Complex formation of magnesium(II) with octaaryltetraazaporphyrins in pyridine

Article abstract of DOI:10.1023/A:1013105704971

Complex formation of magnesium with octaphenyltetraazaporphyrin, octakis[p-(chloromethyl)-phenyl] tetraazaporphyrin, and octakis[p-(dodecylsulfamoyl)phenyl]tetraazaporphyrin from corresponding ligands and magnesium acetate in pyridine and pyridine-diethylamine was studied. Increase in the basicity of the medium favors a much faster reaction. Some suggestions concerning the mechanism of the reaction were made.

Full text of DOI:10.1023/A:1013105704971

Russian Journal of General Chemistry, Vol. 71, No. 7, 2001, pp. 1058 1065. Translated from Zhurnal Obshchei Khimii, Vol. 71, No. 7, 2001,
pp. 1124 1131.
Original Russian Text Copyright
2001 by Khelevina, Rumyantseva, Antina, Lebedeva.
Complex Formation of Magnesium(II)
with Octaaryltetraazaporphyrins in Pyridine
O. G. Khelevina, S. V. Rumyantseva, E. V. Antina, and N. Sh. Lebedeva
Ivanovo State University of Chemical Engineering, Ivanovo, Russia
Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, Russia
Received December 14, 1999
Abstract Complex formation of magnesium with octaphenyltetraazaporphyrin, octakis[p-(chloromethyl)-
phenyl]tetraazaporphyrin, and octakis[p-(dodecylsulfamoyl)phenyl]tetraazaporphyrin from corresponding
ligands and magnesium acetate in pyridine and pyridine diethylamine was studied. Increase in the basicity of
the medium favors a much faster reaction. Some suggestions concerning the mechanism of the reaction
were made.
Tetraazaporphyrins react with metal salts, forming
Solv
complexes according to Eq. (1) [1, 2].
Solv
OAc
M
H TAP + [MX (Solv) 2]
AcO
2
2
n
N
N
N
(
Solv) MTAP + 2HX + (n
2
m)Solv. (1)
H
N
m
N
H
N
N
Here H TAP is tetraazaporphyrin ligand, MTAP is
2
Solv
Solv
metal complex of the tetraazaporphyrin, Solv is sol-
vent, [MX (Solv) 2] is solvation complex of the
2
n
metal salt. Depending on the metal nature, solvent
molecules may remain bound with the central metal
atom as extra ligands.
N
N
N
N
M
N
N
N
N
+
+
2HSolv +2AcO + 4Solv.
(2)
Complex formation of metal acetates with tetra-
azaporphyrines in pyridine most frequently occurs by
the bimolecular mechanism SNE2 [3]. Pyridine
molecules in the stage of activation of the system
2+
phyrins [H TAP(C H R) ] and Mg ions in pyridine
and pyridine diethylamine.
2
6
4
8
H TAP salt effect solvation of endocyclic protons and
R
R
2
force them out of the macroring plane. The reaction
center acquires additional charge and thus gets more
delocalized. The metal cation favors this process.
Bond formation between the cation and tertiary nitro-
R
R
N
R
R
N
NH
N
N
N
HN
gen atoms of H TAP almost compensates for the
2
N
energy consumption for M Solv bond cleavage
[
scheme (2)].
R
R
H TAP(C H R)
8
Proceeding with our works [4 6], we have studied
2
6
4
complex formation between octaaryltetraazapor-
R = H, CH Cl, SO NHC H .
2
2
12 25
Solv
Complex formation of H TAP(C H R) with
N
N
2
6
4
8
N
H
H
magnesium acetate was performed with a large excess
of the salt, i.e. under pseudo-first-order reaction con-
ditions. Actually, the formation of MgTAP(C H R)
[
M(OAc) Solv ] +
N
2
4
N
N
N
6
4
8
Solv
1
070-3632/01/7107-1058$25.00 2001 MAIK Nauka/Interperiodica

