs T at 0.1 T (main panel) and magnetization vs H
at 2 K (inset) for 3. The solid line gives the fitted curve.
e
e
+ 1)]1/2, g ) (gMn + gFee)/2, δ ) (gMn - gFee)/2, u )
coth(Je/kT) - (kT/Je). The least-squares fittings conferred
roughly estimated parameters of gMn ) 1.99, gFe ) 2.52,
and J ) -10.5 cm-1 for 3 and gMn ) 1.90, gFe ) 2.48,
and J ) -11.8 cm-1 for 4.11e,28 The intrachain antifer-
romagnetic characters observed in 3 and 4 are consistent
with those for 2 and other FeIII-MnIII assemblies based
on mer-Fe tricyanide precursors.14,15 The field dependence
of the magnetization at 2 K was recorded in the field range
from 0 to 5 T, as illustrated in the insets of Figures 9 and
10. The magnetization values at 5 T correspond to 2.87
Nꢀ for 3 and 2.55 Nꢀ for 4, which are smaller than the
ferrimagnetic results of 3 Nꢀ calculated from MS
)
Figure 10. Plots of ꢁmT vs T at 0.1 T (main panel) and magnetization vs
H at 2 K (inset) for 4. The solid line gives the fitted curve.
g(SMn- SFe) with g ) 2. The low saturation magnetization
is related to the MnIII anisotropy.
We used the ferrimagnetic chain model to probe the
magnetic exchange coupling.26Fits were carried out with
magnetic data in the temperature range 15-300 K to preclude
Zeeman effect, zero-field splitting, and interchain magnetic
interactions.14,15,27
The ac magnetic susceptibility data in Figures 11 and 12
were examined at an ac field of 5 G and 3000 Hz. The
frequency dependences in the ac plots are not visible in 3
and 4. Noticeably, an obvious signal of the in-phase
component (ꢁm′) is observed at 2.3 K for 3 and 2.2 K for 4,
respectively, which are accompanied by peaks of the out-
of-phase part (ꢁm′′) in the ac data. This magnetic feature is
the signature of a long-range order in both complexes and
Nꢀ2 1 + u
1 - u
1 + u
e
ꢁmT )
g2
+ δ2
(2)
[
]
3k
1 - u
The parameters are as follows: gMn ) gMn[SMn(SMn
+
1)]1/2, gFee ) gFe[SFe(SFe + 1)]1/2, Je ) J[SMn(SMn + 1)SFe(SFe
Inorganic Chemistry, Vol. 48, No. 7, 2009 2963

Kim et al.
Figure 13. Plots of ꢁmT vs T at 0.1 T (main panel) and magnetization vs
H at indicated temperatures (inset) for 5. The solid line gives the fitted
curve.
Figure 15. Plots of relaxation rate versus reciprocal temperature (top) and
ln(τ) versus temperature (bottom) for 5. The solid lines represent the best
fits of the data to the Arrhenius equation and critical slowing-down equation,
respectively.
mol-1 at 2 K. This behavior is characteristic of a ferrimag-
netic arrangement resulting from the noncompensation of two
antiferromagnetically coupled spins. The higher value of Tmin
for 5 than those for 3 and 4 suggests that intrachain
antiferromagnetic interactions of 5 are stronger than those
of 3 and 4. The overall antiferromagnetic couplings in the
high-temperature range are confirmed by the Curie-Weiss
fitting to temperatures of T > 40 K, resulting in C ) 3.57
cm3 K mol-1 and θ ) -20.8 K.
Figure 14. Plots of ꢁm′ and ꢁm′′ (inset) versus T of 5 at an ac field of 3 G,
zero dc field, and several indicated frequencies.
