The novel polymeric complex of manganese(II) with picolinic acid, [Mn(pic)2]n, a new coordination mode for picolinic acid

Article abstract of DOI:10.1002/zaac.200600064

A manganese(II) complex with novel coordination mode of picolinic acid (pic) has been synthesized and characterized by elemental analysis, magnetic susceptibility, FT-IR, thermal analysis (DTA and TG) and X-ray diffraction techniques. The complex crystallizes in the monoclinic space group P2 ₁/c with unit cell parameters: a = 10.4086 (6), b = 0.9524 (6), c = 10.3570 (6) A, β = 107.904 (4)° and Z = 4. In the complex all donor sites of picolinato ligands participated to the coordination. The ring nitrogen and one of the carboxylate oxygen atom of picolinato ligand form chelate ring with one Mn²⁺ ion, whereas the other carboxylate oxygen atom is coordinated to the other Mn²⁺ ion and forming a polymeric structure thermally stable up to 338 °C.

Full text of DOI:10.1002/zaac.200600064

DOI: 10.1002/zaac.200600064
The Novel Polymeric Complex of Manganese(II) with Picolinic Acid,
[
Mn(pic) ] , a New Coordination Mode for Picolinic Acid
2
n
a,
b
b
a
c
Zerrin Heren *, Hümeyra Pa s¸ ao gˇ lu , Gökhan Ka s¸ ta s¸ , Cem Keser , Orkan Zafer Ye s¸ ilel and
Orhan Büyükgüngörb
Kurupelit, Samsun / Turkey, Ondokuz Mayıs University, Faculty of Arts and Sciences, a Department of Chemistry and b Department of
Physics
c
Eski s¸ ehir / Turkey, Eski s¸ ehir Osmangazi University, Faculty of Arts and Sciences, Department of Chemistry
Received February 17th, 2006.
Abstract. A manganese(II) complex with novel coordination mode
of picolinic acid (pic) has been synthesized and characterized by
elemental analysis, magnetic susceptibility, FT-IR, thermal analysis
of the carboxylate oxygen atom of picolinato ligand form chelate
2
ϩ
ring with one Mn ion, whereas the other carboxylate oxygen
2
ϩ
atom is coordinated to the other Mn ion and forming a poly-
(DTA and TG) and X-ray diffraction techniques. The complex
meric structure thermally stable up to 338 °C.
crystallizes in the monoclinic space group P2
meters: a ϭ10.4086 (6), b ϭ 0.9524 (6), c ϭ10.3570 (6) A, β ϭ
1
/c with unit cell para-
˚
107.904 (4)° and Z ϭ 4. In the complex all donor sites of picolinato
Keywords: Manganese; Picolinic acid; Thermal analyses; Crystal
ligands participated to the coordination. The ring nitrogen and one
structures
1
Introduction
bonding mode (Scheme 2) as well as the mode in Scheme 1c
for picolinic acid was observed. In this structure, while the
picolinato ligand forms a chelate ring through N,O donors
by coordinating to one of the metal ions as bidentate, the
carboxylate group bridges to the other metal ion.
Picolinic acid (2-pyridinecarboxylic acid) has been a widely
investigated multidendate ligand and the general formula of
the metal picolinic acid complexes may be given as
[
M(C H NCOO) (H O)n] (nϭ 0, 2, 4) [1Ϫ9]. The picolin-
5 4 2 2
ate ligand within the crystal structures of these complexes
show several bonding modes (Scheme 1), from which the
N,O- chelating formed with the central metal ions and hy-
drogen bonding between the carboxylate group and water
molecules are dominant. Although picolinic acid has been
studied extensively, both structurally and spectroscopically
for many years [10Ϫ12], the polymeric complexes of this
ligand have not been synthesized up to now.
Scheme 2 New coordination mode for picolinate ligand.
In the present paper we report a novel crystalline coordi-
2
ϩ
nation polymer of Mn with picolinic acid, where a new
2
Results and Discussion
2.1 IR Spectrum
The most characteristic bands in the IR spectrum corre-
spond to the stretching vibrations of carbonyl group in the
expected regions [13]. It is often used here to correlate the
IR spectrum with the metal carboxylate structures by
using the difference between the asymmetric and symmetric
Scheme 1 Possible coordination modes for picolinate ligand.
