Versatility of pyridine-2-methanol as a chelating ligand toward a manganese ion: Synthesis and X-ray structural analysis on some manganese-pyridine-2-methanol derivatives

Article abstract of DOI:10.1016/j.ica.2003.09.028

A systematic synthesis and X-ray structural analysis have been made for several manganese derivatives with pyridine-2-methanol as a chelating ligand; neutral Mn(C₅NH₄-2-CH₂OH)₂(C ₆F₅CO₂)₂ (1), trans-[Mn(C ₅H₄N-2-CH₂-OH)₂{C₆F ₄-1,4-(CO₂)₂}]_∞ (2), cis-[Mn(C₅H₄N-2-CH₂-OH)₂{C ₆F₄-1,3-(CO₂)₂}]_∞ (3), {Mn(C₅H₄N-2-CH₂-OH)₂(4, 4′-bipyridine)(ClO₄)}_∞ (4), and Mn(C ₅H₄N-2-CH₂-OH)₃(ClO ₄)₂(4,4-azopiridine) (pyridine-2-methanol) (5) are our results. 1 and 5 are monomers, while 2-4 are polymers. An oxidation state of the manganese ion in 1, 2, 3, and 5 is 2⁺, while that of 4 is suggested to be 3⁺. The magnetic data of 4 down to 2 K are measured. The length of the linker ligand has been suggested to afford a crucial effect on the dimensionality of the product.

Full text of DOI:10.1016/j.ica.2003.09.028

Inorganica Chimica Acta 357 (2004) 1039–1046
www.elsevier.com/locate/ica
Versatility of pyridine-2-methanol as a chelating ligand toward
a manganese ion: synthesis and X-ray structural analysis on
some manganese-pyridine-2-methanol derivatives
*
Mitsuhiro Ito, Satoru Onaka
Department of Environmental Technology, Graduate School of Engineering, Nagoya Institute of Technology,
Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
Received 5 June 2003; accepted 16 September 2003
Abstract
A systematic synthesis and X-ray structural analysis have been made for several manganese derivatives with pyridine-2-methanol
as a chelating ligand; neutral Mn(C5NH4-2-CH2OH)2(C6F5CO2)2 (1), trans-[Mn(C5H4N-2-CH2-OH)2{C6F4-1,4-(CO2)2}]1 (2), cis-
[Mn(C5H4N-2-CH2-OH)2{C6F4-1,3-(CO2)2}]1 (3), {Mn(C5H4N-2-CH2-OH)2(4,40-bipyridine)(ClO4)}1 (4), and Mn(C5H4N-2-
CH2-OH)3(ClO4)2(4,4-azopiridine) (pyridine-2-methanol) (5) are our results. 1 and 5 are monomers, while 2–4 are polymers. An
oxidation state of the manganese ion in 1, 2, 3, and 5 is 2þ, while that of 4 is suggested to be 3þ. The magnetic data of 4 down to 2 K
are measured. The length of the linker ligand has been suggested to afford a crucial effect on the dimensionality of the product.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Pyridine-2-methanol; Coordination polymers; X-ray analyses; Anti-ferromagnetic interactions
1. Introduction
gether with pentafluorobenzoic acid to the solution
which contains manganese(II) perchlorate ion in order
to examine a substituent effect of the CH2-OH group
on the monomer structure and/or the supra structure of
the resulting manganese complex. Single crystal X-ray
structure analysis for the product has shown that the
pyridine-2-methanol functions as a chelating ligand and
Pyridine derivatives with an ortho-substituent
(C5H4N–X, Chart 1; X ¼ CH3, NH2, CO2H, OR, OH,
CHO, SH and so on) are ubiquitous and yet very
versatile ligands. Thus plethora of metal derivatives
with them have been reported [1]. Pyridine derivatives
with two ortho-substituents (C5H3N–Y2, Chart 2) have
recently been revived as an important supporting li-
gands of multiple metal–metal bonds and/or linear
metal–metal bonded arrays which are composed by
more than three metal atoms [2–11]. We have suspected
in the course of our attempt to construct new supra
structures based on manganese ions why pyridine-2-
methanol has not yet been well explored as a potential
supporting ligand of such an array and/or as a simple
dangling or chelating ligand to the best of our knowl-
edge [12–14]. Therefore, we added pyridine-2-methanol
at first as a simple monodentate pyridine ligand to-
Chart 1.
