Kinetic studies of the interaction between organotin(IV)chlorides and tetraaza Schiff bases: Synthesis and characterization of some novel tin(IV) Schiff base complexes

Article abstract of DOI:10.1002/kin.20552

In this article the kinetics of the interaction between the teteraaza Schiff bases as donor with organotin(IV)chlorides as acceptor was studied in acetonitrile. Teteraaza Schiff bases are (Me₄-Bzo₂[14] tetraeneN₄) (tmtaa), (Me₄-4-CH₃Bzo ₂[14]tetraeneN₄) (Metmtaa), (Me₄-4-ClBzo ₂[14]tetraeneN₄) (Cltmtaa), i.e., [(Me₄- Bzo₂[14]tetraeneN₄)] means that (5,7,12,14- tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecine) (tmtaa) and organotin(IV)chlorides are methyltin(IV) trichloride, phenyltin(IV)trichloride, dimethyltin (IV)dichloride, diphenyltin(IV) dichloride, and dibutyltin(IV) dichloride. The kinetic parameters and the second-order k₂ rate constants show the donor properties of tetraaza Schiff bases as Me ₄-4-CH₃Bzo₂[14]tetraeneN₄ > Me₄-Bzo₂[14]tetraeneN₄ > Me ₄-4-ClBzo₂[14]tetraeneN₄ and also the acceptor properties of organotin(IV)chlorides as PhSnCl₃ > MeSnCl ₃ > Ph₂SnCl₂ > Me₂SnCl ₂ > Bu₂SnCl₂. An excellent linearity of k_obs vs. the molar concentration of the acceptor, the high span of k₂ values, the large negative values of δS^≠, and the low δH^≠ values suggest an associative (A) mechanism for the acceptor-donor interaction.

Full text of DOI:10.1002/kin.20552

Kinetic Studies of the
Interaction Between
Organotin(IV)chlorides
and Tetraaza Schiff
Bases: Synthesis and
Characterization of Some
Novel Tin(IV) Schiff Base
Complexes
ZAHRA ASADI
Chemistry Department, College of Sciences, Shiraz University, Shiraz, Islamic Republic of Iran
Received 10 May 2010; revised 29 December 2010; accepted 10 January 2011
DOI 10.1002/kin.20552
Published online 22 March 2011 in Wiley Online Library (wileyonlinelibrary.com).
ABSTRACT: In this article the kinetics of the interaction between the teteraaza Schiff
bases as donor with organotin(IV)chlorides as acceptor was studied in acetonitrile. Teter-
aaza Schiff bases are (Me4-Bzo2[14]tetraeneN4) (tmtaa), (Me4-4-CH3Bzo2[14]tetraeneN4)
(Metmtaa), (Me4-4-ClBzo2[14]tetraeneN4) (Cltmtaa), i.e., [(Me4-Bzo2[14]tetraeneN4)] means
that (5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecine) (tmtaa) and
organotin(IV)chlorides are methyltin(IV) trichloride, phenyltin(IV)trichloride, dimethyltin
(IV)dichloride, diphenyltin(IV) dichloride, and dibutyltin(IV)dichloride. The kinetic pa-
rameters and the second-order k2 rate constants show the donor properties of
tetraaza Schiff bases as Me4-4-CH3Bzo2[14]tetraeneN4 > Me4-Bzo2[14]tetraeneN4 > Me4-
4-ClBzo2[14]tetraeneN4 and also the acceptor properties of organotin(IV)chlorides as
PhSnCl3 > MeSnCl3 > Ph2SnCl2 > Me2SnCl2 > Bu2SnCl2. An excellent linearity of kobs vs. the
molar concentration of the acceptor, the high span of k2 values, the large negative values of
ꢀ
ꢀSꢀ=, and the low ꢀH= values suggest an associative (A) mechanism for the acceptor–donor
interaction. ꢁ 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 247–254, 2011
C
INTRODUCTION
Correspondence to: Zahra Asadi; e-mail: zasadi@susc.ac.ir or
zahraasadi83@yahoo.com.
