Novel coordination polymers with ferrocene-containing dicarboxylate ligand: Syntheses, crystal structures and properties

Article abstract of DOI:10.1016/j.jorganchem.2008.07.034

A new ferrocene-containing dicarboxylate ligand, L = 5-ferrocene-1,3-benzenedicarboxylic acid, has been prepared. Self-assembly of L, M(II) salts (M = Co and Zn) and chelating ligands dpa or phen (dpa = 2,2′-dipyridylamine and phen = 1,10-phen) gave rise to four new coordination polymers {[Co(L)(dpa)] · 2MeOH}_n (1), {[Zn(L)(dpa)] · 2MeOH}_n (2), {[Co(L)(phen)(H₂O)] · MeOH} (3), [Zn(L)(phen)(H₂O)] · MeOH (4). The isostructural complexes 1 and 2 possess 1D helical chain structures with 2₁ screw axes along the b-direction, and the right- and left-handed helical chains are alternate arrayed into 2D layer structures through hydrogen-bonding interactions; while isostructural complexes 3 and 4 are 1D linear chain structures with phen and ferrocene groups of L as pendants hanging on the different sides of the main chain. A structural comparison of complexes 1-4 demonstrated that the characteristics of subsidiary ligands and slight difference in coordination models of L play very important role in the construction of the complexes. In addition, the redox properties of complexes 1-4, as well as the magnetic properties of complexes 1 and 3 are also investigated.

Full text of DOI:10.1016/j.jorganchem.2008.07.034

Journal of Organometallic Chemistry 693 (2008) 3295–3302
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Novel coordination polymers with ferrocene-containing dicarboxylate ligand:
Syntheses, crystal structures and properties
a,
Xia Li a, Wei Liu b, Hong-Yun Zhang a, , Ben-Lai Wu
*
*
a Department of Chemistry, Zhengzhou University, Zhengzhou 450052, PR China
b Department of Chemistry and Chemical Engineering, Pingdingshan Engineering College, Pingdingshan 467001, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 13 May 2008
Received in revised form 24 July 2008
Accepted 29 July 2008
Available online 5 August 2008
A new ferrocene-containing dicarboxylate ligand, L = 5-ferrocene-1,3-benzenedicarboxylic acid, has been
prepared. Self-assembly of L, M(II) salts (M = Co and Zn) and chelating ligands dpa or phen (dpa = 2,20-
dipyridylamine and phen = 1,10-phen) gave rise to four new coordination polymers {[Co(L)
(dpa)] ꢀ 2MeOH}n (1), {[Zn(L)(dpa)] ꢀ 2MeOH}n (2), {[Co(L)(phen)(H2O)] ꢀ MeOH} (3), [Zn(L)(phen)
(H2O)] ꢀ MeOH (4). The isostructural complexes 1 and 2 possess 1D helical chain structures with 21 screw
axes along the b-direction, and the right- and left-handed helical chains are alternate arrayed into 2D
layer structures through hydrogen-bonding interactions; while isostructural complexes 3 and 4 are 1D
linear chain structures with phen and ferrocene groups of L as pendants hanging on the different sides
of the main chain. A structural comparison of complexes 1–4 demonstrated that the characteristics of
subsidiary ligands and slight difference in coordination models of L play very important role in the con-
struction of the complexes. In addition, the redox properties of complexes 1–4, as well as the magnetic
properties of complexes 1 and 3 are also investigated.
Keywords:
Ferrocene-containing dicarboxylate
Coordination polymer
1D helical chain
Co(II) complex
Zn(II) complex
Ó 2008 Published by Elsevier B.V.
1. Introduction
diversity and stability. Up to now, numerous ferrocene-containing
carboxylate complexes [6–8] have been reported, and among them,
Over past decades, investigation on metal-organic helical com-
plexes has received considerable interests not only for their simi-
larities to nucleic acids, proteins and many more natural or
artificial fiber-type derivatives, but also for their potential applica-
tions in asymmetric catalysis and non-linear optical materials [1].
Although many types of metal-organic helical complexes have
been reported [2], the self-assembly of helical structure is still a
challenging subject due to the strenuously selection of optimal
components. Recently, extensive studies have demonstrated that
a good strategy for the synthesis of low-dimensional metal com-
plex with helical structure can adopt two kinds of ligands such
as non-linear V-shaped dicarboxylate ligands and aromatic biden-
tate chelate ligands [3].
Ferrocene and its derivates extensively studied increasingly
become an active research area since it was found in 1951 [4].
For example, coordination chemists are strongly interested in
introducing ferrocene groups into a ligand framework with the
objective of generating materials possessing useful electrochemi-
cal, magnetic, optical and non-linear optical properties [5]. Very
recently, a new tendency is to incorporate carboxyl groups into a
ferrocene backbone so as to synthesize multidentate O-donor li-
gands and functional metal-organic materials with high structural
the reported ferrocenyl-based carboxylate ligands are mainly
based on ferrocenecarboxylic acid [6] and 1,10-ferrocenedicarbox-
ylic acid [7]. However, the complexes based on ferrocene-contain-
ing aromatic dicarboxylate ligands are rarely reported.
Taking these into consideration, a V-shaped ferrocene-containing
dicarboxylate ligand (L = 5-ferrocene-1,3-benzenedicarboxylic acid)
has been designed and synthesized. Self-assembly of L, M(II) salts
(M = Co and Zn) and chelating ligands dpa or phen (dpa = 2,20-dipyri-
dylamine and phen = 1,10-phen) gave rise to four new coordination
polymers {[Co(L)(dpa)] ꢀ 2MeOH}n (1), {[Zn (L)(dpa)] ꢀ 2MeOH}n (2),
{[Co(L)(phen) (H2O)] ꢀ MeOH} (3), [Zn(L)(phen)(H2O)] ꢀ MeOH (4).
