10
P.O. Dunstan / Thermochimica Acta 450 (2006) 5–11
Table 7
Auxiliary data and enthalpy changes of the ionic complex formation in the
gaseous phase (kJ mol−1
)
Compound
ꢀfH◦
ꢀrH◦
ꢀfiH◦
−
Br(g)
−219.07a
2+
Mn(g)
2522.0 0.1b
2751.6 2.3b
2841.7 3.4b
2930.5 1.5b
3054.5 2.1b
2781.0 0.4b
2+
Fe(g)
2+
Co(g)
2+
Ni(g)
2+
Cu(g)
Zn(g)
2+
[MnBr2(p-clan)2](g)
[FeBr2(p-clan)2](g)
[CoBr2(p-clan)2](g)
[NiBr2(p-clan)2](g)
[CuBr2(p-clan)2](s)
[ZnBr2(p-clan)2](g)
−418
6
7
5
5
−340.7 5.2
−2605
−2726
−2772
−2856
7
8
6
6
−366
−330
6
4
−320.8 4.7
−316.8 4.6
−299.4 3.3
−174.0 5.4
−366.2 4.0
−2892.6 6.4
−2811.3 4.9
a
Fig. 1. Plot of the enthalpy changes of complex formation in the gaseous phase
from ionic components against d-electron configuration.
Ref. [37].
b
Ref. [38].
References
decrease of the electronic density on the nitrogen atom of
aniline.
Theenthalpychangesfortheprocessesofhypotheticaladduct
formations in the gaseous phase from metal(II) ions, bromide
ions and p-chloroaniline molecules can be evaluated:
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27 (5) (1965) 1105.
M(g)2+ + 2Br(g)− + 2p-clan(g)
,
ΔfIH◦
(6)
[9] K.R. Manolov, Zh. Neorg. Khim. 11 (3) (1966) 684.
[10] I.S. Ahuja, Indian J. Chem. 7 (1969) 509.
2+
−
withꢀfIH◦ =ꢀfH◦(adduct(g))−ꢀfH◦(M(g) −2 ꢀfH◦(Br(g)
)
− ꢀfH◦(p-clan(g)).
[11] P.O. Dunstan, Thermochim. Acta 441 (2006) 1.
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2nd ed., Pergamon Press, London, 1964, p. 80–82, 85, 87–88.
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371.
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(1976) 384.
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149.
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(1973) 93.
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Table 7 lists the values obtained for these enthalpy values.
The environment around the Mn(II) ions in the solid state is
pseudo-tetrahedral only in the cases of Fe(II), Co(II) and Cu(II)
ions, as different atoms (two bromide ions and two nitrogen
atoms) are present. Supposing than in the gaseous phase, all the
twobromideionsandtwonitrogenatoms, itispossibleandbetter
to find correlations of the ꢀfIH◦ values rather than to get corre-
¯
lations of the (D(M−N)) values. The correlation with the metal
atomic number is present in the Fig. 1. It is seen part of the dou-
ble periodic variation profile of the first series of the transition
elements. The ꢀfIH◦ values obtained depends on the electronic
structure of the central ion. The course of that relation allows
determining graphically the thermodynamic stabilization energy
in the ligand field on the assumption that the course of variation
of the enthalpies values is linear in a hypothetical state without
the influence of the ligand field. In such a case the stabilization
energies are the difference between the real and the interpo-
lated values. Thus, it is found that the stabilization energies in
the ligand field formed by two bromide ions and two nitrogen
atoms (from two ligand molecules) decreases in the order: Ni(II)
(129 kJ/mol) > Cu(II) (125 kJ/mol) > Co(II) (87 kJ/mol) > Fe(II)
(78 kJ/mol). This is nearly the same order obtained for compara-
ble adducts of aniline [11], only with the inversion of the Co(II)
and Fe(II) ions.