Organotin(IV) complexes have been a subject of in-
terest because of their biological and commercial
Contract grant sponsor: Shiraz University Research Council.
2011 Wiley Periodicals, Inc.
c
ꢀ

248
ASADI
kinetic process were synthesized and characterized by
1H NMR,13C NMR, 119Sn NMR, IR, UV–vis spectra,
and the elemental microanalysis (C.H.N) method.
N
N
N
NH N
HN
H
H
N
N
EXPERIMENTAL
Reagents
tmtaa
porphyrin
All chemicals were used as obtained from Merck
(Germany), Fluka (Switzerland), or Acros (France). An
analytical-grade solvent from Merck was used without
further purification.
Figure 1 Comparing the structure of tmtaa and porphyrin.
applications. In recent years, there have been more
and more reports on the synthesis, antitumor activities,
and structural elucidation of various diorganotin Schiff
bases. Increasing attention has also been devoted to the
organotin(IV) complexes with the Schiff base ligand in
view of their special antitumor activities [1–4].
The observation that transition metal Schiff base
complexes can function as a neutral donor ligand has
led to several investigations of their reactions with tin
Lewis acids and to the isolation of the adducts [5–9].
Our group has studied the thermodynamics and
the kinetics of adduct formation between organ-
otin(IV)halide acceptors with donors, such as por-
phyrins and transition metal Schiff base complexes
[10–19].
Instruments
Light-absorption measurements in the visible re-
gion were made with
a Perkin-Elmer-UV–vis
spectrophotometer-Lambda 2, equipped with a Lauda-
ecoline-RE thermostat. FTIR spectra were run on a Shi-
madzu FTIR-8300 spectrophotometer. H NMR, 13C
1
NMR spectra were recorded on a Bruker Avance DPX-
250 spectrometer in DMSO-d6 solvent using tetram-
ethylsilane (TMS) as an internal standard. 119Sn NMR
spectra were recorded on a Bruker Avance DPX-400
spectrometer in the DMSO-d6 solvent. Elemental mi-
croanalyses (C.H.N.) were obtained by using a thermo
Finnigan-CHNSO analyzer.
Our interest in the tetraaza macrocy-
cle,
tmtaa
[(5,7,12,14-tetramethyldibenzo[b, i]
Synthesis
[1,4,8,11]tetraazacyclotetradecine)], is derived from
structural/chemical similarities with porphyrins
(Fig. 1), in particular with the facile complexation of
metal ions following deprotonation. The tmtaa Schiff
base has a saddle structure in which the four nitrogen
atoms lie in a plane, thereby creating a natural location
The Schiff bases were prepared according to the
method described in the literature [26] (Scheme 1),
yielding 60%. The IR, H NMR, 13C NMR, and the
1
UV–vis absorption spectra were in good agreement
with the published data.
˚
(cavity size ca. 1.9 A) for metal encapsulation [20].
In comparison with main group porphyrin and ph-
thalocyanine complexes, very little is known about the
other teteraaza macrocycles, such as tmtaa.
Molecular interactions of organotin(IV)halides with
a variety of uni- and bidentate nitrogen donor ligands
are studied [21]. Owing to the antitumor properties of
organotin(IV)halides, their interactions with biological
systems have been the subject of a number of investi-
gations [22–25].
The present work deals with the kinetics and
mechanism of the acceptor–donor interaction be-
tween RSnCl3 and R2SnCl2 (R = Ph, Bu, Me) with
tetraaza Schiff bases: (Me4-Bzo2[14]tetraeneN4)
(tmtaa), (Me4-4-CH3Bzo2[14]tetraeneN4) (Metmtaa),
(Me4-4-ClBzo2[14]tetraeneN4) (Cltmtaa) that [(Me4-
Synthesis of Diorganotin(IV)dichloride Complexes.