* Corresponding author. Fax: +81-52-735-5160.
E-mail address: onklustr@ks.kyy.nitech.ac.jp (S. Onaka).
Chart 2.
0020-1693/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2003.09.028

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M. Ito, S. Onaka / Inorganica Chimica Acta 357 (2004) 1039–1046
the neutral Mn(C5NH4-2-CH2OH)2(C6F5CO2)2 mono-
mer complex is formed in contrast to the findings by
Hendrickson et al. [12–14]; they have obtained Mn4
clusters instead by reacting this ligand with MnX2. The
present paper reports on our systematic synthesis and
single crystal X-ray analyses of pyridine-2-methanol
derivatives with manganese ions which are entailed by
other ligands.
2.4. Synthesis of cis-[Mn(C5H4N-2-CH2-OH)2{C6F4-1,
3-(CO2)2}] (3)
1
Similar synthetic procedure as 2 was employed. From
127 mg of Mn(ClO4)2 ꢀ 6H2O, colorless crystals 3 were
obtained in 51% yield. Anal. Calc. for C20H14F4
MnN2O6: C, 47.16; H, 2.77; N, 5.50. Found: C, 47.17;
H, 2.89; N, 5.54%.
2.5. Synthesis of [cis-{Mn(C5H4N-2-CH2-OH)2(4,40-
bipyridine)(ClO4)} (4)
1
2. Experimental
To an absolute ethanol solution (10 ml) which con-
tained 76 mg (0.7 mmol) of 2-pyridinemethanol and 55
mg (0.35 mmol) of 4,40-bipyridine, solid Mn(ClO4)2 ꢀ
6H2O (127 mg, 0.35 mmol) was added by portions at
one time with stirring and the stirring was continued for
5 h at room temperature. Then a dark purple solution
was extracted with a large quantity of water. After fil-
tration, the solvent was evaporated by standing at room
temperature for several days to afford purple crystals in
41% yield. Anal. Calc. for C22H22ClMnN4O6: C, 49.96;
H, 4.19; N, 10.60. Found: C, 49.56; H, 3.85; N, 10.69%.
2.1. Materials and general procedures
Syntheses and manipulations were generally made
under an open air unless otherwise described. Pyridine-
2-methanol was purchased from Tokyo Kasei Kogyo
Co., Ltd. Colorless liquid is requisite to the synthesis;
results are not reproducible if colored pyridine-2-meth-
anol is used. 4,40-azopyridine was synthesized by litera-
ture method [15]. Other chemicals and solvents were
purchased from Wako Pure Chemical Ind., Ltd. or Al-
drich. Caution! Organic perchlorate salts are potentially
explosive. All perchlorates salts should be handled with
care.
2.6. Synthesis of mer-trans-[Mn(C5H4N-2-CH2-OH)3]-
(ClO4)2ꢀ(4,4-azopiridine)ꢀ(pyridine-2-methanol) (5)
2.2. Synthesis
(C6F5CO2)2 (1)
of
trans-Mn(C5H4N-2-CH2-OH)
129 mg (0.7 mmol) of azopyridine and 76 mg of 2-
pyridinemethanol (0.7 mmol) were dissolved in 10 ml of
absolute ethanol. Solid Mn(ClO4)2 ꢀ 6H2O (760 mg, 2.1
mmol) was added to this solution by portions at one
time and the mixture was stirred at ambient temperature
for 5 h. The resulting orange solution was filtered and
the filtrate was left in a refrigerator for a month to afford
orange crystals. Yield 37% based on the manganese salt.