Ϫ
Ϫ
carboxylate stretches (∆ ϭ νasym(COO ) Ϫ ν (COO ))
sym
Ϫ
[
14]. For the complex, [Mn(pic) ] , two ν
(COO ) values
*
Dr. Zerrin Heren
2 n
asym
Ϫ1
Department of Chemistry,
have been observed at 1675 and 1598 cm , and two
Ϫ
Ϫ1
Faculty of Arts and Sciences,
Ondokuz Mayis University
TRϪ55139, Kurupelit, Samsun / Turkey
Telephone:ϩ90 362 312 19 19
Fax: ϩ90 362 457 60 81
νsym(COO ) values at 1411 and 1345 cm . The corre-
sponding ∆ν values are 330 and 187 cm , confirming the
Ϫ1
monodentate and bidentate coordination modes, respec-
Ϫ
tively, of the (COO ) groups [14]. This conclusion is
EϪmail : zheren@omu.edu.tr
consistent with the X-ray diffraction measurements. The
1578
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Z. Anorg. Allg. Chem. 2006, 632, 1578Ϫ1581

The Novel Polymeric Complex of Manganese(II) with Picolinic Acid
Mn picolinato complex has a polymeric structure, where the
consists of Mn(pic) -monomer together with two picolinato
ligands (Fig. 2).
2
2
ϩ
two picolinate ligands coordinate to the Mn metal ion in
Ϫ
different manners. One of the (COO ) groups is in mono-
It should be underlined that the pic ligands adopt two
unusual coordination modes in the crystal structure. In the
first case, the carboxylate group (O1/C1/O2) is in a mono-
dentate mode, and bridges ion Mn1 to a neighboring ion
dentate form, while the second is in bidentate form and
2
ϩ
bridges two neighboring Mn ions. Apart from that the
Ϫ1
bands observed at 1653, 1631, 1576, 1477 and 1433 cm
ii
ii
might be attributed to the vibration modes of νasym and
Mn1 through carboxyl atom O2, with the Mn1···Mn1 dis-
Ϫ1
˚
νsym of CϭC/CϭN. The bands observed at 641 cm and
tance of 3.4908(5) A. In the second case, the carboxylate
Ϫ1
group (O3 C7 O4) is in a bidentate mode, and links Mn1i
4
43 cm can be assigned to the in- plane ring deformation
and out-of-plane deformation of the coordinated pyridine
ring, respectively [13]. These bands are observed to shift to
higher frequencies respect to its free ligand. The band
around 1000 cmϪ1 assigned to the ring breathing in the IR
spectrum of the free picolinic acid is appeared at 1015 cm
in the complex.
ion to the ion Mn1 through atom O3, and chelates ion
Mn1 through atom O4 and pyridine atom N2 (Fig. 3).
i
Atom O2 lies out of the plane of the pyridine ring by
˚
0.198 A in the opposite direction of Mn1 ion, as might be
Ϫ1
ii
expected from its bridging coordination to the Mn1 ion.
The Mn2 ion is six-coordinated by two N and four O
atoms from four pic ligands, yielding a distorted octahedral
environment (Fig. 3). The bond distances and angles are
ϩ
2.2 Magnetic susceptibility
given in Table 1. The MnϪO distances range from 2.1083
The solubility of this complex in a number of solvents such
as water, methanol, ethanol, acetone, DMF, DMSO was
found to be too low. Due to the very low solubility, it was
not possible to record UV-vis spectrum for the complex.
˚
(
12)Ϫ2.2212 (11) A, and are shorter than MnϪN distances.
This is similar to the situation reported for the related struc-
˚
tures [15Ϫ18]. The average CϪC (1.380 A) and CϪN
˚
(
1.336 A) distances in the pyridine ring are typical. The
Magnetic susceptibility value of the complex is µeff
ϭ
2ϩ
angles around the Mn ion are significantly distorted from
2
.27 BM. This low value may be explained by a strong in-
2
ϩ
terac tion between Mn ions in the polymeric structure.
2.3 Thermal analysis
Thermal analysis curves of the complex (DTA and TG) are
given in Figure 1. Thermal behavior of the complex was
followed up to 900 °C in a static atmosphere. The thermal
stability of the complex is very high. The polymeric com-
plex is thermally stable in air up to 338 °C and begins to
decompose without melting at 345 °C. In this consecutive
stage (DTA peaks at 400, 430, 450 °C), picolinato ligands
decompose and the organic residue burns. The final decom
position product black MnO was identified by IR spec-
2
troscopy (found 83.76; calc. 84.42 %).
Fig. 2 The perspective view and atom labelling scheme of
[
8 2 4 n
-C12H MnN O -] . Atomic displacement ellipsoids are drawn at
2.4 Crystallography
the 50 % probability level.