R2SnCl2 (R = Ph, Me, Bu) (0.05 mmol) was dissolved
in acetonitrile (5 mL) and added dropwise to tmtaa
Schiff base (0.05 mmol) in acetonitrile (10 mL) at
pH > 7 by adding some drops of NEt3, and the mix-
ture was stirred for 6 h at room temperature. During the
time, yellow Schiff base changed to purple. The change
in color was due to the interaction of R2SnCl2 with the
Schiff base. Addition of n-hexane precipitated a pur-
ple powdery product. The progress of the reaction was
monitored by UV–vis spectra. The tetraaza Schiff base
completely changed to the tin(IV) complexes, and the
mixture did not show any absorption bands related to
the free Schiff base. The results of the elemental anal-
yses for the diorganotin(IV)complexes formed from
the tetraaza Schiff base and R2SnCl2 (R = Ph, Me,
Bu), which were dried in the vacuum oven for 24 h at
75–80◦C, were consistent with [R2Sn(tmtaa)].
Bzo2[14]tetraeneN4)]
is
(5,7,12,14-tetramethyl-
dibenzo[b, i][1,4,8,11]tetraazacyclotetradecine) (tm-
taa) in acetonitrile as solvent. Some products of the
International Journal of Chemical Kinetics DOI 10.1002/kin

KINETIC INTERACTION BETWEEN ORGANOTIN(IV)CHLORIDES AND TETRAAZA SCHIFF BASES
249
NH2
No template
Ni template
NH2
O
O
N
N
N
N
N
Ni
N
H
+H+
+
1) HCl
2) 2NH4PF6
3) NEt3
H
N
N
H
N
H
N
N
2
H
N
1
Scheme 1 General procedure for synthesis of tmtaa and its derivatives.
[Me2Sn(tmtaa)]. Yield 54%, mp 190–191◦C. Anal.
Found/Calcd. C, 58.44/58.69; H, 5.71/5.75; N,
11.56/11.41%. 1H NMR (DMSO-d6, 250 MHz) (ppm):
0.94 (6H, s, JSn−H = 75 Hz, Sn-CH3), 1.70 (12H, s,
CH3), 4.12 (2H, s, CH), 6.52–6.85 (8H, m, aromatic).
13C NMR (DMSO-d6, 250 MHz) (ppm): 12.35 (Sn-
CH3), 38.44 (CH3), 95.29 (CH), 123.38–133.96 (aro-
matic carbons), 175.61 (CN). 119Sn NMR (DMSO-d6,
400 MHz) (ppm): −254. IR (KBr, cm−1): υ(C N),
1631. UV–vis (acetonitrile) (λmax, nm): 500, 318.
MHz) (ppm): −267. IR (KBr, cm−1): υ(C N), 1635.
UV–vis(acetonitrile) (λmax, nm): 486, 300(sh).
[Ph2Sn(tmtaa)]. Yield 42%, mp 198–199◦C. Anal.
Found/Calcd.: C, 66.84/66.37; H, 5.17/5.24; N,
1
9.37/9.10%. H NMR (DMSO-d6, 250 MHz) (ppm):
1.74 (12H, s, CH3), 4.16 (2H, s, CH), 6.47–7.71
(8H, m, aromatic), 7.45–7.76 (10H, m, Sn-C6H5).
13C NMR (DMSO-d6, 250 MHz) (ppm): 38.44
(CH3), 93.21 (CH), 123.38–139.76 (aromatic carbons),
175.47 (CN). 119Sn NMR (DMSO-d6, 400 MHz)
(ppm): −246. IR (KBr, cm−1): υ(C N), 1635. UV–
vis(acetonitrile) (λmax, nm): 498, 318.
[Bu2Sn(tmtaa)]. Yield 42%, mp 197◦C–199◦C. Anal.
