Pyridine-type complexes of transition-metal halides. Part XV. Mn(II) chloride complexes with 3,4- and 3,5-lutidine

Article abstract of DOI:10.1023/B:JTAN.0000027190.32572.8b

Manganese(II) chloride complexes with 3,4- and 3,5-lutidine have been prepared. The crystal symmetry and cell dimensions have been calculated on the basis of powder diffraction data. The compounds were characterised also by FT-IR spectrometry. The thermal

Full text of DOI:10.1023/B:JTAN.0000027190.32572.8b

Journal of Thermal Analysis and Calorimetry, Vol. 75 (2004) 965–974
PYRIDINE-TYPE COMPLEXES OF
TRANSITION-METAL HALIDES
Part XV. Mn(II) chloride complexes with 3,4- and
3,5-lutidine
K. Mészáros Szécsényi1*, T. Wadsten2, A. Kovács3 and G. Liptay2
1Department of Chemistry, Faculty of Sciences, University of Novi Sad, 21000 Novi Sad,
Trg D. Obradoviºa 3, Serbia Montenegro
2Department of Inorganic Chemistry, Budapest University of Technology and Economics,
1521 Budapest, Hungary
3Research Group of Technical Analytical Chemistry of the Hungarian Academy of Sciences at the
Institute of General and Analytical Chemistry, Budapest University of Technology and
Economics, 1521 Budapest, Hungary
(Received May 30, 2003; in revised form December 17, 2003)
Abstract
Manganese(II) chloride complexes with 3,4- and 3,5-lutidine have been prepared. The crystal
symmetry and cell dimensions have been calculated on the basis of powder diffraction data. The
compounds were characterised also by FT-IR spectrometry. The thermal decomposition of the
complexes has been studied by thermogravimetry and DSC. By plotting densities vs. molar mass, the
diagram obtained has correspondence to similar observations in other solid metal–lutidine complex
systems.
Keywords: FT-IR spectrometry, host–guest phenomenon, manganese(II) chloride–lutidine
(dimethylpyridine) complexes
Introduction
Pyridine and its derivatives are among the best-known heterocyclic nitrogen ligands.
The co-ordination chemistry with pyridine-type ligands has been studied widely.
Metal complexes of higher fatty acids with pyridine exhibit interesting thermo-
chemical properties [1]. Transition metal salts with pyridine and methylpyridines of-
ten give inclusion compounds when stable guest molecules are placed in the holes,
channels or layers of the host compound [2]. During the thermal treatment of such
compounds, in the first decomposition step the guest molecules evaporate without
destroying the host matrix.
*
Author for correspondence: E-mail: kati@tki.aak.bme.hu
1388–6150/2004/ $ 20.00
Akadémiai Kiadó, Budapest
© 2004 Akadémiai Kiadó, Budapest
Kluwer Academic Publishers, Dordrecht

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MÉSZÁROS SZÉCSÉNYI et al.: PYRIDINE-TYPE COMPLEXES
In our previous studies on copper(II) halide complexes [3–5] with methylpyridine
derivatives, we have investigated the relationship between the methyl group(s) position
and the structure as well as the thermal stability of the complexes formed. These com-
pounds also reveal the host–guest phenomenon. The present paper deals with the struc-
tural characterisation and thermal decomposition of the manganese(II) chloride com-
plexes with 3,4- and 3,5-lutidine. A special attention was paid to examine the ‘zeolitic
property’ of the compounds.
Experimental
All chemicals used were of analytical reagent grade.
The compounds were synthesised by mixing warm methanolic solutions of the
ligand (25 mmol) and manganese(II) chloride (2.5 mmol). The total volume of the
mixture was about 5 cm3. The very pale pink precipitates were obtained at room tem-
perature. The compounds formed were washed with cold MeOH and Et2O and dried
at room temperature. Reaction time: 24 h.
