FORMATION CONSTANTS AND COMPOSITION OF Ga3+ AND In3+ COMPLEXES
1501
complex forms formed by the metal ions with IDSA at the values change symbatically. The protonation of
3+
different pH values. The diagrams are shown in Figs. 2
M
complexonates is probably accompanied by a
and 3. The pH range in which the neutral indium and decrease in ligand dentation by analogy with the
3+
gallium complexes of IDSA exist is shifted to the acid Ga –EDTA complex [11]. This study showed that
region and amounts to two pH units, which is considꢀ the protonated acetate branch was not involved in
erably smaller than the same range for Group II catꢀ complexation and its site in the octahedron around
ions. The discovered neutral indium and gallium comꢀ gallium(III) was occupied by the water molecule.
plexes are highly stable.
A comparison of the stability of the neutral comꢀ
plexes of the metals under study with that of the neuꢀ
ACKNOWLEDGMENTS
This study was financially supported by the federal
tral aluminum complex ( log
β
= 16.48 [2]) showed
0
grant program “Scientific and Academic Specialists
for Innovations in Russia” for 2009–2013 (project
no. 14.B37.21.0653) and the program “Participant of
the Innovation Competition of Young Researchers
UMNIK” (state contract no. 10509r/16886 of June 8,
that the former was ~2.5 orders of magnitude higher.
3+
3+
This suggests that the bond of Ga and In with the
complexon atoms capable of polarization is more
3+
covalent than the chemical bond of Al with the same
atoms of IDSA. This behavior of gallium and indium
is explained by the presence of a bulky 18ꢀelectron
2012).
2
1
shell under their valence electron shell (ns np ); this
shell imparts specific polarization properties to these
metals, namely, easy deformability and aptitude
toward additional polarization.
REFERENCES
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Green Chem. , 410 (2003).
5
We can thus assume that the stability of the comꢀ
plexes increases with the covalent component of the
2. L. N. Tolkacheva and V. M. Nikol’skii, Russ. J. Phys.
Chem. A 86, 396 (2012).
3+
3. R. P
ribil, Komplexony v chemické analyse (NCSAV,
M –ligand bond. The approximately equal log valꢀ
β
Praha 1957; Inostr. Liter., Moscow, 1960).
3+
3+
ues for Ga and In complexes with IDSA can be
explained by the structural match between the central
ions and the ligand. The most stable complexes are fluꢀ
oride complexes for gallium with its relatively small
ionic radius and chloride and bromide complexes for
indium and thallium, which have large ionic radii. The
gallium ion with its relatively small ionic radius is
likely to form more stable complexes with the small
IDSA ligand than the indium ion, whose ionic radius
is larger. For EDTA with its large molecule and more
mobile skeleton, this anomaly is not observed, the stabilꢀ
ity of neutral complexes steadily increasing from alumiꢀ
4
5
6
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Complexones and Metal Complexonates (Khimiya, Mosꢀ
cow, 1988).
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the Preparation of Titrated Solutions, 5th ed. (Khimiya,
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lation of Chemical Equilibria (Mos. Gos. Univ., Mosꢀ
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The Hydrolysis of Metal Ions in Diluted Solutions (Atomizꢀ
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7
8
. L. N. Tolkacheva and V. M. Nikol’skii, Vestn. Tver.
Univ., Ser. Khim. 13 (7), 29 (2012).
num to indium: log
β
(16.3) < log
β
(20.3) <
GaL
AlL
log
β
(25.0) at
I
= 0.1 and 20 С [4].
°
InL
9. V. P. Vasil’ev, Thermodynamic Properties of Electrolyte
Solutions (Vysshaya Shkola, Moscow, 1982) [in Rusꢀ
sian].
Since IDSA remains a tetradentate (but never penꢀ
tadentate) ligand in most of its complexes, we can
assume that with Subgroup IIIA elements, this comꢀ 10. R. G. Bates, Determination of pH: Theory and Practice
(
Wiley, New York, 1964).
bered glycine rings and one sixꢀmembered alanine 11. T. I. Polynova and M. A. PoraiꢀKoshits, Itogi Nauki
Tekh., Kristallokhim. 18, 64 (1984).
plexon is also tetradentate, forming two fiveꢀmemꢀ
ring.
The protonated complexes are clearꢀcut acids.
They are much less stable than neutral complexes, and
Translated by L. Smolina
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A
Vol. 87
No. 9 2013