Surprisingly, among them, two polymers with dpa ligands are 1D heli-
cal chain structures as we predicted, while the other two with phen
ligands do not form helices out of our prediction. To the best of our
knowledge, although many helical structures have been reported,
the helical structuresbaseon ferrocene-containing carboxylate is rare.
Here we want to report their preparations, crystal structures as well as
electrochemical, thermal and magnetic properties.
2. Experimental
2.1. Materials and methods
* Corresponding authors. Tel.: +86 0371 67763675 (H.-Y. Zhang).
E-mail addresses: wzhy917@zzu.edu.cn (H.-Y. Zhang), wbl@zzu.edu.cn (B.-L.
Wu).
All chemicals were obtained from commercial sources and used
without further purification. Melting point was taken on a XT-5
0022-328X/$ - see front matter Ó 2008 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2008.07.034

3296
X. Li et al. / Journal of Organometallic Chemistry 693 (2008) 3295–3302
microscope melting point apparatus. IR spectra were recorded on a
Bruker VECTOR22 spectrophotometer with KBr pellets in 400–
4000 cmꢁ1 region. Element analyses were performed with a Car-
lo-Erba 1106 elemental analyzer. 1H NMR spectra were recorded
on a Bruker DPX-400 spectrometer in d6-DMSO with TMS as an
internal standard. Mass spectra were measured on a LC-MSD-
Trap-XCT instrument. High-resolution mass spectra were mea-
sured on a Waters Q-T of Micro spectrometer. Thermal analysis
curves were scanned in a range of 30–800 °C with air atmosphere
on STA 409 PC thermal analyzer. Differential pulse voltammetry
studies were recorded with a CHI650 electrochemical analyzer uti-
lizing the three-electrode configuration of a GC working electrode,
a Pt auxiliary electrode, and a saturated calomel electrode as the
reference electrode. The measurements were performed in DMF
solution containing tetrabutyl ammonium perchlorate (TBAP,
0.1 mol Lꢁ1) as the supporting electrolyte. DPV curves were re-
corded at a 20 mV Sꢁ1 scan rate with pulse width of 50 ms and
sample width of 20 ms. The potential was scanned from +0.2 to
1.0 V. The temperature dependent magnetic measurements were
determined on a Quantum Design MPMS-5 magnetometer.
2.2.3. {[Zn (L)(dpa)] ꢀ 2MeOH}n (2)
A methanol solution (10 ml) of dpa (0.0198 g, 0.1 mmol) was
added dropwise to a methanol solution (5 ml) of Zn(NO3)2 ꢀ 6H2O
(0.0295 g, 0.1 mmol), and then a methanol solution (10 ml) of L
(0.035 g, 0.1 mmol) was added to the above mixture solution. With
triethylamine slowly diffusing into the mixture for a month, or-
ange block crystals suitable for X-ray single crystal diffraction anal-
ysis were obtained in 47% yield based on Zn. Anal. Calc. for
C
30H29FeN3O6Zn: C, 55.54; H, 4.51; N, 6.48. Found: C, 56.02; H,
4.48; N, 6.35%. IR (KBr, cmꢁ1): 3427 m, 3090 m, 1624 m, 1584 s,
1481 s, 1433 s, 1368 s,1236 m, 1160 m, 1024 m, 774 m, 732 m,
494 m.
2.2.4. {[Co(L)(phen)(H2O)] ꢀ MeOH}n (3)
A
mixture of Co(NO3)2 ꢀ 6H2O (0.0295 g, 0.1 mmol), phen
(0.0198 g, 0.1 mmol),
L (0.1 mmol), NaOH (0.2 mmol), MeOH
(5 ml) and water (5 ml) was sealed in a 15-ml Teflon-lined stain-
less steel reactor. The reactor was heated in an oven to 90 °C for
24 h and then slowly cooled to room temperature. Red needle-
shaped crystals were collected and dried in air (yield 63% based
on Co). Anal. Calc. for C31H26CoFeN2O6: C, 58.42; H, 4.11; N, 4.40.
Found: C, 57.53; H, 4.02; N, 4.24%. IR (KBr, cmꢁ1): 3421 s, 3096
m, 1613 s, 1563 s, 1448 s, 1396 s, 1107 m, 1041 m, 856 m, 828
m, 781 m, 730 s, 497 m.
2.2. Syntheses
2.2.1. 5-Ferrocene-1,3-benzenedicarboxylic acid (L)
Concentrated hydrochloric acid (20 ml) was added to a solution
of 5-amino-1,3-benzenedicarboxylic acid (5.43 g, 30.0 mmol) in
60 ml water. A solution of sodium nitrite (2.21 g, 32.0 mmol) in
20 ml water was then added slowly to the tempestuously stirring
mixture under a temperature range of 0–5 °C in an ice-bath for
20 min. The resulting diazo salt was allowed to stand for half an
hour before urea was employed to get rid of the excessive sodium
nitrite. Then the pale yellow thick solution was added to a solution
of ferrocene (5.58 g, 30.0 mmol) in diethyl ether (60 ml) with hexa-
2.2.5. {[Zn(L)(phen)(H2O)] ꢀ MeOH}n (4)
The complex 4 was prepared using the method similar to that
for complex 2 except that dpa was replaced by phen. Orange block
crystals suitable for X-ray single crystal diffraction analysis were
obtained in 42% yield based on Zn. Anal. Calc. for C31H26FeN2O6Zn:
C, 57.83; H, 4.07; N, 4.35. Found: C, 57.15; H, 3.96; N, 4.28%. IR
(KBr, cmꢁ1): 3429 s, 3080 m,1628 s, 1582 s, 1429 s, 1353 s, 1103
m, 847 m, 782 m, 725 s, 492 m.
decanyltrimethylammonium bromide (0.15 g, 0.5 mmol) as
a
2.3. X-ray structure determination
phase transfer catalysis, and the reaction mixture was allowed to
react for 4 h under 10 °C. Removing all the diethyl ether from the
mixture, the deposit was gathered and adjusted to a pH value of
13 by the addition of sodium hydroxide solution (8.0%). Filtering
to remove the superfluous ferrocene, the resultant dark-red solu-
tion was modulated with concentrated HCl to a pH value of 2,
and then the solution was cooled to produce crude solid product
which was purified by recrystallization in the methanol/water
mixing solvent (3:2). Finally, the orange crystals of pure 5-ferro-
cene-1,3-benzenedicarboxylic acid L (yield: 45%) was obtained.
