Manganese(II) complexes of 1,2-Di(imino-4′-antipyrinyl)ethane

Article abstract of DOI:10.1081/SIM-100106861

Manganese(II) complexes of the Schiff base 1,2-di(imino-4′-antipyrinyl)-ethane (GA) have been synthesized and characterized by elemental analyses, electrical conductance in non-aqueous solvents, infrared and electronic spectra as well as magnetic susceptibility measurements. The complexes have the general formulae [Mn(GA)X₂] (X - ClO₄, NO₃, Cl, Br or I). GA acts as a neutral tetradentate ligand coordinating through both carbonyl oxygens and both azomethine nitrogens. Both anions are coordinated to the metal ion and the perchlorate as well as nitrate ions are monodentate. A high-spin octahedral geometry is assigned around Mn(II) in all of these complexes.

Full text of DOI:10.1081/SIM-100106861

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MANGANESE(II) COMPLEXES OF 1,2-DI(IMINO-4′-
ANTIPYRINYL)ETHANE
T. M. Marykutty a , N. T. Madhu a & P. K. Radhakrishnan b
a School of Chemical Sciences, Mahatma Gandhi University , Priyadarshini Hills P O,
Kottayam, Kerala, 686560, India
b School of Chemical Sciences, Mahatma Gandhi University , Priyadarshini Hills P O,
Kottayam, Kerala, 686560, India
Published online: 15 Feb 2007.
To cite this article: T. M. Marykutty , N. T. Madhu & P. K. Radhakrishnan (2001) MANGANESE(II) COMPLEXES OF 1,2-
DI(IMINO-4′-ANTIPYRINYL)ETHANE, Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 31:7, 1239-1247, DOI:
10.1081/SIM-100106861
To link to this article: http://dx.doi.org/10.1081/SIM-100106861
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SYNTH. REACT. INORG. MET.-ORG. CHEM., 31(7), 1239–1247 (2001)
MANGANESE(II) COMPLEXES
OF 1,2-DI(IMINO-40-
ANTIPYRINYL)ETHANE
T. M. Marykutty, N. T. Madhu,
and P. K. Radhakrishnan*
School of Chemical Sciences, Mahatma Gandhi
University, Priyadarshini Hills P O, Kottayam-686 560,
Kerala, India
ABSTRACT
Manganese(II) complexes of the Schiff base 1,2-di(imino-40-
antipyrinyl)-ethane (GA) have been synthesized and char-
acterized by elemental analyses, electrical conductance in
non-aqueous solvents, infrared and electronic spectra as well
as magnetic susceptibility measurements. The complexes have
the general formulae [Mn(GA)X2] (X ¼ ClO4, NO3, Cl, Br
or I). GA acts as a neutral tetradentate ligand coordinating
through both carbonyl oxygens and both azomethine nitro-
gens. Both anions are coordinated to the metal ion and the
perchlorate as well as nitrate ions are monodentate. A high-
spin octahedral geometry is assigned around Mn(II) in all of
these complexes.
*Corresponding author. E-mail: mgu@md2.vsnl.net.in
1239
Copyright # 2001 by Marcel Dekker, Inc.
www.dekker.com

1240
MARYKUTTY, MADHU, AND RADHAKRISHNAN
INTRODUCTION
Antipyrine and its derivatives possess antibacterial1 and anti-inflam-
matory2 properties. Recently, it has been reported that a manganese complex
with terpyridine effects the four-electron oxidation of water to oxygen,
mimicking the production of oxygen from water during photosynthesis3. In
view of this, and as part of our earlier investigations on Schiff base-metal
complexes478 of antipyrine derivatives, we report here the synthesis
and characterization of a new series of Mn(II) complexes of the Schiff base 1,2-
di(imino-40-antipyrinyl)ethane (GA) which is an antipyrine derivative (Fig. 1).
RESULTS AND DISCUSSION
The formation of the complexes may be represented by the general
equation shown below.
MnX2 þ GA ! MnðGAÞX2 ðX ¼ ClO4; NO3; Cl; Br or IÞ
The elemental analyses data (Table I) of the complexes suggest that the
present complexes may be formulated as Mn(GA)X2 (X ¼ ClO4, NO3, Cl,
Br or I).
The molar conductance values of the complexes (Table II) in ace-
tonitrile, DMF and nitrobenzene (10À3 M solutions) suggest non-electrolytic
behaviour9. The slightly higher values observed in acetonitrile and DMF9
may be due to the partial displacement of coordinated anions by the
solvent molecules. Thus, the complexes may be formulated as [Mn(GA)X2]
(X ¼ ClO4, NO3, Cl, Br or I).
Figure 1. 1,2-Di(imino-40-antipyrinyl)ethane.