Anal. Calc. for C34H35Cl2MnN8O12: C, 46.85; H, 3.93;
N, 12.84. Found: C, 46.22; H, 4.11; N, 12.75%.
76 mg (0.7 mmol) of 2-pyridinemethanol and 148 mg
(0.7 mmol) of pentafluolobenzoic acid was dissolved in
10 ml of absolute ethanol. To this was added solid
Mn(ClO4)2 ꢀ 6H2O (507 mg, 1.4 mmol) with a small
portion at one time and the mixture was stirred at room
temperature for 5 h. The resulting colorless solution was
filtered and the filtrate was left standing at room tem-
perature for a week to afford colorless single crystals.
Yield 75% based on the manganese salt. Anal. Calc. for
C26H14F10MnN2O6: C, 44.91; H, 2.03; N, 4.03. Found:
C, 44.88; H, 2.01; N, 4.05%.
2.7. Single crystal X-ray analysis on 1–5
Suitable crystals of these five compounds were ob-
tained from recrystallization processes described above.
The selected crystals were glued to the top of a fine glass
rod. Accurate cell dimensions were determined by least-
square refinements of 20–25 reflections on a MAC
MXC3 diffractometer equipped with a graphite-mono-
2.3. Synthesis of trans-[Mn(C5H4N-2-CH2-OH)2{C6F4-
1,4- (CO2)2}] (2)
1
76 mg (0.7 mmol) of 2-pyridinemethanol and 83 mg
(0.35mmol) of tetrafluorophthalic acid were dissolved in
10 ml of absolute ethanol. To this was added solid
Mn(ClO4)2 ꢀ 6H2O (127 mg, 0.35 mmol) with a small
portion at one time and the mixture was stirred at room
temperature for 5 h. The resulting colorless mixture was
left standing in a refrigerator for a week to afford col-
orless crystals. Yield 88%. Anal. Calc. for C20H14-
F4MnN2O6: C, 47.16; H, 2.77; N, 5.50. Found: C, 47.11;
H, 2.88; N, 5.56%.
ꢀ
chromated Mo Ka radiation (k ¼ 0:71073 A). The re-
flection data were collected at r.t. Complete crystal data
are collated in Table 1. The structures were solved by the
direct method, SIR97 for 1, 2, 4, and 5 and SIR92 in a
CRYSTAN-GM program package for 3. The structures
were refined by full-matrix least-squares with aniso-
tropic thermal parameters for all non-hydrogen atoms
using SHELXS97 on F 2 except 3, to which aforemen-
tioned CRYSTAN-GM program package was applied

M. Ito, S. Onaka / Inorganica Chimica Acta 357 (2004) 1039–1046
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Table 1
Crystal data
Compound
1
2
3
4
5
Empirical formula
Formula weight
Crystal system
Space group
C
695.3
26H14F10MnN2O6
C16H14F4MnN2O4
509.3
C16H14F4MnN2O4
509.3
C22H22ClMnN4O6
528.8
C34H35Cl2MnN8O12
873.5
triclinic
monoclinic
P21=a
16.720(4)
6.015(1)
13.390(3)
monoclinic
P21=n
17.25(1)
monoclinic
P21=n
15.688(6)
tetragonal
P4=ncc
24.775(9)
24.775(9)
15.024(7)
ꢁ
P1
ꢀ
a (A)
11.519(4)
18.678(6)
19.381(6)
81.91(3)
74.82(3)
74.70(3)
4
ꢀ
b (A)
9.526(6)
5.933(4)
9.066(3)
14.996(4)
ꢀ
c (A)
a (°)
b (°)
c (°)
Z
104.71(2)
94.89(5)
111.62(3)
2
1.76
2
1.73
4
1.70
16
1.80
Dcalc (g cmꢁ3
)
1.50
0.6 ꢂ 0.4 ꢂ 0.4
Crystal dimensions
(mm3)
0.5 ꢂ 0.5 ꢂ 0.3
0.4 ꢂ 0.2 ꢂ 0.2
0.50 ꢂ 0.40 ꢂ 0.30
0.2 ꢂ 0.1 ꢂ 0.1
3
ꢀ
V (A )
1302.4(6)
5.37
971.7(4)
8.03
1983(1)
7.82
9221(7)
7.83
3870(4)
5.73
l(Mo Ka) (cmꢁ1
Scan type
Scan range
)
2h ꢁ x
1:70 þ 0:35 tan h