can be understood in terms of enhanced magnetic couplings
between chains through the noncovalent interactions.29
Magnetic Properties of 5. The temperature dependence
of the magnetic susceptibility data per FeMn of 5 in the
temperature range 2-300 K is plotted in Figure 13. The ꢁmT
value of 3.25 cm3 K mol-1 at 300 K is somewhat smaller
than the spin-only one (3.38 cm3 K mol-1) anticipated from
noninteracting FeIII (SFe ) 1/2) and MnIII spins (SMn ) 2). A
gradual decay in ꢁmT supports the idea that antiferromagnetic
interactions take place between FeIII and MnIII spins. The
ꢁmT product reaches a minimum of 2.54 cm3 K mol-1 at
Tmin ) 40 K and then undergoes a sharp rise to 25.5 cm3 K
An analytical expression for the regular ferrimagnetic chain
system was employed in the temperature range 15-300 K.26
The roughly estimated result is equal to gMn ) 1.99, gFe
)
2.20, and J ) -14.1 cm-1.28 The negative value of J
indicates that antiferromagnetic couplings are operating
between FeIII and MnIII through the cyanide bridge. As seen
in the inset of Figure 13, the M(H) value of 2.94 Nꢀ at a
field of 7 T and temperatures of 2, 3, and 5 K shows that
the saturation magnetization is close to the ferrimagnetic
consequence of gS ) g(SMn - SFe) ) 3 Nꢀ assuming g ) 2.
The thermal variation of the ac magnetic susceptibility for
5 was inspected at zero dc field, an ac field of 3 G, and
(22) (a) Lescoue¨zec, R.; Lloret, F.; Julve, M.; Vaissermann, J.; Verdaguer,
M.; Llusar, R.; Uriel, S. Inorg. Chem. 2001, 40, 2065. (b) Toma, L. M.;
Lescoue¨zec, R.; Toma, L. D.; Lloret, F.; Julve, M.; Vaissermann, J.;
Andruh, M. J. Chem. Soc., Dalton Trans. 2002, 3171.
(23) Borras-Almenar, J. J.; Clemente-Juan, J. M.; Coronado, E.; Tsukerblat,
B. S. J. Comput. Chem. 2001, 22, 985.
(24) (a) Miyasaka, H.; Ieda, H.; Matsumoto, N.; Re, N.; Crescenzi, R.;
Floriani, C. Inorg. Chem. 1998, 37, 255. (b) Miyasaka, H.; Matsumoto,
N.; Re, N.; Gallo, E.; Floriani, C. Inorg. Chem. 1997, 36, 670. (c) Ni,
Z.-H.; Kou, H.-Z.; Zhang, L.-F.; Ge, C.; Cui, A.-L.; Wang, R.-J.; Li,
Y.; Sato, O. Angew. Chem., Int. Ed. 2005, 44, 7742. (d) Ni, Z.-H.;
Zhang, L.-F.; Tangoulis, V.; Wernsdorfer, W.; Cui, A.-L.; Sato, O.;
Kou, H.-Z. Inorg. Chem. 2007, 46, 6029. (e) Choi, H. J.; Sokol, J. J.;
Long, J. R. J. Phys. Chem. Solids 2004, 65, 839. (f) Miyasaka, H.;
Saitoh, A.; Abe, S. Coord. Chem. ReV. 2007, 251, 2622.
(27) (a) Zhang, Y.-Z.; Gao, S.; Wang, Z.-M.; Su, G.; Sun, H.-L.; Pan, F.
Inorg. Chem. 2005, 44, 4534. (b) Yang, C.-I.; Wernsdorfer, W.; Lee,
G.-H.; Tsai, H.-L. J. Am. Chem. Soc. 2007, 129, 456.
(28) Given that MnIII and FeIII spins are antiparallel, MnIII was assumed to
act as a classical spin carrier with SMn ) 2, leading to an effective
alternating chain with SMn ) 2 and SFe ) 1/2. The magnetic model
may be roughly applied to the system with the quantum spin
SFe ) 1/2.
(25) Yoon, J. H.; Kim, H. C.; Hong, C. S. Inorg. Chem. 2005, 44, 7714.
(26) Drillon, M.; Coronado, E.; Beltran, D.; Georges, R. Chem. Phys. 1983,
79, 449.
(29) Kou, H.-Z.; Gao, S.; Ma, B.-Q.; Liao, D.-Z. Chem. Commun. 2000,
713.