MANGANESE(II) COMPLEXES
1241

1242
MARYKUTTY, MADHU, AND RADHAKRISHNAN
Table II. Molar Conductance Values of the Manganese(II)
Complexes of GA (in OhmÀ1 cm2 molÀ1
)
Complex
C6H5NO2
CH3CN
DMF
[Mn(GA)(ClO4)2]
[Mn(GA)(NO3)2]
[Mn(GA)Cl2]
[Mn(GA)Br2]
[Mn(GA)I2]
7.30
4.26
3.35
4.86
90.05
87.63
48.68
48.68
30
31.76
36.32
38.00
49.01
4.8081.84.31
Infrared Spectra
The IR assignments for the relevant bands of GA and its complexes
are presented in Table III. The strong band at 1650cm À1 due to the C›O
stretching vibration of GA is shifted to the region 160471620cm À1 in the
complexes, indicating the coordination of both carbonyl oxygens7. The
strong band at 1576 cmÀ1 attributable to the C›N stretching vibration of
GA is shifted to the region 159071592 cmÀ1 in the complexes indicating the
coordination of both azomethine nitrogens10.
The perchlorate complex shows doubly split strong band maxima at
1158 and 1080 cmÀ1 and another medium intensity band at 920cm À1. These
are assigned to the v4 and v3 vibrations, respectively, suggesting unidentate
coordination of both perchlorate ions11.
The nitrate complex shows two strong bands occurring at 1420and
1315 cmÀ1 which are attributed to the n4 and n1 stretching frequencies of the
coordinated nitrate ions. Since n4Àn1 ¼ 105 cmÀ1, both nitrate ions are
unidentately coordinated.11
In the far-infrared spectra of halide complexes the Mn-Cl, Mn-Br and
Mn-I stretching vibrations7 occur at 312, 282 and 150cm À1, respectively,
which are absent in the spectrum of the free ligand. Further, the n(Mn-ÀO1)
and n(Mn-N) stretching vibrations are observed at about 540and 460cm
,
respectively, in all of the complexes7.
The above results along with the conductance data indicate that both
anions are coordinated to the metal ion in these complexes.
Electronic Spectra
The electronic spectral bands of GA and its complexes with their ten-
tative assignments are presented in Table IV. In the complexes, both n ! pÀꢂ1
and p ! pꢂ bands are found as blue-shifted to the region 27,037728,481 cm
and 41,493745,871 cmÀ1, respectively, compared to that of GA.