The IR-spectra were recorded in the range of 4000–150 cm–1 on a Perkin Elmer
System 2000 FT-IR spectrometer at room temperature using KBr pellets in the
mid-IR range and polyethylene pellets in the far-IR range. The spectra were obtained
with a resolution of 4 cm–1 and with a co-addition of 16 scans.
The thermal analysis in the temperature range up to 600 K was carried out in a
flowing nitrogen atmosphere using a DuPont 2000 TA system with a thermobalance
DuPont 951 TGA and a platinum crucible sample holder. The DSC curves were re-
corded in aluminium pan sample holder with an empty aluminium pan as reference.
The heating rate was 10 K min–1.
The unit cell parameters were obtained by transmission X-ray powder diffrac-
tion using a Guinier–Hägg focusing camera with Cu and CrKα1 radiation [3].
Results and discussion
The compounds were characterised by thermal methods, FT-IR spectrometry and
X-ray powder diffraction.
Because of the steric hindrance of the methyl groups, with 3,5-lutidine (3,5-Lu)
only bis(ligand) complex is obtained, while with 3,4-lutidine (3,4-Lu) a tetrakis de-
rivative is formed. The thermogravimetric and DSC curves of the compounds are pre-
sented in Fig. 1. The decomposition is endothermic (DSC curves) in the full tempera-
ture range. The thermogravimetric curve shows that the bis(ligand) complex is stable
up to 440 K. Its decomposition takes place in three steps which stoichiometry may be
presented by the following scheme where in parenthesis the corresponding calculated
value is given:
Mn(3,5-Lu)2Cl2→Mn(3,5-Lu)Cl2+3,5-Lu
33% (31.50%)
13% (15.75%)
Mn(3,5-Lu)Cl2 →Mn(3,5-Lu)0.5Cl2+0.5(3,5-Lu)
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Fig. 1 DTG, TG and DSC curves of ––— Mn(3,4-Lu)4Cl2 and ----- Mn(3,5-Lu)2Cl2
Mn(3,5-Lu)0.5Cl2 →MnCl2+0.5(3,5-Lu)
15 % (15.75%)
The decomposition of Mn(3,5-Lu)2Cl2 is finished at 590 K.
The tetrakis(ligand) complex begins to decompose at room temperature and the
composition of the thermally stable compound, calculated on the basis of the
thermoanalytical data is Mn(3,4-Lu)3.5Cl2. Its decomposition begins at 380 K. In the
temperature range of 380–450 K two superposed steps can be distinguished which re-
fer to the evaporation of 1.5(3,4-Lu) and (3,4-Lu), respectively. The whole process
can be presented as
Mn(3,4-Lu)3.5Cl2→Mn(3,4-Lu)Cl2+2.5(3,4-Lu)
54.3% (53.56%)
In the 450–530 K range no mass change is observed. The composition of the in-
termediate corresponds to Mn(3,4-Lu)Cl2 which above 530 K decomposes in two
steps to MnCl2:
1
Mn(3,4-Lu)Cl2→Mn(3,4-Lu) 2/3Cl2+ 3,4-Lu
7.1% (7.14%)
3
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2
Mn(3,4-Lu) 2/3Cl2→MnCl2+ 3,4-Lu
13.4% (14.28%)
3
The calculated values are given in parenthesis.
The intermediate has been isolated and its structure was examined by both the
IR-spectrometry and transmission X-ray power diffraction.
