1
052
CHIMATADAR et al.
–
3
3
–1
sequence described here is consistent with the reaction
product and mechanistic and kinetic studies.
1
/[TRP] × 10 , dm mol
0
2
4
6
8
10
12
4
3
2
1
0
5
0
0
0
0
0
REFERENCES
1
. D. H. Macartney and A. McAuley, Inorg. Chem. 22,
062 (1983); M. A. Siddiqui, C. S. Kumar, U. Chandra-
0
0
0
2
4
3
2
1
iah, and S. Kandlikar, Indian J. Chem., Sect. A: Inorg.,
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S. Acharya, G. Neogi, R. K. Panda, and
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2
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2
. R. I. Haines and A. McAuley, Coord. Chem. Rev. 39, 77
(1981); K. Nag and A. Chakravarty, Coord. Chem. Rev.
0
10
20
3
3, 87 (1980); B. C. Verma, S. B. Kalia, and B. S. Man-
–
3
–1
1
/[OH ], dm mol
has, Indian J. Chem., Sect. A: Inorg., Bio-inorg., Phys.,
Theor. Anal. Chem. 36, 160 (1997); S. Bhattacharya,
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Fig. 5. Verification of rate law (5) in the form of Eq. (6).
1
70, 47 (1998).
3
4
. D. S. Mahadevappa, K. S. Rangappa, N. M. Gouda,
Rate law (5) can be rearranged to the equation
and B. Thimmegowda, Int. J. Chem. Kinet. 14, 1183
(
1982).
1
1
1
1
k
-
------ = ----------------------------------------------- + ----------------------- -- + --, (6)
. M. K. Mahanti and D. Laloo, J. Chem. Soc., Dalton
Trans., p. 311 (1990); R. M. Kulkarni, D. C. Bilehal, and
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(2003); K. Nag and A. Chakravarthy, Coord. Chem. Rev.
–
k
kK [TRP]
obs
kK K [TRP][OH ]
5
4
5
which can conveniently be used for verification.
3
3, 77 (1980).
According to Eq. (6), the plots of 1/k versus
obs
–
5. P. D. Pol, C. P. Kathari, and S. T. Nandibewooor, Transi-
tion Met. Chem. 28, 209 (2003); D. C. Bilehal, R. M. Kul-
karni, and S. T. Nandibewoor, Inorg. React. Mech. 4, 103
1
/[TRP] and 1/kobs versus 1/[OH ], other conditions
being constant, should be linear and are found to be
so (Fig. 5). The slopes and intercepts of these plots
were used to determine K K , and k, (0.31 ±
(2002).
4
5
3
–1
4
3
–1
0
(
.02) dm mol , (4.47 ± 0.22) × 10 dm mol , and
11.1 ± 0.3) × 10 s , respectively. The effect of ionic
6. S. Bhattacharya, B. Saha, A. Datta and P. Banerjee,
Coord. Chem. Rev. 47, 170 (1998); R. I. Haines and
A. McAuley, Coord. Chem. Rev. 39, 77 (1981).
–
2 –1
strength and permittivity could not be explained
because of the involvement of various ionic species in
the reaction. The suggested mechanism is supported
by the moderate values of the thermodynamic activa-
7. P. Ray, in Inorganic Synthesis, 5th ed., Ed. by T. Moellar
(McGraw-Hill, New York, 1957), p. 201.
8
9
. G. H. Jaffery, J. Bassett, J. Mendham and R. C. Den-
ney, in Vogel’s Textbook of Quantitative Chemical
Analysis, 5th ed. (ELBS, Longman, Essex, U.K.,
1996), p. 462.
#
tion parameters. The high negative ∆S value suggests
that the complex is more ordered than the reactants.
The observed moderate enthalpy of activation and a
higher rate constant for the slow step indicate that oxi-
dation presumably occurs via an inner-sphere mecha-
nism. This conclusion is supported by earlier observa-
tions [17].
. G. P. Panigrahi and P. K. Misro, Indian J. Chem., Sect. A:
Inorg., Bio-inorg., Phys., Theor. Anal. Chem. 16, 201
(1978).
1
0. K. Randrerath, Thin Layer Chromatgraphy (Academic,
New York, 1968), p. 101.
CONCLUSIONS
11. I. M. Kolthoff, E. J. Meehan, and E. M. Carr, J. Am.
Chem. Soc. 75, 1439 (1953); A. A. Frost and R. G. Pear-
son, Kinetics and Mechanism (Wiley Eastern, New
Delhi, 1970), p. 367.
Among various Ni(IV) forms in alkaline media,
the active Ni(IV) form is found to be
3–
[
Ni(OH) (H IO )(H IO) ] for the reaction studied.
2 3 6 2 6
12. U. Chandraiah, C. P. Murthy and S. Kandlikar, Indian J.
Chem., Sect. A: Inorg., Bio-inorg., Phys., Theor. Anal.
Chem. 28, 248 (1989); R. M. Kulkarni, D. C. Bilehal,
and S. T. Nandibewoor, J. Chem. Res. 147, 401
(2002).
Medium pH plays a crucial role. The rate constants for
the slow step involved in the mechanism were evaluated
and the activation parameters with respect to the slow
reaction step were computed. The overall mechanistic
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A Vol. 81 No. 7 2007