6.0
2h ꢁ x
1:10 þ 0:35 tan h
6.0
2h ꢁ x
1:15 þ 0:35 tan h
6.0
2h ꢁ x
2h ꢁ x
1:25 þ 0:35 tan h
6.0
1:25 þ 0:3535 tan h
Scan speed (deg minꢁ1
)
6.0
2hmax (°)
50.0
298
55.0
298
55.0
298
45.0
298
3020
45.0
298
Temperature (K)
Unique reflections
Reflections with
jFoj > 3rðjFojÞ
2290
2239
4573
10113
1821
222
926
152
1777
304
1091
253
4511
1028
Number of parameters
Refined
R
Rw
0.054
0.158
0.087
0.232
0.091
0.089
0.12
0.24
0.09
0.23
P
P
P
2
2 1=2
Mo Ka radiation (k ¼ 0:71073 A); R ¼ kFok ꢁ jFck=jFoj; Rw ¼ ½ ðjFoj ꢁ FcjÞ = wðFoÞ ꢃ where w ¼ 1=r2ðF Þ.
ꢀ
1
manganese ion [16,17]. Fig. 1 also shows that two
on F . The positions of H atoms were assigned with
common isotropic displacement factors and were refined
by use of geometrical restraints in the final refinement
cycle. The final R and Rw values are also listed in Table
1. Tables for atomic coordinates, thermal parameters,
and bond lengths and angles are available as supple-
mentary material. Selected bond lengths and angles are
given in Table 2.
ꢁ
C6F5CO2 anions coordinate to one Mn(II) ion as a
monodentate terminal ligand. Thus, a mononuclear
trans geometry is formed for this combination of ligands.
The IR spectrum of 1 exhibits a lower-energy shifted
broad band due to the OH stretching (from 3260 to 3170
cmꢁ1). Similar lower energy shifts were observed for 2, 3,
and 5. The Fourier synthesis at the final stage of the least-
squares refinement for X-ray analysis has successfully
located the position of the H atom of the OH group in
pyridine-2-methanol. The finding indicates that pyridine-
2-methanol functions as a neutral ligand. The oxidation
state of the manganese ion is thus estimated to be 2þ. The
molecular and crystal structure analyses on 2 (Figs. 2 and
3) have shown that the tetrafluoroterephthalate ligand
bridges two manganese ions with a trans geometry via
one terminal oxygen in each carboxylate group to afford
one-dimensional infinite chains (Fig. 3). The formal ox-
idation state of the manganese ion is estimated to be 2þ.
When 2, 4, 5, 6-tetrafluoro-isophthalate is employed in-
stead, a cis-isomer 3 is obtained (Fig. 4). The crystal
packing diagram (Fig. 5) shows that 3 forms a quasi-one-
dimensional infinite chain in almost the ac-plane; one O
2.8. Spectroscopies and magnetic measurements
IR spectra were measured by use of a JASCO Her-
schel 460+ for KBr samples. Magnetic data were mea-
sured by use of a SQUID magnetometer (a Quantum
Design MPMS-5P) between 2 and 300 K. The fit and the
analysis of the data were made by use of the computer
software Kaleida-Graph 3.52.
3. Results and discussion
3.1. Molecular and crystal structures
ꢁ
The whole scheme of the synthesis is summarized in
Scheme 1. The molecular structure analysis on 1 (Fig. 1)
has clearly revealed for the first time that the pyridine-2-
methanol can function as a chelating ligand for a single
atom in each CO2 group coordinates to a Mn ion as a
1
Some chelating examples on similar 2, 6-substituted pyridine di-
methanol ligand were reported previously for Mo and Re.