MANGANESE(II) COMPLEXES
1243

1244
MARYKUTTY, MADHU, AND RADHAKRISHNAN
Table IV. Electronic Spectral Data and Magnetic Moments of Manganese(II)
Complexes of GA
Compound
GA
Abs. Max. (cmÀ1
)
Tentative Assignments
m
eff(BM)
38,197
25,497
ꢀ ! ꢀꢂ
n ! ꢀꢂ
—
41,841
28,481
22,140
ꢀ ! ꢀꢂ
n ! ꢀꢂ
[Mn(GA)(ClO4)2]
[Mn(GA)(NO3)2]
[Mn(GA)Cl2]
5.82
5.91
6.00
5.83
5.85
4
6A1g ! T2g
45,871
28,115
22,142
ꢀ ! ꢀꢂ
n ! ꢀꢂ
4
6A1g ! T2g
41,493
28,037
22,511
ꢀ ! ꢀꢂ
n ! ꢀꢂ
4
6A1g ! T2g
45,045
27,442
22,525
ꢀ ! ꢀꢂ
n ! ꢀꢂ
[Mn(GA)Br2]
[Mn(GA)I2]
4
6A1g ! T2g
45,045
27,037
22,405
ꢀ ! ꢀꢂ
n ! ꢀꢂ
4
6A1g ! T2g
All the complexes show low intensity peaks around 22,000 cmÀ1 cor-
4
responding to the 6A1g ! T2g, spin forbidden transition, consistent with an
octahedral geometry12.
Magnetic Moment Data
The molar magnetic moments of the complexes are presented in Table
IV. The values lie in the 5.8276.00 BM range, very close to those expected
for high-spin octahedral geometry13.
Based on the results of the present study the structure shown in Fig. 2
may be assigned to the complexes.
EXPERIMENTAL
Materials
The metal salts, Mn(ClO4)2ꢃ6H2O, Mn(NO3)2ꢃ6H2O, MnCl2ꢃ4H2O,
MnBr2.4H2O and MnI2ꢃ4H2O, were prepared from Analar BDH

MANGANESE(II) COMPLEXES
1245
Figure 2. Tentative structure of Mn(II) complexes of GA.
manganese carbonate and the respective 50% acids and crystallizing out the
salts by evaporating the solution on a steam bath.
Preparation of the Ligand
The ligand 1,2-di(imino-40-antipyrinyl)ethane (GA) was prepared and
characterized as reported earlier6.
Preparation of Complexes
One mmol of Mn(ClO4)2ꢃ6H2O (0.3617 g), Mn(NO3)2ꢃ6H2O
(0.2869 g), MnCl2ꢃ4H2O (0.1978 g), MnBr2ꢃ4H2O (0.2867 g) or MnI2ꢃ4H2O
(0.3807 g) in acetone (10 mL) was added to a boiling suspension of 1.2 mmol
of GA (0.4294 g) in acetone (100 mL). The mixture was refluxed for about
3 h on a boiling water bath. The precipitated complex was filtered and
washed repeatedly with hot ethyl acetate to remove the excess ligand. It was
then recrystallised from acetonitrile and dried in vacuum over phospho-
rus(V) oxide. (Warning! Perchlorate salts with organic compounds are
potentially explosive. They should be handled in small quantities and with
caution.)

1246
MARYKUTTY, MADHU, AND RADHAKRISHNAN
Physical Methods of Analysis
All the complexes were analyzed for metal and halide contents by
standard methods14 and the perchlorate content by the Kurz method15. The
electrical conductance of the complexes in nitrobenzene, DMF and ace-
tonitrile (10À3 M solutions) were measured at room temperature using a
Toshniwal conductivity bridge with a dip-type conductance cell (cell constant
0.9737). The infrared spectra of the ligands and the complexes were recorded
in the range 4000–400 cmÀ1 on a Shimadzu IR 470spectrophotometer in
KBr disc and in the range 4007200 cmÀ1 on a Perkin Elmer 983 IR spec-
trophotometer in polyethylene powder. The electronic spectra of the ligands
and the complexes in the solid state (paste with Nujol) were measured in the
range 200–1100 nm on a Shimadzu UV 160 A spectrophotometer. The ele-
mental analyses (C, H and N) were carried out on a Heraeus CHNO rapid
analyzer. The magnetic moments were measured at room temperature by
the Gouy method using mercury(II)tetrathiocyanatocobaltate(II) as the
calibrant.
ACKNOWLEDGMENTS
We thank the Head, Regional Sophisticated Instrumentation Centre,
Indian Institute of Technology, Chennai, for some instrumental analyses.
We also thank the University Grants Commission, New Delhi, India, for
granting a Teacher Fellowship to one of us (TMM).
REFERENCES
1. Alaudeen, M.; Abraham, A.; Radhakrishnan, P.K. Synthesis and
Antibacterial Activity of Rare Earth Perchlorate Complexes of 4-(20-
Hydroxynaphthylazo)antipyrine. Proc. Indian Acad. Sci. (Chem. Sci.)
1995, 107 (2), 1237126.
2. Singh, L.; Mohan, G.; Parashar, R.K.; Tripathi, S.P.; Sharma, R.C.
Studies on Anti-inflammatory Activity of Some Lanthanone Com-
plexes of Bioactive Organic Molecules. Curr. Sci. 1986, 55, 8467848.
3. Limurg, J.; Vrettos, J.S.; LiableSands, L.M.; Rheingold, A.L.; Crab-
tree, R.H.; Brudvig, G.W. A Functional Model for O-O Bond For-
mation by the O-2-evolving Complex in Photosystem II. Science 1999,
283 (5407), 152471527.
4. Radhakrishnan, P.K.; Indrasenan, P.; Nair, C.G.R. Complexes of
Lanthanide Nitrates with 4-N-(20-Hydroxybenzylidene)-Amionoanti-
pyrine. Polyhedron 1984, 3 (1), 67770.