2964 Inorganic Chemistry, Vol. 48, No. 7, 2009

Cyanide-Bridged FeIII-MnIII Bimetallic Complexes
Table 3. Specific Structural Parameters (Mn-Ncyano Lengths and Mn-Ct N Angles in the Bridging Pathways) and Related Magnetic Coupling
Constants for Fe(III)-Mn(III) Systems Constructed from mer-FeIII Tricyanides
compounds
structure
Mn-Ncyano (Å)
Mn-Nt C (deg)
J (cm-1
)
ref
a
2
b
c
3
4
5
dimer
dimer
2.275(3)
164.1(2)
-17.2
-9.3
-17.2
-6.5
-10.5
-11.8
-14.1
15
this work
14
2.289(3), 2.287(3)
2.283(3), 2.263(3)
2.287(5), 2.298(5)
2.280(3), 2.285(3)
2.283(6), 2.291(5)
2.297(5), 2.298(5)
144.6(2), 151.3(3)
152.2(3), 158.3(3)
169.1(4), 154.3(5)
147.7(3), 161.4(3)
147.7(5), 159.9(5)
149.3(5), 153.5(5)
1D chain
1D chain
1D chain
1D chain
1D chain
15
this work
this work
this work
a [Fe(mpzcq)(CN)3][Mn(salen)(H2O)]·H2O. b [Fe(pzcq)(CN)3][Mn(salen)]·4H2O. c [Fe(mpzcq)(CN)3][Mn(salcy)]·MeOH·MeCN.
oscillating frequencies from 1 to 1000 Hz (Figure 14). The
in-phase component (ꢁm′) and out-of-phase part (ꢁm′′) in the
ac data definitely disclose the frequency dependence of the
maxima in the plots. The spin relaxation can be characterized
summation of the ferromagnetic term (JF) and the antifer-
romagnetic term (JAF) proportional to the overlap integral.33
On the basis of the DFT calculations conducted on the mer-
[Fe(qcq)(CN)3]- precursor (Figure S5, Supporting Informa-
tion), which are similar to the results for the mer-
[Fe(bpca)(CN)3]- complex,12 the main magnetic orbital of
mer-[Fe(qcq)(CN)3]- in the present system may be a dxz
orbital residing in the tricyanide plane where the x and z
axes pass through the N(5)-Fe(1)-C(1) and C2-Fe(1)-C(3)
vectors. Because all of the known FeIII-MnIII examples
bearing mer-Fe(III) tricyanides indicate antiferromagnetic
interactions via cyanide bridges (Table 3), which are contrary
to most cyanide-linked FeIII-MnIII bimetallic systems,24 it
seems reasonable that the orbital overlaps in this system,
which can occur between an FeIII dxz orbital and MnIII dπ
orbitals, are effective.24 This antiferromagnetic contribution
from the orbital overlap should overcome the ferromagnetic
using the quantitative measure equated as φ ) ∆Tmax
/
Tmax∆(log ω) in which Tmax is the peak temperature in ꢁm′
and ω is the angular frequency. The calculated value of φ is
0.018, which falls into canonical spin glasses.30 As shown
in the top panel of Figure 15, we applied the Arrhenius law
[τ ) τ0 exp(∆/kBT)] to the ꢁm′′ data, where τ stands for the
relaxation time, τ0 the pre-exponential factor, and ∆ the
energy barrier. The fitting result affords τ0 ) 2.4 × 10-36
s
and ∆/kB ) 168 K. The obtained τ0 value is quite small when
compared with those of typical SCMs.8 The frequency-
dependent maxima in ꢁm′′, often taken as a sign of a spin
glass system, are fitted to the dynamical slowing down for
spin glasses expressed as τ/τ0 ) [Tf/TG - 1]-zν, where τ is
the relaxation time, Tf the freezing temperature, TG the spin
glass temperature, and zν the critical exponent. The bottom
panel of Figure 15 points out that the best fit affords
parameters of τ0 ) 3.5 × 10-11 s, TG ) 1.9 K, and zν ) 9.4.