Found/Calcd. C, 62.02/61.98; H, 7.68/7.97; N,
1
9.46/9.64%. H NMR (DMSO-d6, 250 MHz) (ppm):
0.91 (6H, t, J = 7 Hz, CH3), 1.32–1.75 (12H, m, Sn-
CH2CH2CH2), 1.76 (12H, s, CH3), 4.14 (2H, s, CH),
6.47–7.71 (8H, m, aromatic). 13C NMR (DMSO-d6,
250 MHz)(ppm): 15.42, 19.86, 28.76, 30.25 (Sn-Bu),
38.44 (CH3), 93.21 (CH), 123.38–133.96 (aromatic
carbons), 175.47 (CN). 119Sn NMR (DMSO-d6, 400
Kinetic Studies
Kinetic data were determined spectrophotometrically.
In all cases (runs from 10–40
dure involves adding a sample of a given acceptor to
a solution containing the tetraaza Schiff base ligand at
0.1◦C), the proce-
International Journal of Chemical Kinetics DOI 10.1002/kin

250
ASADI
pH > 7. Light-absorption measurements in the UV–
vis region were made with a Perkin-Elmer-UV–vis
spectrophotometer-Lambda 2, equipped with a Lauda-
ecoline-RE thermostat. The kinetics was followed at
a predetermined wavelength, where the difference in
absorption between the substrate and the adduct was
the largest. The kinetics was followed under pseudo-
first-order conditions for the acceptor concentrations;
the substrate concentration was kept constant at about
1.4 × 10−5 M, and the excess concentration of each
acceptor varied in the range 10–600-fold in excess. The
temperature was controlled in a thermostated cell com-
partment at 10–40 0.1◦C, and 10-mm quartz cells
were used. The pseudo-first-order constants were cal-
culated by fitting the data to ln[(At − A )/(A0 − A )]
R
R
X
X
Sn
N
N
N
N
Me
Me
Me
Me
Figure 2 Proposed structure of [R2Sn(X-tmtaa)] X = H,
Cl, Me.
In 1H NMR spectra of [Me2Sn(tmtaa)], protons of two
methyl groups attached to the Sn also appear as one
sharp singlet with a high field shift, with respect to the
corresponding parent Me2SnCl2 signal. The 13C NMR
spectra chemical shift assignments for carbon atoms in
different environment are summarized in the Experi-
mental section; again a single high field resonance in
the case of [Me2Sn(tmtaa)] confirms the equivalence
of the methyl groups attached to the metal.
Holecˆek and coworkers’ results show that in the di-
and triorganotin complexes, the 119Sn NMR spectra
can be used as an indicator of the coordination number
of the tin atom. In the range of +200 to −60, −90
to −4190, −210 to −400, and −440 to −540 ppm,
the coordination numbers of the tin are four, five, six,
and seven, respectively [27–30]. The complexes in the
present investigation exhibit the 119Sn spectra in the
range −240 to −270 ppm, suggesting that the tin atoms
are six coordinate.
∞
∞
= −kobst (where At = absorbance at time t, A0 =
absorbance at t = 0, and A∞ = absorbance at t = ∞)
by means of a linear least-squares computer pro-
gram. At was determined after each 10–60 s de-
pending on the system. The second-order rate con-
stants k2 were obtained from the slope of the lin-
ear plots of kobs versus [A] (acceptor concentration).
The activation enthalpy and the activation entropy
parameters, ꢀHꢀ= and ꢀSꢀ= (see Table III later in
the paper) were obtained by fitting the data to lin-
ear least-squares computer programs of the Eyring
equation (1):
ln(k2/T ) = −ꢀH#/RT + ꢀS#/R + 23.8 (1)
RESULTS AND DISCUSSION
NMR Spectra
The general approach involves deprotonation of
H2tmtaa and the subsequent reaction of the tmtaa2−
dianion with R2SnCl2.
ELEMENTAL ANALYSIS
Elemental analyses of these separately synthesized
products are in good agreement with the proposed
adducts formed at the end of the kinetic runs.