HRMS: Calc. for C18H14FeO4 [M]+: 350.0242, found: 350.0255; IR
(KBr, cmꢁ1): 3430 m, 1704 vs, 1601 m, 1410 m, 1279 s; 1H NMR
(400 MHz) d ppm (DMSO): 13.32 (2H, s, –COOH), 8.30 (1H,
s,–ArH), 8.24 (2H, s, –ArH), 4.90 (2H, s, –Fc), 4.44(2H, s,), 4.05
(5H, s, –Fc); ESI-MS: [M]+: 350.1.
Crystallographic data for the title compounds was collected at
291(2) K on a Bruker SMART APEX-II CCD diffractometer equipped
with a graphite crystal and incident beam monochromator using
0
Mo Ka radiation (k = 0.71073 ÅA). Absorption corrections were ap-
plied by using SADABS. The structures were solved with direct
methods and refined with full-matrix least-squares techniques
on F2 using the SHELXTL program package [9]. All of the non-hydro-
gen atoms were refined anisotropically. The hydrogen atoms were
assigned with common isotropic displacement factors and in-
cluded in the final refinement by using geometrical restrains. Crys-
tal data are summarized in detail in Table 1. Selected bond lengths
and bond angles are listed in Table 2.
3. Results and discussion
3.1. Synthesis
2.2.2. {[Co(L)(dpa)] ꢀ 2MeOH}n (1)
A methanol solution (5 ml) of dpa (0.0198 g, 0.1 mmol) was
added dropwise to an aqueous solution (5 ml) of Co(NO3)2 ꢀ 6H2O
(0.0298 g, 0.1 mmol), and then a methanol solution (10 ml) of L
(0.035 g, 0.1 mmol) was added slowly to the above mixture solu-
tion. Finally, the pH value of the mixture was adjusted to about 7
with NaOH aqueous solution, and the resulting orange solution
was allowed to slowly evaporate at ambient temperature. Two
weeks later, dark-red block crystals suitable for X-ray single crystal
diffraction analysis were obtained in 56% yield based on Co. Anal.
Calc. for C30H29CoFeN3O6: C, 56.09; H, 4.55; N, 6.54. Found: C,
55.86; H, 4.50; N, 6.42%. IR (KBr, cmꢁ1): 3422 m, 3088 m, 1634
m, 1570 s, 1479 s, 1429 m, 1371 s, 1235 m, 1160 m, 1104 m,
1013 m, 773m, 732 m, 495 m.
The main ligands in all complexes are L and secondary ligands
dpa and phen are very similar, but the synthesis methods of 1–4
are very different. Complex 1 was obtained through the slow evap-
oration of solvent. Due to easily depositing under the similar con-
dition of 1, compounds 2 and 4 created from the slow diffusion of
triethylamine into the reaction systems. However, complex 3 was
synthesized through the hydrothermal method due to easily form-
ing polycrystal under the similar condition of 1. As reported in lit-
erature, most of the ferrocene-containing complexes are sensible
for light. However, the 5-ferrocene-1,3-benzenedicarboxylic acid
ligand and the corresponding complexes 1–4 are very stable under
the light and high temperature and pressure, which make them be
more easily handled in potential application. All of the complexes

X. Li et al. / Journal of Organometallic Chemistry 693 (2008) 3295–3302
3297
Table 1
Crystal data and structure refinement for complexes 1–4
Complex
1
2
3
4
Formula
C
30H29CoFeN3O6
C30H29FeN3O6Zn
648.78
Monoclinic
P21/c
10.549(2)
11.073(2)
24.245(5)
90
94.58(3)
90
2823.2(10)
4
1.526
1336
C31H26CoFeN2O6
637.32
C31H26FeN2O6Zn
643.76
Formula weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
642.34
Monoclinic
P21/c
10.478(2)
11.196(2)
24.220(5)
90
93.43(3)
Triclinic
Triclinic
ꢀ
ꢀ
P1
P1
9.6959(12)
10.0016(12)
14.2310(18)
94.555(2)
102.563(2)
92.556(2)
1340.0(3)
2
1.580
654
9.7240(19)
10.214(2)
14.320(3)
93.32(3)
103.32(3)
92.87(3)
1378.7(5)
2
a
(°)
b (°)
c
(°)
90
V (Å3)
2836.2(10)
4
1.504
1324
Z
Dcalc (g/cm3)
F(000)
1.551
660
h range (°)
Index range (°)
2.00–25.50
3.08–25.49
2.41–26.00
ꢁ11 6 h 6 11, ꢁ12 6 k 6 12,
ꢁ17 6 l 6 17
10453/5219 [0.0291]
2.31–26.00
ꢁ12 6 h 6 11, ꢁ13 6 k 6 13,
ꢁ26 6 l 6 29