The IR assignments for Mn(3,4-Lu)4Cl2 and its intermediate, Mn(3,4-Lu)Cl2,
are presented in Tables 1a and b, respectively, while those of Mn(3,5-Lu)2Cl2 are
Table 1a IR assignments of Mn(3,4-Lu)4Cl2
A¢
Assignment
Assignment
′
A
3048 m
2948 m
2948 m
2923 m
2923 m
1607 vs
1560 m
1496 vs
1465 sh
1447 s
1419 s
1387 s
1377 m
1312 m
1240 m
1199 vs
1178 m
1150 w
1078 s
1008 m
857 s
νCH
2948 m
2948 m
1465 sh
1066 sh
1027 m
825 s
νCH3
νCH3
νCH3
νCH3
δeCH3, δCH3
νCH3
δeCH3, δCH3, γCCH3
δeCH3, δCH3
νCH3
νCC, νCN
γCCH, τCN
νCN, νCC
719 sh
532 m
430 s
τCC, τCN, γCCH3
γCCH3, τCC, τCN
τCC, γCCH3, γCCH, τCN
τCC, τCN
βCCH, νCC, νCN
δCH3, νCCH3
δCH3, δeCH3, νCC
δCH3, δeCH3
≈165 s
–
δeCH3, δCH3, βCCH
βCCH, νCC, δeCH3
ring vibration
νCN, νCC, βCCH
βCCH, βCCC, νCCH3, δeCH3
βCCH, νCC, νCCH3
βCCH, νCC, νCCH3
ring vibration
δeCH3, δCH3
215 m
195 m
165 m
–
νMnCl
νMnCl
νMnN
842 s
free ligand
free ligand
free ligand
free ligand
832 s
725 s
423 w
βCCC, βCNC, νCCH3, βCCH
βCCC, νCCH3
βCCC, νCCH3
νCCH3, βCCH3
βCCH3
755 m
607 s
520 m
413 w
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MÉSZÁROS SZÉCSÉNYI et al.: PYRIDINE-TYPE COMPLEXES
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listed in Table 2. The ligand’s bands were assigned on the basis of the free ligand’s
spectrum [6], while the bands characteristic for the complex (νMnN and νMnCl)
were determined using spectral data on Mn(py)2Cl2 (py=pyridin) [7]. In the IR spec-
trum of Mn(3,4-Lu)4Cl2 the shifts of the characteristic pyridine vibrations
(605→612 and 423→430 cm–1) are in accordance with the literature data. On the ba-
sis of the position of the νMnN vibration (180 cm–1), for Mn(3,4-Lu)4Cl2 a polymeric
octahedral geometry may be assumed. The presence of the free ligand bands in the
spectrum of the freshly prepared sample refer to a host–guest interaction in the com-
plex. On the basis of the IR-spectrum, to the structure of the isolated intermediate,
Mn(3,4-Lu)Cl2, also a polymeric octahedral structure may be ascribed.
Table 1b IR assignments of Mn(3,4-Lu)Cl2
′
A¢
Assignment
A
Assignment
2952 w
2952 w
2928 w
2928 w
1610 s
1559 w
1502 m
1458 sh
1443 m
1420 m
1390 m
1377 m
1313 w
1242 w
1202 s
1177 w
1145 vw
1079 s
1003 w
917 w
νCH3
2952 w
2952 w
1458 sh
1458 sh
1059 w
1017 m
824 s
νCH3
νCH3
νCH3
νCH3
δeCH3, δCH3
νCH3
δeCH3, δCH3
νCC, νCN
δeCH3, δCH3, γCCH3
δeCH3, δCH3
νCN, νCC