R2SnCl2
H2tmtaa P−H→≥7 tmtaa2− −→ R2Sn(tmtaa) (2)
where R = Me, Bu, Ph.
Kinetic Study
The compounds with microanalytical and spectro-
scopic data are listed in the Experimental section. The
spectroscopic data are consistent with a proposed struc-
ture (solution) in which the SnR2 unit is bonded to the
four nitrogen atoms, resulting in a six-coordinate ge-
ometry around the metal center. Such an arrangement,
depicted in Fig. 2 with the ligand in its saddle confor-
mation and the two substituent groups(R) mutually cis,
has been reported.
Tables I–III show the rate constants and the activation
parameters for the interaction of acceptors with the
tetraaza Schiff base in acetonitrile as a solvent at vari-
ous temperatures. Although most of the kinetic studies
that have been published were carried out in interfering
(i.e., coordinating) solvents, it is necessary to investi-
gate the nature of this interference before the mecha-
nistic assignment is secured [31]. Plots of kobs versus
[A] exhibit an almost zero intercept (Fig. 3). This indi-
cates that solvation of the Schiff base in acetonitrile is
negligible. The rate law of Eq. (3) is compatible with
In the 1H NMR spectra of the diorgan-
otin(IV)complexes, both the aromatic ring and the CH,
CH3 protons of the ligand appear as a sharp singlet.
International Journal of Chemical Kinetics DOI 10.1002/kin

KINETIC INTERACTION BETWEEN ORGANOTIN(IV)CHLORIDES AND TETRAAZA SCHIFF BASES
251
Table I k2 (M−1s−1) Rate Constants for the Reaction of Organotinchlorides with tmtaa, [tmtaa] = 1.4 × 10−5 M, in
CH3CN at Different Temperatures
Temperature (◦C)
Organotin Chloride
10
20
30
40
PhSnCl3
100.9 (6.8)
69.8 (3.6)
21.7 (0.7)
9.3 (0.4)
110.4 (9.7)
79.1 (3.9)
27.4 (2.0)
11.3 (0.5)
2.5 (0.1)
120.8 (6.9)
90.0 (4.0)
31.8 (1.5)
14.1 (0.5)
2.8 (0.1)
129.4 (6.3)
105.9 (3.6)
36.1 (2.1)
17.1 (0.7)
3.2 (0.1)
MeSnCl3
Ph2SnCl2
Me2SnCl2
Bu2SnCl2
2.3 (0.1)
Numbers in parentheses are the standard deviations of k2.
36
32
28
10
20
30
40
24
k
20
16
12
8
4
4
8
12
16
20
24
[A]/M
Figure 3 Plots of kobs vs. Bu2SnCl2 molar concentrations [A] at different temperatures.
the adduct formation according to Eq. (4).
The k2 values are obtained from the slope of the
linear plots of kobs versus the acceptor concentration
[A] (Fig. 3).
The isosbestic points in the absorption spectra
(Fig. 4) suggest that only one reaction is in progress
(Eq. (4)); it indicates that different products was not
produced. Also the electronic spectra of the adducts
formed in the kinetic study were the same as the elec-
tronic spectra of the separately synthesized diorgan-
otin(IV) complexes (Fig. 5).
kobs = k2[A]
X − tmtaa + R2SnCl2/(RSnCl3)
→ [R2Sn/(RSnCl).X − tmtaa]
(3)
(4)
where X = H, Cl, Me and R = Me, Bu, Ph.
Table II k2 (M−1s−1) Rate Constants for the Reaction
of Ph2SnCl2 with Tetraaza ligands [ligand] = 1.4 ×
10−5M, in CH3CN at Different Temperatures
The activation parameters ꢀH# and ꢀS# were
obtained from the standard linear Eyring plots of
ln(k2/T ) versus 1/T with a good correlation of 0.97–
0.99 (Fig. 6).