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M. Ito, S. Onaka / Inorganica Chimica Acta 357 (2004) 1039–1046
Table 2
ꢀ
Selected bond-lengths (A) and angles (°)
Compound
Mn–N(py)
1
2
3
4
5 mol ꢀ 1
mol ꢀ 2
2.242(3)
2.59(3)
2.233(1)
2.200(1)
2.1293(9)
2.281(8)
2.284(9)
2.109(2)
2.168(2)
2.207(2)
2.230(2)
2.228(1)
2.227(1)
2.183(1)
2.1809(9)
2.181(2)
2.197(2)
2.231(1)
2.2432(9)
2.185(1)
2.198(1)
Mn–O(py)
2.198(7)
2.219(6)
1.888(2)
1.782(2)
Mn–O(CO2)
2.152(3)
2.095(7)
2.151(6)
Mn–N(bipy)
2.188(2)
O(py)–Mn–O(CO2)
90.2(1)
89.8(1)
91.63(2)
88.37(2)
84.3(3)
87.2(2)
90.2(2)
175.9(2)
72.0(3)
72.1(3)
159.6(3)
90.0(2)
O(py)–Mn–N(py)
89.0(1)
91.0(1)
73.32(1)
106.68(1)
80.0(9)
95.6(9)
90.1(9)
94.2(9)
N(py)–Mn–O(CO2)
74.0(1)
106.0(1)
85.24(2)
94.76(2)
180.00
N(py)–Mn–N(py)
O(py)–Mn–O(py)
O(CO2)–Mn–O(CO2)
N(py)–Mn–N(bipy)
180.00(2)
180.00(2)
180.00
180.00
93.2(2)
91.0(2)
175.5(9)
89.4(9)
93.9(8)
87.1(8)
91.8(9)
98.6(9)
93.4(9)
80.0(9)
88.1(8)
167.9(9)
O(py)–Mn–N(bipy)
N(bipy)–Mn–N(bipy)
Scheme 1.
monodentate ligand. Fig. 6 shows the molecular struc-
ture of 4, which has a similar cis-geometry to that of 3.
Two 4,4-bipyridine ligands coordinate to one manganese
ion in a cis-disposition. An infinite Z-shaped chain thus
constructed is shown in Fig. 7. This one-dimensional-
zigzag chain is quite similar to that of [Mn(hfac)2(4,40-
bipy)]n which was recently reported by Liao et al. [18].
However, two pyridyl rings are somewhat twisted in
contrast to that of the hfac derivative. One perchlorate
ion is situated in a close proximity to one manganese ion.
As is described below, the metric parameters on Mn–O
distances of 4 are quite short compared with those of 1–3,
and 5, suggesting that the pyridine-2-methanol functions
as an anion in 4. These suggest that the manganese ion is

M. Ito, S. Onaka / Inorganica Chimica Acta 357 (2004) 1039–1046
1043
Fig. 1. The ORTEP drawing of trans-Mn(C5H4N-2-CH2-OH)
(C6F5CO2)2 (1).
Fig. 4. The ORTEP drawing of cis-[Mn(C5H4N-2-CH2-OH)2{C6F4-
1,3-(CO2)2}]1 (3).
Fig. 2. The ORTEP drawing of trans-[Mn(C5H4N-2-CH2-OH)2
{C6F4-1,4-(CO2)2}]1 (2).
Fig. 5. The crystal packing diagram of 3 showing a quasi one-dimen-
sional infinite chain. The view almost along the b axis.