βCCH, νCC, νCN
δCH3, νCCH3
δCH3, δeCH3, νCC
δCH3, δeCH3
δeCH3, δCH3, βCCH
βCCH, νCC, δeCH3
ring vibration
νCN, νCC, βCCH
γCCH, τCN
718 s
γCC, τCN, γCCH3
γCCH3, γCC, τCN
τCC, γCCH3, γCCH, τCN
529 m
433 m
–
235 br m
205 br m
180 br m
–
νMnCl
νMnCl
νMnN
bCCH, bCCC,n CCH3,d CH3
e
bCCH, nCC,n CCH3,
bCCH, nCC, nCCH3
ring vibration
606 m
423 m
free ligand
free ligand
deCH3, dCH3
deCH3
859 s
βCCC, βCNC, νCCH3, βCCH
βCCC, νCCH3
βCCC, νCCH3
νCCH3, βCCH3
βCCH3
755 w
612 m
521 m
414 vw
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MÉSZÁROS SZÉCSÉNYI et al.: PYRIDINE-TYPE COMPLEXES
Table 2 IR assignments for Mn(3,5-Lu)2Cl2
Assignment
A1
Assignment
B2
3039 m
2950 m
2916 m
1601 s
1461 s
1444 s
νCH
2950 m
2916 m
1461 s
νCH3
νCH3
νCH3
nCH3
δCH3, δeCH3, νCC
δCH3
νCC, νCN
1427 sh
1376 m
1331 m
βCCH, νCC, νCN, δCH3, δeCH3
δCH3, δeCH3
βCCH, νCC, δCH3
βCCH, νCC, νCN
νCN, βCCH, νCC,
νCCH3
βCCH, νCH3, νCN
1376 m
1246 m
1174 s
930 w
νCCH3, νCC, βCCH,
βCCC
βCCH, βCCC, νCCH3, δCH3, δeCH3
1148 s
1037 s
992 vw
748 vs
537 m
279 w
ring vibration
B1
νCC, νCN, βCCC
δeCH3, δCH3
2950 m
1444 s
1037 s
930 w
865 vs
698 vs
412 w
–
νCH3
δCH3, δeCH3
δeCH3, δCH3
γCCH
βCCC, νCCH3, νCC, βCCH
βCCC, νCCH3
βCCH3
ring vibration
τCN, τCC
A2
2950 m
1444 s
1037 s
959 w
943 w
–
νCH
γCCH3, τCC, τCN
δCH3, δeCH3
δeCH3, δCH3
ring vibration
γCCH
2865 m
2729 w
2493 w
1861 w
1795 w
hybride band
hybride band
hybride band
hybride band
hybride band
224 s
202 s
170 s
νMnCl
νMnCl
νMnN
In the spectrum of Mn(3,5-Lu)2Cl2 both of the νMnCl bands (224 and 202 cm–1)
and a νMnN band (170 cm-1) are assigned. The vibration at 397 cm–1 in the
free 3,5-lutidine ligand is shifted to a higher frequency (412 cm–1). For this com-
pound also a polymeric octahedral structure may be characteristic.
The calculated and refined unit cell dimensions for Mn(3,5-Lu)2Cl2, Mn(3,4-
Lu)4Cl2 and those of the Mn(3,4-Lu)Cl2 intermediate are given in Table 3, while a part
of characteristic X-ray patterns of the same compounds are presented in Tables 4a–c.
Both of the 3,4-lutidine complexes are monoclinic, while the crystal structure of
Mn(3,5-Lu)2Cl2 is simple tetragonal. The full set of refined and indexed monophase
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Table 4 The first part of characteristic X-ray powder pattern obtained by transmission
Guinier-technique
h
k
l
2θ-obs.
2θ-calc.
D-obs.