The results show that there is a linear rate depen-
dence on the concentration of the acceptor. Typical
plots of kobs versus Bu2SnCl2 molar concentrations of
the tmtaa ligand at different temperatures are shown in
Fig. 3.
Temperature (◦C)
10
20
30
40
Metmtaa 27.6 (0.9) 34.0 (1.5) 41.1 (1.6) 50.9 (2.5)
tmtaa
Cltmtaa
21.7 (0.7) 27.4 (2.0) 31.8 (1.5) 36.1 (2.1)
16.4 (0.6) 22.6 (1.0) 28.9 (1.2) 32.7 (1.3)
Numbers in parentheses are the standard deviations of k2.
International Journal of Chemical Kinetics DOI 10.1002/kin

252
ASADI
Table III Activation Parameters ꢀH#, ꢀS#, and ꢀG# for the Reaction of Organotinchlorides with Schiff Bases in
CH3CN
Adduct
ꢀH#(kJ mol−1
)
ꢀS#(J K−1 mol−1
)
ꢀG#(kJ mol−1)a
PhSnCl3. tmtaa
3.7 (0.2)
7.7 (0.7)
12.4 (0.4)
9.9 (1.0)
14.4 (1.6)
12.7 (0.4)
3.7 (0.2)
−193.3 (0.6)
−182.5 (2.2)
−173.4 (1.4)
−184.1 (3.5)
−170.3 (5.4)
−181.6 (1.4)
−225.0 (0.8)
64.2 (0.3)
64.8 (0.9)
66.7 (0.6)
67.5 (1.5)
67.7 (2.4)
69.5 (0.6)
74.1 (0.3)
MeSnCl3. tmtaa
Ph2SnCl2. Metmtaa
Ph2SnCl2. tmtaa
Ph2SnCl2.Cltmtaa
Me2SnCl2.tmtaa
Bu2SnCl2.tmtaa
Numbers in parentheses are the standard deviations.
aCalculated from ꢀG# = ꢀH# − T ꢀS# at T = 313 K.
1.2
1
0.8
0.6
0.4
0.2
0
270
295
320
345
370
395
Wavelength/nm
Figure 4 Absorption spectra of tmtaa with Bu2SnCl2 at 30◦C in CH3CN with isosbestic points. Time interval = 30 s.
Me2SnCl2, and Bu2SnCl2 and indicates that replac-
ing the methyl group by a more bulky butyl group on
an organotin(IV) compound weakens interactions. The
butyl group can affect the interaction in two ways: (1)
a more bulky butyl group makes adduct formation un-
favorable because of its greater steric hindrance than a
methyl group [31], and (2) butyl groups, though, have
better electron-releasing properties to reduce the ac-
ceptor strength of a diorganotin(IV) Lewis acid and to
decrease its interaction with Schiff bases.
Donor Properties of Ligands
The existence of methyl ( CH3) groups as electron-
releasing groups makes the (Me4-4-CH3Bzo2[14]
tetraeneN4) ligand a better donor compared with (Me4-
Bzo2[14]tetraeneN4), and also electron-withdrawing
groups, such as chloride ( Cl), reduce the donor prop-
erty of (Me4-4-ClBzo2[14]tetraeneN4); thus the for-
mation constants decrease according to the following
sequence: Metmtaa > tmtaa > Cltmtaa.
Acceptor Properties of Organotin Chlorides
Elucidation of the Mechanism
Comparing the k2 values, the following trend of acid-
ity for the acceptors’ use was assessed: PhSnCl3 >
MeSnCl3 > Ph2SnCl2 > Me2SnCl2 > Bu2SnCl2.
It is clear that acceptors with lower steric hin-
drance were better Lewis acids, such as PhSnCl3 and
MeSnCl3. The electron-withdrawing group (Ph ) on
the tin center makes PhSnCl3 a stronger acceptor than
MeSnCl3. This trend is also observed for Ph2SnCl2,
Reaction rates almost always increase with tempera-
ture. The expression of the temperature dependence
is always given for the rate constant, rather than the
rate.