Fig. 3. Infinite Z-shaped chain structures of 2. The view almost along
the a axis.
which indicates that the crystal is composed of a racemic
mixture of two chiral isomers. The crystal contains each
one free 2-pyridine methanol and 4,40-azobipyridine
molecules (Fig. 9) in addition to two perchlorate ions for
each manganese ion;azo N2 positions of one solvate 4,40-
azobipyridine are disordered. Perhaps these two ligands
are held by hydrogen bonds to perchlorate ions. The
formal oxidation state of the manganese ion is presumed
to be 2þ. From the comparison of molecular structures
for 1–4, it has been shown that the geometry of bis(2-
pyridinemethanol) manganese derivatives depends on
the coexisting ligand together with the mutual position-
ing of two sets of N and O coordinating atoms in bis(2-
pyridinemethanol) ligands; two N atoms and two O
atoms are located in trans positions for 1 and 2, while this
in the 3þ oxidation state. The crystal packing diagram in
Fig. 7 demonstrates also that the perchlorate ion is close
to hydrogen atoms of 4,4-bipyridine ligands, indicating
possible hydrogen bonds among the oxygen atoms in
perchlorate ions and the hydrogens of 4,4-bipyridines;
the perchlorate ion is located in the center of channels
which are composed of the manganese ions and 4,40-bpy.
When trans-4,40-azobipyridine, which has a bent skele-
ton but is expected to be functionally similar to 4,40-bi-
pyridine, is reacted with Mn(ClO4)2 ꢀ 4H2O and 2-
pyridinemethanol in absolute ethanol, no such polymer
as 4 has yet been obtained. Instead, tris(2-pyridine
methanol) manganese perchlorate 5 is obtained (Fig. 8).
Two independent molecules are contained in the crystal,

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M. Ito, S. Onaka / Inorganica Chimica Acta 357 (2004) 1039–1046
Fig. 6. The ORTEP drawing of [cis-{Mn(C5H4N-2-CH2-OH)2(4,40-
bipyridine)(ClO4)}1(4).
Fig. 9. The crystal packing diagram of 5, which indicates solvate
molecules. The view is almost along the a axis.
trans preference is not kept in 3 and 4 which have cis-
geometries. However, the octahedral skeleton for 3 is
severely distorted from the ideal one. For tris-chelated
compound 5, trans dispositions are seen for each one set
of N–N and O–O combinations and one set of N–O
combination. Similar severe distortion from the ideal
octahedral geometry as 3 is observed for 5. These dis-
tortions are reflected clearly on the bond-angle parame-
ters as shown in Table 2. Details on these bonding
parameters are discussed below.
Fig. 7. An infinite Z-shaped chain constructed from 4.
3.2. Molecular parameters
From the molecular parameters listed in Table 2,
following trends have been clarified. Mn–pyridine N
ꢀ
bond distances are in the range 2.109–2.284 A, which is
close to normal Mn–pyridine N distances [16,17]. Mn–O
(pyridine–methanol) distances are in the range 1.782–
ꢀ
2.243 A, while Mn–O (carboxylate) distances are in the
ꢀ
range 2.095–2.152 A. For 1–3, each carboxylate group
acts as a monodentate ligand via one O atom. Thus Mn–
O distances for these complexes are longer than those in
which carboxylate groups act as a bidentate chelating
ligand [18]. Mn–pyridine N and Mn–O (pyridine–meth-
anol) distances are found very short for 4 (2.109 (2) and
ꢀ
ꢀ
2.168 (2) A for Mn–N and 1.782 (2) and 1.888 (2) A for
Mn–O, respectively), compared with those of 1–3 and 5;
the finding is best accounted for in terms of the anion
formation of NC5H4–CH2Oꢁ and the coordination to
the manganese ion via Oꢁ as described above. The
Fig. 8. The ORTEP drawing of mer-trans-Mn(C5H4N-2-
CH2-OH)3(ClO4)2(4,4-azopiridine)(pyridine-2-methanol) (5) for one
molecule.
