134
M. Olczak-Kobza / Thermochimica Acta 366 (2001) 129±134
unassociated N±H group gives a nNH band at
3480 cm 1 and dNH band at 1449 cm 1 [16]. In com-
pounds with metals the nNH band is shifted towards
ꢂ IR spectra analysis demonstrated that in the synth-
esis reaction, neutral molecules of imidazole or 4-
methylimidazole are bound with Cd(Sal) and
Cd(Salox); the acidic hydrogen bound to N-1 nitro-
gen is not transferred to cadmium mono-com-
plexes.
ꢂ The thermal decomposition of the complexes is a
multi-stage process. The intermediate product is
Cd(Im)2 in the case of imidazole complexes, and
Cd(Sal) and Cd(Salox) in the case of 4-methylimi-
dazole complexes.
ꢂ The thermal stability of the complexes is lower than
the stability of cadmium mono(o-hydroxybenzo-
ate) or cadmium mono(o-hydroxybenzaldoximate).
Cd(Sal)(HIm)2 (ti 170ꢁC) is the most stable, and
Cd(Salox)(4-MHIm)2 (ti 55ꢁC) the least stable
of the complexes.
1
lower frequencies to about 3300 cm and the dNH
band is often invisible or appears within the range
1400±1450 cm 1 [17]. For Cd(Im)2(HIm), a nNH band
is observed at 3381 cm 1(s) and a dNH band appears at
1
1418 cm (m). These bands are not found in the
spectrum of Cd(Im)2. In the spectra of Cd(Sal)(HIm)4
and Cd(Sal)(HIm)2, nNH bands are present at
1
1
3385 cm
Their intensity diminishes as the number of imidazole
(m) and 3380 cm
(sh), respectively.
molecules in the complex decreases. The dNH band
1
observed at 1410 cm
(sh) in the spectrum of
Cd(Sal)(HIm)4 disappears in the case of the complex
with two molecules of imidazole. The presence of nNH
and dNH bands in the spectrum suggests that neutral
molecules of imidazole also join with the mono-
complex of cadmium, although it does not show
whether they are all unassociated.
The spectra of compounds with 4-methylimidazole
are considerably more dif®cult to interpret. The bands
in the spectra of Cd(Sal)(4-MHIm)4 and Cd(Salox)(4-
References
[1] Z. Marczenko, Organic Reagents in the Inorganic Analysis,
PWN, Warszawa, 1959, p. 86 and p. 359.
1
1
MHIm)2 observed at 3393 cm (w) and 3360 cm
[2] A.K. Babko, L.L. Szewczenko, Zh. Neorg. Khim. 9 (1964)
42.
(w), respectively, may be attributed to nNH vibrations
which indicates the presence of neutral 4-methylimi-
dazole molecules in the complex. This conclusion may
con®rm the proposed course of thermal decomposition
involving the presence of Cd(Sal) and Cd(Salox) in the
solid products.
[3] J. Rynasiewicz, J.G. Flagg, Anal. Chem. 26 (1954) 1506.
[4] P. Lumme, P. Knuuttila, J. Therm. Anal. 25 (1982) 139.
[5] F.P. Emmenegger, Thermochim. Acta 112 (1987) 63.
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[7] M. Olczak-Kobza, Polish J. Chem. 69 (1995) 1396.
[8] M. Olczak-Kobza, J. Therm. Anal. 55 (1999) 989.
[9] A. Turek, M. Olczak-Kobza, J. Therm. Anal. 54 (1998) 133.
[10] N.H. Sivasankarani, S. Jawaharunnissa, L. Kamakshi, Ind. J.
Chem. 29A (1990) 581.
4. Conclusions
ꢂ Simple and mixed Cd(II) complexes of the type
Cd(Im)2(HIm), Cd(Sal)(HIm)2, Cd(Sal)(HIm)4Á
H2O, Cd(Sal)(4-MHIm)4 and Cd(Salox)(4-MHIm)2
have been prepared.
ꢂ No mixed complexes have been obtained in reac-
tions of Cd mono(o-hydroxybenzoate) and cad-
mium mono(o-hydroxybenzaldoximate) with 1,2-
dimethylimidazole.
[11] A. Busnot, F. Busnot, J.F. Hemidy, J.F. Le Querler,
Thermochim. Acta 228 (1993) 219.
[12] R.W. Hay, Bio-Inorganic Chemistry, PWN, Warszawa, 1990,
p. 229.
[13] F.J. Welcher, The Analytical Uses of Ethylenediamine
Tetraacetic Acid, WNT, Warszawa, 1963, p. 149.
[14] R.J. Sundberg, R.B. Martin, Chem. Rev. 74 (1974) 473.
[15] B. Lenarcik, J. Kulig, P. Laidler, Roczniki Chem. 48 (1974)
1151.
[16] W.J. Eilbeck, F. Holmes, A.E. Underhill, J. Chem. Soc. A
(1967) 757.
ꢂ Complexes with imidazole have a crystalline struc-
ture while complexes with 4-methylimi-dazole are
amorphous.
[17] W.J. Eilbeck, F. Holmes, Ch.E. Taylor, A.E. Underhill, J.
Chem. Soc. A (1968) 128.