The activation parameters bring out several features:
The quite small enthalpy represents very rapid reaction.
The values of ꢀH# most simply relate to the differ-
ences in bond enthalpies between the transition state
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KINETIC INTERACTION BETWEEN ORGANOTIN(IV)CHLORIDES AND TETRAAZA SCHIFF BASES
253
Figure 5 Electronic spectra of tmtaa ligand (1.4 × 10−5 M) (1), the end point of titration of ligand with Me2SnCl2 (2), and
separately synthesized [Me2Sn(tmtaa)] adduct (7.6 × 10−4 M) (3) in acetonitrile.
0
PhSnCl .tmtaa
3
MeSnCl .tmtaa
3
Ph SnCl .Metmtaa
2
2
T
Ph SnCl .tmtaa
k
2
2
Ph SnCl .Cltmtaa
2
2
Me SnCl .tmtaa
2
2
Bu SnCl .tmtaa
2
2
3.1
3.2
3.3
3.4
3.5
3.6
1031/T(K
)
Figure 6 Eyring plots for adduct formation of Schiff bases with different acceptors in acetonitrile.
ꢀS#, and the low ꢀH# values suggest an associative
(A) mechanism.
and the reactants. In solution reactions, it is tempting
to assign the value of ꢀH# for a unimolecular reaction
to the bond dissociation enthalpy of the bond being
cleaved in the activated process. The relationship may
be true in certain cases, but differences in the solvation
energies of the reactants and transition state cannot
necessarily be ignored, particularly for species bearing
ionic charges.
CONCLUSION
The results of this work can be summarized as follows:
The activation entropy associated with k2 is partic-
ularly large, and negative, thus ꢀS# reflects the loss
of entropy from the union of the two reaction partners
into a single transition state.
The k2 values for the ligands entry show high span
(more than 10-fold); therefore, they suggest the depen-
dence on the nature of the acceptor. Also the linear
plots of kobs versus [A], the large negative values of
1. We measured the relative donor properties
(Lewis basicity) of different Schiff bases
toward organotin(IV)chlorides. In a kinetic
study, this trend of basicity was obtained
due to electronic effects: Me4-4-CH3 Bzo2[14]
tetraeneN4 > Me4-Bzo2[14]tetraeneN4 > Me4-
4-ClBzo2[14]tetraeneN4.
International Journal of Chemical Kinetics DOI 10.1002/kin

254
ASADI
2. The formation constants for a given donor (Schiff
base) change according to the following trend
for organotin(IV)compounds due to the elec-
tronic and steric effects: PhSnCl3 > MeSnCl3 >
Ph2SnCl2 > Me2SnCl2 > Bu2SnCl2.
3. The kinetics and mechanism of adduct forma-
tion were studied. The high span of k2 values,
the linear plots of kobs versus [A], the large neg-
ative values of ꢀS#, and the low values of ꢀH#
suggest an associative (A) mechanism.
12. Asadi, M.; Zabardasti, A.; Ghasemi, J. Bull Chem Soc
Jpn 2002, 75, 1137–1141.
13. Asadi, M.; Zabardasti, A.; Kakanejadifard, J. Hetro-
cyclic Chem 2006, 43, 1–4.
14. Asadi, M.; Zabardasti, A. J Chem Res (s) 2002, 611–
613.
15. Asadi, M.; AeinJamshid, Kh.; Kyanfar, A. H. Trans Met
Chem 2007, 32, 822–827.
16. Asadi, M.; AeinJamshid, Kh.; Kyanfar, A. H. J Coor
Chem 2008, 61(7), 1115–1126.
17. Asadi, M.; AeinJamshid, Kh.; Kyanfar, A. H. Synth Re-
act Inorg Met-Org Nano-Met Chem 2007, 37, 77–83.