15407/5263 [0.0175]
ꢁ12 6 h 6 12, ꢁ13 6 k 6 13,
ꢁ29 6 l 6 29
29115/5250 [0.0497]
ꢁ11 6 h 6 11, ꢁ12 6 k 6 12,
ꢁ17 6 l 6 17
Reflections collected/unique
10929/5351 [0.0407]
[R(int)
Goodness-of-fit on F2 (GOF)
R1, wR2 (I > 2 (I))
]
1.048
1.177
1.080
0.981
r
0.0395, 0.1057
0.0480, 0.1110
0.706, ꢁ0.657
0.0593, 0.1357
0.0674, 0.1404
0.656, ꢁ0.637
0.0450, 0.1155
0.0680, 0.1267
0.348, ꢁ0.612
0.0452, 0.0918
0.0845, 0.1071
0.508, ꢁ0.397
R1, wR2 (all date)
Largest difference in peak and
hole (e Åꢁ3
)
Table 2
Selected bond distances (Å) and angles (deg) for polymers 1–4
1
Co1–N3
Co1–N1
N1–Co1–O2
O3–Co1–O1
O1–Co1–N1
O1–Co1–O2
2.032(2)
2.063(3)
154.59(9)
102.24(9)
94.72(9)
60.08(7)
Co1–O3
Co1–O2
N3–Co1–O3
N3–Co1–N1
N3–Co1–O2
2.039(2)
Co1–O1
2.0466(19)
2.285(2)
138.92(10)
91.01(10)
97.62(9)
N3–Co1–O1
O3–Co1–N1
O3–Co1–O2
117.04(9)
97.58(9)
91.52(9)
2a
Zn1–O2
Zn1–N3
1.973(3)
2.068(3)
2.020(3)
109.14(12)
102.56(13)
90.73(12)
154.49(12)
Zn1–O4A
Zn1–O3A
O3–Zn1B
O2–Zn1–N1
O4A–Zn1–N3
O4A–Zn1–O3A
2.020(3)
2.403(3)
2.403(3)
28.78(13)
96.57(13)
8.24(11)
Zn1–N1
2.022(3)
O4–Zn1B
O2–Zn1–O4A
O2–Zn1–N3
O2–Zn1–O3A
N3–Zn1–O3A
O4A–Zn1–N1
N1–Zn1–N3
N1–Zn1–O3A
117.76(13)
91.80(13)
96.72(12)
3
Co1–O3
Co1–N1
2.091(2)
2.133(3)
Co1–O5
Co1–N2
2.096(3)
2.167(3)
Co1–O2
2.101(3)
O3–Co1–O5
O3–Co1–N1
O3–Co1–N2
N1–Co1–N2
99.79(11)
132.16(10)
88.54(11)
76.47(11)
O3–Co1–O2
O5–Co1–N1
O5–Co1–N2
87.80(10)
96.67(11)
171.56(11)
O5–Co1–O2
O2–Co1–N1
O2–Co1–N2
89.93(12)
136.92(10)
91.82(11)
4
Zn1–O2
Zn1–N2
2.027(3)
2.151(3)
Zn1–O3
Zn1–N1
2.080(3)
2.227(3)
Zn1–O5
2.098(3)
O2–Zn1–O3
O2–Zn1–N2
O2–Zn1–N1
N2–Zn1–N1
96.14(11)
124.37(11)
92.48(12)
75.78(11)
O2–Zn1–O5
O3–Zn1–N2
O3–Zn1–N1
98.35(11)
137.97(11)
93.43(11)
O3–Zn1–O5
O5–Zn1–N2
O5–Zn1–N1
90.68(11)
93.63(12)
167.95(12)
a
Symmetry transformations used to generate equivalent atoms: A, ꢁx + 1, y ꢁ 1/2, ꢁz + 1/2; B, ꢁx + 1, y + 1/2, ꢁz + 1/2.
are insoluble in common solvent, such as MeOH, EtOH, MeCN and
THF. To our knowledge, most of the reported ferrocene-containing
carboxylate complexes are based on the d10 metal centers (Zn, Cd
and Pb etc.), and few of those polymers contain Co metal centers
[7b].
detail for terseness. The coordination environments around metal
centers of complexes 2 and 4 as Supporting information are given.
3.2.1. {[Co(L)(dpa)] ꢀ 2MeOH}n (1)
A single crystal XRD study has revealed that complex 1 crystal-
lizes in a space group P21/c and has 1D helical chains. As shown in
Fig. 1, each five-coordinate Co(II) center is in a seriously distorted tri-
gonal bipyramid geometry, defined by two nitrogen atoms (N1, N3)
of dpa and three oxygen atoms (O1, O2 and O3) from carboxyl group
of twodifferentL. AtomsN1, O1 and O2 forman equatorialplane(the
3.2. Structure description
Because complexes 1 and 2 are isostructural, and 3 and 4 are
also isostructural, only the structures of 1 and 3 are discussed in

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X. Li et al. / Journal of Organometallic Chemistry 693 (2008) 3295–3302
deviation of center Co atom from the mean plane is about 0.0268 Å),
while atoms O3 and N3 occupy the axial position. The bond angle of
O1–Co–N3 is 138.93°. The Co–O distances range from 2.039(2) to
2.285(2) Å, while Co–N distances are 2.032(2) and 2.063(3) Å,
respectively, which is close to the related Co(II) coordination
allel with the separation of 3.80(6) Å, indicating weak p–p
stacking interactions, which makes the solid state structure more
stable.
3.2.2. {[Co(L)(phen)(H2O)] ꢀ MeOH} (3)
polymers Co2(O2CFcCO2)2(2,20-bpy)2(
l
2-OH2)2] ꢀ CH3OH.2H2O [7b],
The crystal structure analysis by X-ray diffraction demonstrates
ꢀ
[Co(Pht)(bpy)(H2O)3] ꢀ 3H2O [10] and [Co(PCPA)(IN)]n [11].