ꢀ
Mn–N (bipy) distance in 4 is 2.188(2) A, which is close to
those found for other Mn-4,40-bipy complexes [19], but is

M. Ito, S. Onaka / Inorganica Chimica Acta 357 (2004) 1039–1046
1045
significantly shorter than that of [Mn(hfac)2(4,4-bipy)]n
Mn(III) (S ¼ 2) and gMn ¼ 2.00. This value decreases
slowly 300 K until from 19 K and abruptly decreases to
2.98 cm3 K/mol below this temperature, which is typical
for an anti-ferromagnetically interacting system. The
magnetic data for 4 are in agreement with the assign-
ment of the 3þ oxidation state to the manganese ion.
ꢀ
(2.257(5) A) [15]. The crystal of 5 is composed from ra-
cemic mixtures as described above. Mn–N distances of
ꢀ
molecule 1 (2.181–2.231 A, average 2.203 A) are slightly
ꢀ
ꢀ
shorter than those of molecule 2 (2.207–2.230 A, average
ꢀ
2.222 A), while Mn–O distances of the former molecule
ꢀ
(2.185–2.243 A, average 2.221 A) are only slightly longer
ꢀ
ꢀ
than those of the latter molecule (2.181–2.227 A, average
ꢀ
2.197 A).
3.4. Polymer formation
Distortions from ideal octahedral geometry for 3 and
5 are evaluated from the bond angles around the rele-
vant manganese ion. O3–Mn–N2 angle is 159.6(3)°, O1–
Mn–N1 is 156.0(3), N1–Mn–O3 is 72.0(3)° for 3. These
angles are far from the ideal linear and right angles.
Similar deviations are observed for 5; N–Mn–N an-
gles are 151.0(5), 109.1(4)°, and 97.7(5)°, O–Mn–O an-
gles are 105.5(5)°, 161.6(4)°, 108.8(4)°, 156.0(4), 88.7(5)°,
and 87.0(5)°, and N–Mn–O angles are in the range
72.6(5)°)105.6(5)° and 157.0(5)°)157.9(5)°. Bond angles
around respective manganese ions for 1, 2, and 4 are
quite close to 180° and/or 90° (Table 2).
Four kinds of bidentate ligands have been examined
to investigate the influence of these ligands on the
structure and/or dimensionality of coordination poly-
mers in addition to pyridine–methanol. An interesting
ꢁ
observation is that the positions of CO2 groups in
2ꢁ
C6F4(CO2)2 do not afford dramatic change on the
gross polymer structures of 2 and 3 in spite of having
different geometries around the corner manganese ions
for these complexes. The use of 4,40-bipyridine as a
linker affords significant change on the polymer struc-
ture 4 as was described in the molecular and crystal
structure section. However, 4,40-azopyridine, of which
function is expected to be likely to that of 4,40-bipyri-
dine, is contained as only a solvate molecule in the
crystal in addition to one 2-pyridinemethanol solvate
molecule. Both molecules are held via hydrogen bonds
with perchlorate ions in the crystal of 5. The lengths of
these four bifunctional linkers are significantly different.
In this context it is quite interest to refer to the paper by
Cotton and his group [20] in which they have suggested
that the length of the linker determines the type and the
structure of the polymer formed and the dimensionality
of the polymer is reduced from two to one if a longer
linker is used. It is worthwhile to point out the relevance
of their suggestion to our finding that 4,4-azopyridine,
which is the longest linker employed in this study, does
not afford polymer.
3.3. Magnetic data
Oxidation states estimated above are based on the
assumption that 2-pyridinemethanol is a neutral ligand;
the oxidation states of manganese ion for 4 was deduced
from the Mn–O bond distances at first and later by
magnetic susceptibility measurements. The precise
magnetic behavior of 4 for the temperature range 10–
300 K is shown in Fig. 10 in the forms of vm vs. T and
vmꢁ1 T vs. T plots. The vmT value at room temperature is
3.65 cm3 K/mol, which is slightly lower than that of the
non-interacting spin-only value of 3.77 cm3 K/mol for
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
120
100
80
60
40
20
0
Acknowledgements
This research was financially supported by Grants-in-
aid for Science research on Priority Areas (No.