18. Asadi, M.; AeinJamshid, Kh.; Kyanfar, A. H. Inorg
Chim Acta 2007, 360, 1725–1730.
BIBLIOGRAPHY
19. Asadi, M.; Asadi, Z.; Mosallanezhad, F. Int J Chem
Kinet 2010, 42, 499–507.
1. Yin, H. D.; Chen, S. W. J Organomet Chem 2006, 691,
3103–3108.
20. Cotton, F. A.; Czuchajowska, J. Polyhedron, 1990,
9(21), 2553–2566.
2. Nath, M.; Singh, H.; Eng, G.; Song, X. J Organomet
Chem 2008, 693, 2541–2550.
3. Nath, M.; Saini, P. K.; Eng, G.; Song, X. J Organomet
Chem 2008, 693, 2271–2278.
4. Yu, H. X.; Ma, J. F.; Xu, G. H.; Li, S. L.; Yang, J.;
Liu, Y. Y.; Cheng, Y. X. J Organomet Chem 2006, 691,
3531–3539.
5. Clarke, B.; Cunningham, D.; Gallagher, J. F.; Higgins,
T.; McArdel, P.; McGinley, J.; Cholchuin, M. N.;
Sheerin, D. J Chem Soc, Dalton Trans 1994, 2473–2482.
6. Cunningham, D.; Fitzgerald, J.; Little, M. J Chem Soc,
Dalton Trans 1987, 2261–2266.
21. Yoder, C. H.; Mokrynk, D.; Spencer, J. N.; Coly, S. M.;
Otler, R. E.; Haines, A.; Grushow, L. J Organometallics
1987, 6, 1679–1684.
22. Shoukry, M. M. Talanta 1996, 43, 177–183.
23. MaManus, J.; Cunningham, D.; Hynes, M. J.
J Organomet Chem 1994, 468, 87–92.
24. Barbieri, R.; Silvestri, A.; Giuliani, A. M.; Piro, V.;
Disimon, F.; Madonia, J. J Chem Soc, Dalton Trans
1992, 585–590.
25. Crowe, A. J.; Smith, P. J.; Cordin, C. J.; Parge, H. E.;
Smith, F. E. Cancer Lett 1984, 24, 45–48.
26. Goedken, V. L.; Molin-Case, J. Y.; Whang, A. J Chem
Soc, Chem Commun 1973, 10, 337–338.
27. Holecek, J.; Nadvornik, M.; Handlir, K.; Lycka, A.
J Organomet Chem 1983, 241, 177–184.
7. Clarke, N.; Cunningham, D.; Higgins, T.; McArdel, P.;
McGinley, J.; O’Gara, M. J Organomet Chem 1994, 469,
33–40.
8. Clarke, B.; Clarke, N.; Cunningham, D.; Higgins, T.;
McArdel, P.; Cholchuin, M. N.; O’Gara, M. J Organomet
Chem 1998, 559, 55–64.
9. Cunningham, D.; McGinley, J. J Chem Soc, Dalton
Trans 1992, 1387–1391.
10. Asadi, M.; Zabardasti, A.; Karimivand, V.; Ghasemi,
J. Polyhedron 2002, 21, 1255–1260.
11. Asadi, M.; Zabardasti, A.; Ghasemi, J. Polyhedron 2002,
21, 683–687.
28. Holecek, J.; Nadvornik, M.; Handlir, K.; Lycka,
A. J Organomet Chem 1983, 258, 147–153.
29. Nadvornik, M.; Holecek, J.; Handlir, K.; Lycka, A.
J Organomet Chem 1984, 275, 43–51.
30. Lycka, A.; Holecek, J.; Nadvornik, M.; Handlir, K.
J Organomet Chem 1985, 280, 323–329.
31. Tobe, M. L.; Burgess, J. In Inorganic Reaction Mech-
anism; Addison-Wesley Longman: Harlow: UK, 1999;
Ch. 3.
International Journal of Chemical Kinetics DOI 10.1002/kin