MANGANESE(II) COMPLEXES
1247
5. Joseph, S.; Radhakrishnan, P.K. Yttrium and Lanthanide Iodide
Complexes of N,N0-Bis(4-antipyrylmethylidene)ethylenediamine.
Polyhedron 1999, 18, 1884.
6. Madhu, N.T.; Radhakrishnan, P.K. Complexes of Nickel(II) with 1,2-
Di(imino-40-antipyrinyl)ethane and 4-N-(40-Antipyrylmethylidene)-
aminoantipyrine. Synth. React. Inorg. Met.-Org. Chem. 2000, 30 (8),
156171579.
7. Madhu, N.T.; Radhakrishnan, P.K. Cobalt(II) Complexes of 1,2-
(Diimino-40-antipyrinyl)ethane and 4-N-(40-Antipyrylmethylidene)-
aminoantipyrine. Trans. Met. Chem. 2000, 25, 2877292.
8. Madhu, N.T.; Radhakrishnan, P.K. Copper(II) Complexes of 1,2-
Di(imino-40-antipyrinyl)ethane and 4-N-(40-Antipyrylmethylidene)-
aminoantipyrine. Synth. React. Inorg. Met.-Org. Chem. 2001, 31 (2), ꢀ.
9. Geary, W.J. The Use of Conductivity Measurements in Organic Sol-
vents for the Characterisation of Coordination Compounds. Coord.
Chem. Rev. 1971, 7, 81722.
10. Liu Guofa; Na Chongwu; Li Bin; Mao Kunyuan. Complexes of
Lanthanide Nitrates with a Schiff Base Derived from o-Vanillin and
p-Toluidine. Polyhedron 1990, 9, 201972022.
11. Nakamoto, K. Coordination Compounds. In Infrared and Raman
Spectra of Inorganic and Coordination Compounds, 4th Ed.; John Wiley
and Sons, Inc.: New York, 1986; 253, 254.
12. Lever, A.B.P. Electronic Spectra of dn Ions. In Inorganic Electronic
Spectroscopy, 2nd Ed.; Elsevier: Amsterdam, 1984; 449.
13. Valavi, S.G.; Yusuff, K.K.M. Synthesis and Characterisation of Some
Transition Metal Complexes of 2,3-Bis-hydrazinoquinoxaline. Synth.
React. Inorg. Met.-Org. Chem. 1995, 24 (8), 130971318.
14. Bassett, J.; Denney, R.C.; Jeffery, G.H.; Mendham, J. Titrimetric
Analysis. In Vogel’s Text Book of Quantitative Inorganic Analysis, 5th
Ed.; ELBS: London, 1961; 330, 379.
15. Kurz, E.; Kober, G.; Berl, M. Determination of Perchlorates by
Fusion with Nitrite. Anal. Chem. 1958, 30 (12), 198371986.
Received January 25, 2001
Accepted June 7, 2001
Referee I: D. E. Pennington
Referee II: L. J. Theriot