Intensity
a) Mn(3,4-L)4Cl2
1
0
1
2
0
0
2
1
2
3
1
0
1
0
1
1
1
1
1
0
2
9.183
10.840
11.470
11.801
14.133
17.717
15.261
16.471
19.555
19.933
9.171
10.839
11.464
11.775
14.124
17.716
15.251
16.462
19.554
19.948
9.6227
8.1551
7.7088
7.4931
6.2614
6.0145
5.8011
5.3776
4.5358
4.4507
22
98
10
8
0
0
–1
1
51
5
0
1
5
–1
1
13
100
59
–1
b) Mn(3,4-L)Cl2 intermediate
–1
1
0
0
0
0
0
0
1
1
1
0
1
1
2
2
1
2
0
0
2
0
7.840
9.373
7.825
9.354
44.2672
9.4283
6.1266
5.6431
5.1537
4.7261
3.7786
3.6981
3.1032
3.1032
62
100
30
8
0
14.446
15.691
17.192
19.761
23.526
24.045
27.669
28.745
14.430
15.687
17.180
18.770
23.543
24.028
27.652
28.721
–2
3
17
2
2
0
11
11
45
6
1
–1
6
c) Mn(3,5-L)2Cl2
1
2
2
3
3
0
2
2
2
3
1
1
2
1
2
0
0
1
2
1
0
0
0
0
0
1
1
1
1
1
13.109
20.856
26.475
29.683
33.972
34.974
39.920
41.090
44.417
46.539
13.164
20.884
26.507
29.703
33.985
34.987
39.940
41.098
44.425
46.537
10.0297
6.3253
4.9997
4.4696
3.9190
3.8101
3.3539
3.2623
3.0289
2.8980
100
5
17
8
6
10
5
54
6
3
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X-ray diffraction data can be obtained upon request from the corresponding author. At-
tempts to study the 3D-molecular arrangement in Mn(3,4-Lu)4Cl2 by single-crystal
technique also confirmed the symmetry and dimensions derived by powder methods.
However, the detailed structure was not of a quality to be published probably due to a
complex twinning growth [8].
The corresponding copper(II) complexes show the host–guest interaction and
the host molecules are those with two ligand molecules, i.e., by thermal decomposi-
tion of Cu(3,4-Lu)4Cl2 and Cu(3,5-Lu)3.25Cl2 bis(ligand) complexes are obtained [5].
On the contrary, in manganese(II) complexes the IR-spectra and the thermal proper-
ties may refer to the host–guest phenomenon only in the case of Mn(3,4-Lu)4Cl2. In
the Mn(3,5-Lu)2Cl2 no zeolitic effect was observed. While the thermal stability of
Cu(3,4-Lu)2Cl2 is poor, the corresponding Mn(3,4-Lu)2Cl2 cannot be isolated. In the
case of the manganese(II) compound, the composition of the relatively stable inter-
mediate is Mn(3,4-Lu)Cl2. The thermal decomposition pattern of the corresponding
manganese(II) and copper(II) complexes is also different. However, there is a good
correlation between the density and the molar mass data of the corresponding
manganese(II) and copper(II)–lutidine complexes as is shown in Fig. 2. We use this
simple relation in order to enhance the veracity of the findings. The precision to ob-
tain the proper cell dimension after having used a trial-and-error calculation with ac-
curate data is very high. Of this reason, small deviations from the regular diagram
forebode a structural property. On this basis it may be assumed a host and guest ex-
change in the case of Mn(3,4-Lu)4Cl2, as it is suggested by the presence of the
free-ligand bands in the IR-sepctrum of the compound, and which have vanished in
the spectrum of the corresponding intermediate.
Fig. 2 Calculated density vs. molar volume and mass
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References
1 M. Pajtášová, E. Jóna and P. Šimon, J. Therm. Anal. Cal., 67 (2002) 129.
2 V. A. Logvinenko and D. V. Soldatov, J. Therm. Anal. Cal., 56 (1999) 485.
3 K. Mészáros Szécsényi, T. Wadsten, B. Carson, É. Bencze, G. Kenessey, F. F. Gaál and
G. Liptay, Thermochim. Acta, 340–341 (1999) 255.
4 K. Mészáros Szécsényi, T. Wadsten, B. Carson, É. Bencze and G. Liptay, J. Therm. Anal.
Cal., 68 (2002) 81.
5 K. Mészáros Szécsényi, T. Wadsten, B. Carson, É. Bencze, G. Kenessey, F. F. Gaál and
G. Liptay, Thermochim. Acta, 316 (1998) 75.
6 J. A. Draeger, Spectrochim. Acta, 39A (1983) 809.
7 K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds, Wiley,
New York 1986.
8 I. Csöregh, Private Communication, 2002.
J. Therm. Anal. Cal., 75, 2004