The dihedral angle between the carboxyl groups and the phenyl
ring are 166.2° and 71°, respectively. A visible twisting is observed
between the Cp ring and the phenyl ring to which is attached, with
the dihedral angle between them being 161.5°. No significant
deformation of the almost parallel Cp ring is observed. In each
dpa, the average deviation of the whole molecular plane is
0.0661 Å, and the dihedral angle between two pyridine rings is
7.9°.
Each ligand L serving as a bisconnector through its two car-
boxyl moieties bridges two Co atoms to afford an infinite 1D
chain. There exist two different coordination modes of the two
carboxyls: monodentate and chelate coordinations. The distance
of adjacent Co atoms separated by L is 9.16(9) Å. Notably the
1D chain structure is a helix with a pitch of 11.19(6) Å following
a 21 screw axis along the b-direction (Fig. 1). The dpa ligands are
alternately attached to both sides of the single-stranded helical
chain. Two adjacent helical chain with different handedness are
bridged by two types of hydrogen-bonds: one is N2–H2Aꢀ ꢀ ꢀO6
formed by the uncoordinated amino hydrogen atom of dpa and
the oxygen atom of lattice methanol molecule, and the other is
O6–H11ꢀ ꢀ ꢀO3 formed by the lattice CH3OH hydrogen atom and
the coordinated O atoms of the monodentate carboxyl group.
The N2–O6 and O6–O3 distances are 2.885(3) and 2.837(3) Å,
respectively. As a result of the alternate arrangement of the right-
and left-handed helical chains through interchained hydrogen-
that complex 3 crystallized in a space group P1. As shown in Fig. 3,
each Co(II) is also five-coordinated and located in a distorted trigo-
nal bipyramid geometry ligated by two nitrogen atoms from phen,
two oxygen atoms from two different carboxylate of L and one oxy-
gen atoms from coordinated water molecule. The O2, O3 and N1
atoms form an equatorial plane (the deviation of center Co atom
from the mean plane is about 0.0756 Å), and O5 and N2 occupy
the axial position (O5–Co1–N2 171.56(11)°). The Co–O distances
range from 2.091(2) to 2.101(3) Å, which is consistent with those
in complex 3, while the Co–N distances of 2.133 and 2.1671 Å
are slightly longer than those found in 3.
The phenyl ring and the cyclopentadienyl (Cp) are almost copla-
nar with the mean deviation from the plane being 0.0566 Å. The
two carboxylate groups have 5.4° and 158.7° dihedral angles with
the plane of corresponding linking phenyl rings, respectively. It is
clear that the phen ring is almost perpendicular to the plane of cor-
respondingly linked phenyl ring, and the dihedral angle between
them is 93.3°. No significant deformation of the almost parallel
Cp ring is observed.
In 3, each L adopt a bis(monodentate) coordination mode and
acts as a
l2-bridge linking two Co atoms to give an one-dimen-
sional linear chain. The distance of two adjacent Co atoms sepa-
rated by L is 10.00(2) Å, which is slightly longer than that in 1.
The ferrocene and phen hang on the different sides of the main
chain with phen rings or cp rings paralleling each other, respec-
bonding interactions,
a 2D mesomeric layer is fabricated
(Fig. 2). To the best of our knowledge, although a lot of helical
structures have been reported, the helical chain structures based
on ferrocene-containing carboxylate are extremely rare. In addi-
tion, the dpa ligands between the adjacent helical chains are par-
Fig. 1. (a) ORTEP drawing with heteroatom labeling scheme of 1D helical chain
structure of {[Co(L)(dpa)] ꢀ 2MeOH}n (1) (H atoms and uncoordinated solvent
moleculars are omitted for clarity). (b) Space-filling model of left-handed (left) and
right-handed (right) helical chains (H, Fc group and part of dpa atoms are omitted
for clarity).
Fig. 2. View of 2D supramolecular network in 1 forming through hydrogen-bond
alternately linking the right- and left-handed helices. The hydrogen-bonding
interactions between the chains are indicated as . . . (Fc group was omitted for
clarity).

X. Li et al. / Journal of Organometallic Chemistry 693 (2008) 3295–3302
3299
Fig. 3. ORTEP drawing with heteroatom labeling scheme of 1D lineal chain structure of {[Co(L)(phen)(H2O)] ꢀ MeOH} (3) (H atoms and uncoordinated solvent molecules are
omitted for clarity).
tively. The separations between the adjacent Co atoms, Fe atoms
and phen rings are all 10.00(2) Å. At opposite positions the
adjacent linear chains are further bridged to form a parallel double
chains through different O–Hꢀ ꢀ ꢀO (O–Hꢀ ꢀ ꢀO = 2.673–2.733 Å,
<O–Hꢀ ꢀ ꢀO = 165–176°) hydrogen-bond interactions, originating
from the coordinated water hydrogen atoms and lattice CH3OH
hydrogen atoms, respectively, to the uncoordinated oxygen of the
carboxylate group, or from the coordinated water hydrogen atoms
to the lattice CH3OH oxygen atoms (Fig. 4). Moreover, the double
chains are further extended to a layer network through the aro-
matic
p–p stacking interactions of the phen groups between the
adjacent layers (Fig. 5), and the closest distance between adjacent
aromatic rings is 3.32(2) Å.
Comparing the structures of 1–4, it is easy to conclude that
changing the subsidiary ligands may affect the architecture of
the complexes. In contrast to phen, although they are both chelat-
ing ligands, dpa with an excess amino-N atom displays more labil-
ity and plentiful hydrogen-bonding interactions. Moreover, the
bite angles (<N–M–N) of dpa and phen are very different, 91.0°
and 91.8° for 1 and 2, 76.5° and 75.8° for 3 and 4, respectively,
maybe which is the most important reason why the complexes
based on dpa are easily to form a 1D helical chain. Further, the
packing interactions in 1–4 are different. The 2D supurmolecular
network of complexes 1 and 2 are mainly supported by the hydro-
gen-bonding of dpa, while 3 and 4 are mainly supported by the
Fig. 5. 2D network of 3 showing the p–p stacking interactions between phen.