The obtained τ0 falls into the category of spin glasses, and
the zν value also conforms to the range from 4 to 12 of
canonical spin glasses.30,31 This characteristic reflects a glassy
state imbedded in 5. Compared with related extended
structures and magnetic natures of 3 and 4, a long-range
magnetic order in 5 may not be ruled out. Such glassy
behavior is likely associated with the single-ion anisotropy,
interchain magnetic interactions (dipolar or exchange cou-
pling), or some changes in solvent content. Similar behavior
was found in a 1D chain complex [MnIIITBrPP][TCNE]
where both magnetic competition between different magnetic
states on neighboring chains and partial solvent disorder/
loss were suggested to be the source of frustration and
randomness for spin glasses.32
2
contribution primarily from Fe dxz-Mn dz routes to give
the observed overall antiferromagnetic character in this
system. The factors, which affect the strength of the magnetic
exchange coupling, appear to be rather complicated; the
combined effects from the Mn-N(axial) bond lengths, the
bending of the Mn-Nt C-Fe skeletons, and the rotation
of the x and z axes for Mn(III) with respect to the xz plane
should be taken into consideration. For the dimeric systems,
it is manifest that the bending of the Mn-Nt C angles plays
a crucial role in diminishing the overlap and then reducing
the antiferromagnetic couplings. In contrast, the structural
parameters of the Mn-N(axial) lengths and Mn-Nt C
angles in the 1D materials are varied, and their magnetic
strengths are irregular. Therefore, all of the aforementioned
factors may be delicately incorporated in the magnetic results
of the current 1D family.
Conclusions
Magnetostructural Correlation. First of all, a simple
orbital scheme is considered to account for the underlying
magnetic natures of the prepared FeIII-MnIII compounds. The
total exchange coupling constant (J) can be provided by the
We have prepared the dimeric (2) and 1D chain complexes
(3-5) by using a newly made molecular precursor [Fe(qc-
q)(CN)3]- (1) with a meridional arrangement. The involve-
ment of noncovalent stackings (hydrogen bonding and π-π
contact) causes the construction of higher-dimensional
architectures. The magnetic data for all of the prepared
compounds undoubtedly reveal the operation of antiferro-
magnetic interactions between FeIII and MnIII centers medi-
ated by cyanide bridges, which may be assigned to the
enhanced orbital overlap in the systems constructed from
the mer-FeIII tricyanides. The bending of the Mn-Nt C
(30) Mydosh, J. A. Spin Glasses, An Experimental Introduction, Taylor &
Francis: London, 1993; pp 64-76.
(31) (a) Greedan, J. E.; Raju, N. P.; Maignan, A.; Simon, Ch.; Pedersen,
J. S.; Niraimathi, A. M.; Gmelin, E.; Subramanian, M. A. Phys. ReV.
B: Condens. Matter Mater. Phys. 1996, 54, 7189. (b) Laiho, R.;
Lahderanta, E.; Salminen, J.; Lisunov, K. G.; Zakhvalinskii, V. S.
Phys. ReV. B: Condens. Matter Mater. Phys. 2001, 63, 094405. (c)
Tholence, J. L. Physica B 1984, 126, 157. (d) Hong, C. S.; Kim, W. S.;
Chi, E. O.; Hur, N. H.; Choi, Y. N. Chem. Mater. 2002, 14, 1832.
(32) Rittenberg, D. K.; Sugiura, K.-i.; Sakata, Y.; Mikami, S.; Epstein, A. J.;
Miller, J. S. AdV. Mater. 2000, 12, 126.
(33) Kahn, O. Molecular Magnetism; VCH: Weinheim, Germany, 1993.
Inorganic Chemistry, Vol. 48, No. 7, 2009 2965

Kim et al.
angles obviously affects the magnetic strengths in the dimers;
however, the other structural parameters may be also taken
into account to understand the magnetic properties of the
1D chain complexes.
University was supported by the Acceleration Research
Program (Grant No. R17-2008-033-01000-0) and the Global
Research Network Program.
Supporting Information Available: X-ray crystallographic files
in CIF format for 1-5, additional structural and magnetic data,
and magnetic analyses for the complexes. This material is available
free of charge via the Internet at http://pubs.acs.org.
Acknowledgment. This work was supported by a Korea
Science and Engineering Foundation (KOSEF) grant (No.
R01-2007-000-10240-0) and Nuclear R&D Programs funded
by the Korea government (MOST). Work at Sungkyunkwan
IC802033Q
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