The crystal structure analysis indicates that the complex has
a polymeric two-dimensional network. The asymmetric unit
8 2 4 n
Fig. 3 Part of the crystal structure of [-C12H MnN O -] , showing
the formation of two-dimensional polymer chain. Symmetry codes:
Fig. 1 The TG and DTA curves of [Mn(pic)
2
]
n
.
(i) x, 3/2Ϫy, zϪ1/2; (ii) 1Ϫx, 1Ϫy, 2Ϫz; (iii) x, 3/2Ϫy, 1/2ϩz.
Z. Anorg. Allg. Chem. 2006, 1578Ϫ1581
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www.zaac.wiley-vch.de
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Z. Heren, H. Pa s¸ ao gˇ lu, G. Ka s¸ ta s¸ , C. Keser, O. Z. Ye s¸ ilel, O. Büyükgüngör
˚
3 Experimental Section
.1 Preparation of the complex [Mn(pic)2]n
Table 1 Selected bond lengths /A and bond angles /° for
MnN -]
[-C12
H
8
2 4 n
O
3
i
Mn1ϪN1
Mn1ϪO2
Mn1ϪO3
2.2699(14)
Mn1 ϪN2
Mn1 ϪO2
Mn1 ϪO4
Mn1ϪO4
C1ϪC2
C2ϪN1
C7ϪO3
2.2884(14)
2.1469(11)
2.2100(12)
2.2100(12)
1.516(2)
A solution of picolinic acid (8 mmol) in methanol was added drop
wisely upon stirring to a solution of [Mn(ac) ]·4H O (2 mmol) in
ii
2.2212(11)
2.1083(12)
2.1469(11)
2.2884(14)
1.219(2)
i
2
2
ii
iii
Mn1ϪO2
Mn1ϪN2
C1ϪO1
absolute ethanol. The solution was heated to 60 °C in a tempera-
ture-controlled bath and stirring for 5 h. The resulting solution was
left to slowly evaporate at r.t. Well-shaped light brown crystals, suit-
able for X-ray structure analysis, were collected after a week by
filtration, washed with water and acetone and finally dried in va-
iii
1.345(2)
C1ϪO2
1.280(2)
1.250(2)
N1ϪMn1ϪN2iii
O3ϪMn1ϪO2
115.36(5)
113.05(5)
160.15(5)
154.98(5)
145.56(5)
106.09(5)
73.91(5)
84.88(5)
134.97(12)
126.3(2)
O2 ϪMn1ϪN2
O4 ϪMn1ϪN2
O3ϪMn1ϪO2
O2 ϪMn1ϪO4
O3ϪMn1ϪN1
O3ϪMn1ϪN2
O4 ϪMn1ϪN1
O2ϪMn1ϪN1
O4ϪC7ϪO3
ii
iii
iii
97.58(5)
72.51(5)
96.89(5)
96.29(5)
92.47(5)
91.07(5)
84.93(5)
71.92(4)
126.4(2)
iii
cuo. C12
8 2 4
H MnN O (299.14); C 48.68 (calc. 48.13); H 2.46 (2.67);
iii
ii
O3ϪMn1ϪO4
N 9.82 (9.36) %.
iii
ii
iii
O2ϪMn1ϪN2
ii
O2 ϪMn1ϪN1
Ϫ
Ϫ
IR (KBr): υasym (COO ) 1675 vs, 1598 vs, υsym (COO ) 1411 vs,
1345 vs cmϪ1, υasym and υsym (CϭC/CϭN) 1653 s, 1631 vs, 1576 s,
ii
iii
Mn1 ϪO2ϪMn1
ii
iii
O2 ϪMn1ϪO2
Ϫ1
Ϫ1
Ϫ1
iii
1477 m, 1433 m cm , β(CϭN) 641 m cm , γ(CϭN) 443 m cm ,
O4 ϪMn1ϪO2
Ϫ1
C7ϪO3ϪMn1
O1ϪC1ϪO2
ring breath 1015 s cm .
3.2 Materials and measurements
All chemicals used were analytical reagent grade products. Manga-
nese(II) acetate tetrahydrate salt was obtained from Merck. Pico-
linic acid was purchased from ACROS organics.
octahedral configuration. This is mainly caused by the co-
ordination of the bridging O atom to another metal ion.
The bond angles of carboxylate groups are nearly equal
[
O1ϪC1ϪO2 ϭ 126.3(2)° and O4ϪC7ϪO3 ϭ 126.4(2)°].