2 the two-connectors L link metal nodes with one carboxylate
monodentate coordination and the other chelate coordination
whereas in complexes 3 and 4 ligands L only act as bis(monoden-
p–p stacking interaction of phen. Moreover, in complexes 1 and
Fig. 4. The double linear chains bridged by the hydrogen-bonding in complex 3. The hydrogen-bonding interactions between the chains are indicated as . . .

3300
X. Li et al. / Journal of Organometallic Chemistry 693 (2008) 3295–3302
tate) bridges, and the slight difference in coordination models may
play a key role in the architectural variation.
assigned to the decomposition of ligand L and dpa groups (calcd.
65.94%). The left residue of 23.97% can be attributed to the forma-
tion of CoO and Fe2O3 (calcd. 24.10%). Similarly, the first decompo-
sition step starts at 90.7, 121 and 60 °C for 2–4, respectively,
corresponding with the weight lose of 9.38%, 7.32% and 4.63%,
respectively. Then the second step of weight losing takes place in
the temperature range of 323–500 °C for 2, 326–540 for 3 and
309–486 for 4, respectively, with the sharp weight lose of 64.89%
for 2, 66.03% for 3 and 65.19% for 4, respectively. Following contin-
uous heating, the smooth platforms were observed.
3.3. IR spectroscopy
The IR spectra of complexes 1 and 2 are similar, while those of
complexes 3 and 4 are also similar. The absence of absorption
bands at 1731–1651 cmꢁ1 where the –COOH is expected to appear
illustrates the complete deprotonation of L upon its coordination to
metal ions. For 1, the bands at 3087 and 495 cmꢁ1 (3090 and
494 cmꢁ1 for 2, 3096 and 497 cmꢁ1 for 3, 3080 and 492 cmꢁ1 for
4) are attributed to the typical characteristic
t
(C–H) and
t(Fe–Cp)
3.6. Redox properties
vibration of the ferrocenyl group [12]. The strong absorption bands
at 1570 and 1371 cmꢁ1 (1584 and 1368 cmꢁ1 for 2, 1563 and
1396 cmꢁ1 for 3, 1570 and 1371 cmꢁ1 for 4) are due to the asym-
The electrochemical behaviors of 1–4 and ligand L were studied
by differential pulse voltammetry at a GC working electrode in
DMF. Both L and the complexes show a single peak corresponding
to the single-electron Fc/Fc+ couple oxidation processes, with the
half-wave potential being 560, 562, 565, 564, 571 mV for L and
1–4, respectively. The electrochemical results show that coordi-
nated metal ions Co(II) and Zn(II) do not affect the potential of
the Fc/Fc+ couple in polymers 1–4. Similar condition also can be
found in other reported ferrocene-containing carboxylate com-
plexes, {Zn(FcCOO)2(bbbm)} ꢀ 2H2O}n [13], [Ba(OOCFcCOO)(H2O)]n
metric t t
as(COOꢁ) and symmetric as(COOꢁ) stretching vibrations.
The broad bands at 3420 cmꢁ1 belong to the typical band of hydro-
xyl group. In conclusion, the IR data are good agreement with the
X-ray analyses.
3.4. X-ray powder diffraction measurement
To confirm whether the analyzed crystal structures are truly
representative of the bulk materials, X-ray powder diffraction
(XRPD) experiments were carried out for complexes 1–4 at room
temperature (Fig. 6). Their peak positions are in good agreement
with each other, indicating the phase purity of the products. The
differences in intensity may be due to the preferred orientation
of the powder samples.
[7c] and {[Pb(l2
-g
2-OOCCH@(CH3)CFc)]ꢀMeOH}n [8a].
3.7. Magnetic properties
The temperature (T) dependencies of the magnetic susceptibil-
ity (vM) of complexes 1 and 3 were measured in the temperature
range 2–300 K under fixed fields of 1 kOe, and the magnetic sus-
ceptibilities vM and leff versus T plots are shown in Figs. 7 and 8,
respectively.
3.5. Thermogravimetric analysis (TGA)
To investigate their thermal stabilities, thermogravimetric anal-
yses (TGA) of 1–4 were carried out under air atmosphere with flow
rate of 60 mL minꢁ1 and heating rate of 10 °C minꢁ1. The TG anal-
yses reveal that the thermal decomposition behaviors of com-
plexes 1–4 were similar. For 1, it is stable up to 65 °C. A total
weight loss of 10.24% occurred in the temperature range of 65–
308 °C, probably corresponding to the remove of free methanol
molecules (calcd. 9.96%). The second obvious weight loss takes
place from 308 to 474 °C, and the weight loss is 65.79%, which is
For complex 1, the experimental
is 4.91 B, which is larger than the spin-only value of high-spin co-
balt(II), 3.87 B, indicating a typical contribution of the orbital
momentum for the 4T1g ground state. Upon cooling, the
eff gradu-
ally decreases to a value of 3.71
B at 2 K. As shown in the vꢁM1 ver-
sus T plot, all date follow the Curie–Weiss law closely with
C = 3.01 cm3 molꢁ1 K and h = ꢁ7.86 K. The negative value of h indi-
cates weak antiferromagnetic interactions between adjacent Co(II)
ions.
leff value at room temperature
l
l
l
l
Fig. 6. XRPD patterns for complexes 1–4: (bottom) calculated patterns from single crystal X-ray data; (top) measured patterns.