12023221 ÔMetal-assembled ComplexesÕ) and by Grants-
in-aid for Science research No. 14540514 from the
Ministry of Education, Science, Sports, and Culture,
Japan.
References
[1] F.A. Cotton, G. Wilkinson, C.A. Murillo, M. Bochmann,
Advanced Inorg. Chem., sixth ed., some examples are shown in
this textbook.
0
50
100
150
200
250
300
Temperature / K
[2] S.-J. Shieh, C.-C. Chou, G.-H. Lee, C.-C. Wnag, S.-M. Peng,
Angew. Chem. Int. Ed. 36 (1997) 56.
Fig. 10. Plots of molar susceptibility vm vs temperature for compound
4. The solid line represents a least-squares fit of the data to the theo-
retical equation by Hiller et al. [21].
[3] A.R. Charkravarty, F.A. Cotton, D.A. Tocher, Inorg. Chem. 24
(1985) 1263.

1046
M. Ito, S. Onaka / Inorganica Chimica Acta 357 (2004) 1039–1046
[4] F.A. Cotton, L.D. Gage, Inorg. Chem. 18 (1979) 1716.
[5] F.A. Cotton, R.H. Niswander, J.C. Sekutowski, Inorg. Chem. 18
(1979) 1152.
[13] J. Yoo, E.K. Brechin, A. Yamaguchi, M. Nakano, J.C. Huffman,
A.L. Maniero, L.-C. Brunel, K. Agawa, H. Ishimoto, G. Christou,
D.N. Hendrickson, Inorg. Chem. 39 (2000) 3615.
[6] F.A. Cotton, R.H. Niswander, J.C. Sekutowski, Inorg. Chem. 17
(1978) 3541.
[14] J. Yoo, A. Yamaguchi, M. Nakano, J. Krzystek, W.E. Streib, L.-
C. Brunel, H. Ishimoto, G. Christou, D.N. Hendrickson, Inorg.
Chem. 40 (2001) 4604.
[7] F.A. Cotton, R.H. Niswander, J.C. Sekutowski, Inorg. Chem. 18
(1979) 1149.
[15] E.B. Brown, R. Granneman, J. Am. Chem. Soc. 97 (1975) 621.
[16] J.M. Berg, R.H. Holm, Inorg. Chem. 22 (1983) 1768.
[17] T.I.A. Gerber, J. Bruwer, G. Bandoli, J. Perils, J.G.H. du Preez, J.
Chem. Soc., Dalton Trans. (1995) 2189.
[8] B.E. Bursten, F.A. Cotton, A.H. Cowley, B.E. Hanson, M.
Lattman, G.G. Stanley, J. Am. Chem. Soc. 101 (1979) 6224.
[9] A.R. Chakravarty, F.A. Cotton, E.S. Sharmshoum, Inorg. Chem.
23 (1984) 4216.
[18] H.-Y. Shen, D.-Z. Liao, Z.-H. Jiang, S.-P. Yan, B.-W. Sun, G.-L.
Wang, X.-K. Yao, H.-G. Wang, Polyhed. 17 (1998) 1953.
[19] C.H. Weng, Ph.D. Dissertation, Carngier-Mellon University,
Pittsburgh, PA, 1968.
[10] F.A. Cotton, W.H. Ilsley, W. Kaim, Inorg. Chem. 18 (1979)
3569.
[11] F.A. Cotton, W.H. Ilsley, W. Kaim, Inorg. Chem. 19 (1980)
1453.
[20] F.A. Cotton, C. Lin, C.A. Murillo, Inorg. Chem. 40 (2001) 5886.
[21] W. Hiller, J. Strahle, A. Dtaz, M. Hanack, W.E. Hatfield, L.W.
ter Haar, P. Gutlich, J. Am. Chem. Soc. 106 (1984) 329.
[12] E.K. Brechin, J. Yoo, M. Nakano, J.C. Huffman, D.N. Hend-
rickson, G. Christou, J. Chem. Soc. Chem. Commun. (1999) 783.