Magnetic susceptibility measurement at room temperature was per-
formed using a Sherwood Scientific MXI model Gouy magnetic
balance. The IR spectrum was recorded in the 4000Ϫ400 cm re-
These values are greater than those observed in the related
structures [15, 16]. The angle between the planes through
the pic ligands is 36.13(5)°. The torsion angles of the
O1ϪC1ϪC2ϪN1 [174.8(2)°], O2ϪC1ϪC2ϪC3 [170.9(2)°],
O3ϪC7ϪC8ϪN2 [177.3(2)°] and O4ϪC7ϪC8ϪC9
Ϫ1
gion with a Mattson 1000 FTϪIR spectrometer using KBr pellets.
TG8110 thermal analyzer was used to record simultaneous TG and
Ϫ1
DTA curves in static air atmosphere at a heating rate of 10 Kmin
in the temperature range 20Ϫ1000 °C using platinum crucibles.
[
178.3(2)°] suggest that the pic groups are nearly planar.
2 3
Highly sintered αϪAl O was used as a reference and the DTG
The chelate ring (Mn1ϪO2ϪC1ϪC2ϪN1) is close to
Ϫ1
sensitivity was 0.05 mgs . The elemental analysis was carried out
˚
planar, with an r.m.s deviation of 0.1057 A. In this chelate
ring, the bridging O2 atom has a maximum deviation
˙
at the TÜBITAK Marmara Research Centre.
˚
[
0.146(9) A].
The packing of Mn(pic) moieties in the crystal structure
2
3
.3 Crystallographic analysis
is shown in Figure 4. The polymer chains extend through
the bc plane. It is interesting to see that the dinuclear
Mn (µ-O) moiety has different directions in the crystal
Diffraction experiments were carried out at 296 K on a Stoe IPDS
diffractometer. The structure was solved by direct methods and re-
fined using the programs SHELXS97 and SHELXL97 [19]. All
non-hydrogen atoms were refined anisotropically by full-matrix le-
ast-squares methods [SHELXL-97]. The hydrogen atoms were
placed in geometrically idealized positions and refined as riding
atoms. The relevant crystal data and experimental conditions along
with the final parameters are summarized in Table 2. Data collec-
tion: X-Area, cell refinement: X-Area, data reduction: X-RED [20];
program(s) used for molecular graphics: ORTEP-3 for Windows
2
2
structure, that is, there are two bridges which are approxi-
mately perpendicular to each other.
[
[
21]; software used to prepare material for publication: WinGX
22].
Supplementary Material: Crystallographic data for the structural
analysis have been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 295003. Copies of this information may
be obtained free of charge from the Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (fax: ϩ44-1223-336033; e-mail:
deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
Acknowledgements. We wish to acknowledge the Faculty of Arts
and Sciences, Ondokuz Mayıs University, Turkey, for the use of the
STOE IPDS-II diffractometer (purchased under grant F.279 of the
University Research Fund).
Fig. 4 The unit-cell packing of the complex, [-C12
parallel to bc plane.
8 2 4 n
H MnN O -] ,
1580
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 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2006, 1578Ϫ1581

The Novel Polymeric Complex of Manganese(II) with Picolinic Acid
[
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2
8 2 4 n
[-C12H MnN O -]
[
Empirical formula
Formula weight
Temperature /K
Wavelength /A
Crystal system
Space group
C
299.14
296
0.71073 MoK
monoclinic
P2
12
H
8
MnN
2
O
4
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[
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α
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/c
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˚
a, b, c /A
10.4086 (6); 10.9524 (6); 10.3570 (6)
353, 8, 129.
β /°
107.904 (4)
1123.51 (11)
4
1.186
1.769
0.35 ϫ 0.27 ϫ 0.13
2.1Ϫ26.0
15886
2213
Integration
˚
3
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Absorption coefficient /mm
[
[
12] S. Basu, S.-M. Peng, G.-H. Lee, S. Bhattacharyya, Polyhedron
005, 24,157.
Ϫ3
Dcalc /Mg m
2
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Theta range for data collection (deg)
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2
Full-matrix least-squares on F
2
2
Final R indices [F >2σ(F )]
R indices (all data)
R
R
1
ϭ 0.024, wR
ϭ0.028, wR
2
ϭ 0.066
ϭ 0.067
1
2
Goodness-of-fit on F2
1.060
[
[
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Z. Anorg. Allg. Chem. 2006, 1578Ϫ1581
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1581