X. Li et al. / Journal of Organometallic Chemistry 693 (2008) 3295–3302
3301
phen with metal ions Co(II) or Zn(II) have been reported. The delib-
erate design and selection of the ligands is very useful to prepare the
complexes with desired architecture and properties. The subtle dif-
ference of the subsidiary ligands dpa and phen as well as the coor-
dination models of L result in substantial structural difference:
complexes 1 and 2 are 1D helix chains, while 3 and 4 are 1D linear
1.0
0.8
0.6
0.4
0.2
0.0
6
5
4
3
2
1
0
chains. Moreover, hydrogen-bond and
p–p stacking interaction
play very important role in the construction of supramolecular
architectures, which contribute to increasing the knowledge of
self-assembly processes and supramolecular self-organization.
The magnetic behavior of complexes 1 and 3 were investigated
and exhibited antiferromagnetic interactions. Further investigation
on the thermal properties of complexes 1–4 shows that all com-
plexes are stable enough until to 300 °C.
χ
0
50
100
150
200
250
300
Acknowledgements
T / K
Fig. 7. vM (s) and leff (h) vs. T plot with the theoretical fit (–) for 1.
We gratefully acknowledge financial support from the National
Natural Science Foundation of China (20771094, 20671083), the
Science and Technology Key Task of Henan Province
(0524270061) and the China Postdoctoral Science Foundation
(20070410877).
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
5
4
3
2
1
0
Appendix A. Supplementary material
CCDC 687273, 663361, 687272 and 663362 contains the sup-
plementary crystallographic data for 1, 2, 3 and 4. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via http://www.ccdc.cam.ac.uk/data_request/cif. Sup-
plementary data associated with this article can be found, in the
online version, at doi:10.1016/j.jorganchem.2008.07.034.
χ
References
0
50
100
150
200
250
300
T / K
[1] J.M. Lehn, Supramolecular Chemistry
Weinheim, 1995.
– Concepts and Perspectives, VCH,
[2] (a) Q.B. Bo, Z.X. Sun, G.L. Song, F. Li, G.X. Sun, J. Inorg. Organomet. Polym. 17
(2007) 615;
Fig. 8. vM (s) and leff (h) vs. T plot with the theoretical fit (–) for 3.
(b) S.Q. Zang, Y. Su, Y.Z. Li, Z.P. Ni, Q.J. Meng, Inorg. Chem. 45 (2006) 174;
(c) S. Sailaja, M.V. Rajasekharan, Inorg. Chem. 39 (2000) 4586;
(d) A. Erxleben, Inorg. Chem. 40 (2001) 412;
(e) T.D. Owens, f.J. Hollander, A.G. Oliver, J.A. Ellman, J. Am. Chem. Soc. 123
(2001) 1539;
(f) Y. Ma, Z.B. Han, Y.K. He, L.G. Yang, Chem. Commun. 40 (2007) 4107;
(g) S.D. Reid, A.J. Blake, C. Wilson, J.B. Love, Inorg. Chem. 45 (2006) 636;
(h) R.H. Wang, L.J. Xu, X.S. Li, Y.M. Li, Q. Shi, Z.Y. Zhou, M.C. Hong, A.S.C. Chan,
Eur. J. Inorg. Chem. (2004) 1595.
For complex 3, the experimental
is 4.72 B, which is larger than the spin-only value of high-spin co-
balt(II), 3.87
leff value at room temperature
l
l
B, indicating a typical contribution of the orbital
momentum for the 4T1g ground state. As the temperature lowered,
the leff gradually decreases to a value of 4.37 lB at 40 K, and then
decreases more rapidly at low temperatures, reaching a value of
3.12 lB at 2 K. As shown in the vꢁM1 versus T plot, all date follow
[3] (a) X.M. Chen, G.-F. Liu, Chem. Eur. J. (2002) 811;
(b) Y.G. Li, N. Hao, Y. Lu, E.B. Wang, Z.H. Kang, C.W. Hu, Inorg. Chem. 42 (2003)
3119;
the Curie–Weiss law closely C = 2.76 cm3 molꢁ1
K
and
h = ꢁ5.66 K. The negative value of h may be attributed to antiferro-
(c) Y.G. Li, H. Zhang, E.B. Wang, N. Hao, C.W. Hu, Y. Yan, D. Halld, New J. Chem.
26 (2002) 1619;
magnetic interactions between Co(II) ions.
(d) Y. Lu, E.B. Wang, M. Yuan, G.Y. Luan, Y.G. Li, H. Zhang, C.W. Hu, Y. Yao, Y.
Qin, Y. Chen, J. Chem. Soc., Dalton Trans. (2002) 3029.
[4] T.J. Kealy, P.L. Pauson, Nature 168 (1951) 1039.
[5] (a) R.D.A. Hudson, J. Organomet. Chem. 637–639 (2001) 47;
(b) C.J. Fang, C.Y. Duan, D. Guo, C. He, Q.J. Meng, Z.M. Wang, C.H. Yan, Chem.
Commun. (2001) 2540;
The susceptibility data of complexes 1 and 3 can be simulated
with the analytical equation (see below) reported by Hong et al.
[14].
Nb2g2SðS þ 1Þ 1 þ u
vMJ
¼
ð1Þ
(c) P.D. Beer, D.K. Smith, Prog. Inorg. Chem. 46 (1997) 1;
(d) Z.H. Wang, K.C. Chen, H. Tian, Chem. Lett. 5 (1999) 423;
(e) B. Bildstein, M. Schweiger, H. Angleitner, H. Kopacka, K. Wurst, K.H.
Ongania, M. Fontani, P. Zanello, Organomet. 18 (1999) 4286;
(f) C.J. Fang, C.Y. Duan, D. Guo, C. He, Q.J. Meng, Z.M. Wang, C.H. Yang, Chem.
Commun. (2001) 2540;
3kT
1 ꢁ u
h
i
h
i
JSðSþ1Þ
kT
JSðSþ1Þ
where u ¼ coth
ꢁ
kT
The best fit (assuming zJ = 0) of the experimental data to Eq. (1)
yielded
J = ꢁ0.09 cmꢁ1
,
g = 2.05,
R = 5.0 ꢂ 10ꢁ5
for
1,
(g) G. Li, Y.L. Song, H.W. Hou, L.K. Li, Y.T. Fan, Y. Zhu, X.R. Meng, L.W. Mi, Inorg.
Chem. 42 (2003) 913.
J = ꢁ0.33 cmꢁ1, g = 2.13, R = 4.0 ꢂ 10ꢁ5 for 3, the agreement factor
P
2
2
[6] (a) M.R. Churchill, Y.J. Li, D. Nalewajek, P.M. Schaber, J. Dorfman, Inorg. Chem.
24 (1985) 2684;
defined as R ¼ ½ðvMÞobsdꢃ—½ðvMÞcacldꢃ =½ðvMÞobsdꢃ :
(b) S.K.C. Kumara, S. Nagabrahmanandachari, K. Raghuraman, J. Organomet.
Chem. 587 (1999) 132;
(c) V. Chandrasekhar, S. Nagendran, S. Bansal, A.W. Cordes, A. Vij, Organomet.
21 (2002) 3297;
(d) V. Chandrasekhar, S. Nagendran, S. Bansal, M.A. Kozee, D.R. Powell, Angew.
Chem., Int. Ed. 39 (2000) 1833;
4. Conclusion
In this paper, four new complexes 1–4 constructed by 5-ferro-
cene-1,3-benzenedicarboxylic acid and accessorial ligands dpa or

3302
X. Li et al. / Journal of Organometallic Chemistry 693 (2008) 3295–3302
[8] (a) G. Li, H.W. Hou, L.K. Li, X.R. Meng, Y.T. Fan, Y. Zhu, Inorg. Chem. 42 (2003)
(e) H.W. Hou, L.K. Li, G. Li, Y.T. Fan, Y. Zhu, Inorg. Chem. 42 (2003) 3501;
(f) S.M. Lee, K.K. Cheung, W.T. Wong, J. Organomet. Chem. 506 (1996)
4995;
77;
(b) G. Li, H.W. Hou, Z.F. Li, X.R. Meng, Y.T. Fan, New J. Chem. 28 (2004) 1595;
(c) H.W. Hou, L.K. Li, Y. Zhu, Y.T. Fan, Y.Q. Qiao, Inorg. Chem. 43 (2004) 4767;
(d) L.K. Li, Y.L. Song, H.W. Hou, Y.T. Fan, Y. Zhu, Eur. J. Inorg. Chem. 16 (2005)
3238;
(g) A.L. Abuhijleh, C. Woods, J. Chem. Soc., Dalton Trans. 7 (1992) 1249.
[7] (a) G.L. Zheng, J.F. Ma, Z.M. Su, L.K. Yan, J. Yang, Y.Y. Li, J.F. Liu, Angew. Chem.,
Int. Ed. Eng. 43 (2004) 2409;
(b) X.R. Meng, H.W. Hou, G. Li, B.X. Ye, T.Z. Ge, Y.T. Fan, Y. Zhu, H. Sakiyama, J.
Organomet. Chem. 689 (2004) 1218;
(e) L.K. Li, J.P. Li, H.W. Hou, Y.T. Fan, Y. Zhu, Inorg. Chim. Acta 359 (2006)
3139.
(c) D. Guo, H. Mo, C.Y. Duan, F. Lu, Q.J. Meng, J. Chem. Soc., Dalton Trans. (2002)
2593;
(d) S.D. Christie, S. Subramanian, L.K. Thompson, M.J. Zaworotko, J. Chem. Soc.,
Chem. Commun. (1994) 2563;
(e) X.R. Meng, G. Li, H.W. Hou, H.Y. Han, Y.T. Fan, Y. Zhu, C.X. Du, J. Organomet.
Chem. 679 (2003) 153;
(f) Y.Y. Yang, W.T. Wong, Chem. Commun. (2002) 2716;
(g) D. Guo, B.G. Zhang, C.Y. Duan, X. Cao, Q.J. Meng, J. Chem. Soc., Dalton Trans.
(2003) 282;
[9] G.M. Sheldrick, SHELXL93, University of Göttingen, Germany, 1993.
[10] S.G. Baca, I.G. Filippova, C. Ambrus, M. Gdaniec, Y.A. Simonov, N. Gerbeleu, O.A.
Gherco, S. Decurtins, Eur. J. Inorg. Chem. 15 (2005) 3118.
[11] Z. Wang, H.H. Zhang, Y.P. Chen, C.C. Huang, R.Q. Sun, Y.N. Cao, X.H. Yu, J. Solid
State Chem. 179 (2006) 1536.
[12] F.A. Cotton, L.R. Fallvello, A.H. Reid, J.H. Tocher, J. Organomet. Chem. 319
(1987) 87.
[13] G. Li, Z.F. Li, H.W. Hou, X.R. Meng, Y.T. Fan, W.H. Chen, J. Mol. Struct. 694 (2004)
179.
(h) M. Kondo, R. Shinagawa, M. Miyazawa, M.K. Kabir, Y. Irie, T. Horiba, T.
Naito, K. Maeda, S. Utsuno, F. Uchida, Dalton Trans. (2003) 515.
[14] B.L. Wu, D.Q. Yuan, F.L. Jiang, L. Han, B.Y. Lou, C.P. Liu, M.C. Hong, Eur. J. Inorg.
Chem. 7 (2005) 1303.