COMPLEX FORMATION OF MAGNESIUM(II)
1059
log kapp
(a)
3
(a)
4
4
.8
.6
0
.12
.08
4
3
2
0
0
4
4
.4
.2
2
1
1
.04
0
4
.0
2
.8
2.9
3.0
3.1
3.2
(b)
1
0
20
30 40 50
60
(b)
3
4
4
4
.6
.4
.2
2
4
0
.20
3
0
0
.15
.10
1
4
.0
3.8
.6
3.4
.2
2
1
3
0
.05
0
3
2.8
2.9
3.0
3.1
3.2
c)
10
20
30
min
(
,
4
0
Fig. 1. Plot of log c
/c
vs.
H TAP(C H R) H TAP(C H R)
2
6
4
8
2
6
4
8
4
.3
4.1
.9
.7
time for complex formation (a) of H TAP(Ph) with
Mg(OAc) in pyridine diethylamine at (1) 303, (2) 313,
2
8
3
2
3
and (3) 323 K [c
1.36 10 M)] and (b) of
-p) with Mg(OAc) in
2
1
Mg(OAc)2
H TAP(C H SO NHC
H
2
6
4
2
12 25
8
2
3
pyridine at (1) 313, (2) 323, and (3) 333 K [c
Mg(OAc)2
3
0
.89 10 M].
3
is a first-order reaction in H TAP(C H R) concentra-
2
6
4
8
3
.5
2
tion, which is evidenced by linear dependences of
.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2
log (c0
/c ) on reaction time
log c0
H TAP(C H R) H TAP(C H R)
8
2
6
4
8
2
6
4
Mg(OAc)2
0
(
Fig. 1). Therefore, the apparent and true rate con-
stants can be calculated by Eqs. (3) and (4):
Fig. 2. Plot of log k
vs. log c
) for
Mg(OAc)
2
app
complex formation (a) with H TAP(Ph) in pyridine di-
ethylamine at (1) 323, (2) 313, (3) 303, and (4) 298 K;
2
8
dc
/d = kapp
c
,
(3)
(4)
MgTAP(C H R)
H TAP(C H R)8
6
4
8
2
6 4
kapp = k c n
(b) with H TAP(C H SO NHC -p) in pyridine at
H
.
2
6
4
2
12 25
8
Mg(OAc)
2
(
1) 333, (2) 323, (3) 313, and (4) 298 K); and (c) with
H TAP(C H CH Cl-p) in pyridine at (1) 343, (2) 333,
Here kapp is the apparent rate constant, k is the true
rate constant, and n is the reaction order in mag-
nesium acetate.
2
6
4
2
8
(
3) 323, and (4) 298 K.
octakis[p-(dodecylsulfamoyl)phenyl]tetraazaporphy-
rin formation are almost independent on salt concen-
tration. Figure 2 depicts the log kapp log cMg(OAc)2
dependences for complex formation of octaphenyl-
tetraazaporphyrin and octakis[p-(dodecylsulfamoyl)-
phenyl]tetraazaporphyrin in pyridine diethylamine
and pyridine, respectively. The reaction order in
Tables 1 and 2 list the kinetic parameters of
complex formation of octaaryltetraazaporphyrins
with magnesium acetate in pyridine and pyridine
diethylamine.
The experimental data showed that the rate con-
stants of Mg octaphenyltetraazaporphyrin and Mg
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 7 2001

1060
KHELEVINA et al.
Table 1. Kinetic parameters of Mg octaaryltetraazaporphyrin formation (c 0
0.89 10 3 M)
Mg(OAc)
2
kapp 10 , s 1
4
E, kJ/mol
S , J mol 1 K 1
Compound
T, K
Pyridine diethylamine (cNHEt2 1.36 M)
H TAP(Ph)8
(
298
303
0.19a
0.25 0.02
0.42 0.05
0.66 0.03
39 2
216 5
2
c0 1.23 10 5 M)
3
3
13
23
Pyridine
a
H TAP(Ph)8
(
298
333
1.00 10 2
0.20 0.05
0.44 0.05
0.85 0.06
71 3
49 2
130 6
193 7
2
c0 1.23 10 5 M)
3
3
43
53
H TAP(C H SO NHC H -n)
8
298
313
0.26a
0.61 0.02
1.30 0.03
1.92 0.02
2
6
4
2
12 23
5
(c0 1.27 10 M)
3
3
23
33
a
Calculated by the Arrhenius equation.
Table 2. Kinetic parameters of Mg octakis[p-(chloromethyl)phenyl]tetraazaporphyrin formation in pyridine
0
4
(c
0.524 10 M)
H TAP(C H CH Cl-n)
2
6
4
2
8
kapp 10 , s 1
3
E, kJ/mol
S , J mol 1 K 1
cMg(OAc)2, M
T, K
6
1
2
5
8
1
10 5
298
0.038a
20 4
272 7
323
333
343
0.071 0.002
0.090 0.004
0.112 0.004
0.038a
0.070 0.001
0.091 0.005
0.110 0.004
0.038a
0.073 0.002
0.090 0.005
0.112 0.004
0.038a
0.07 0.002
0.09 0.006
0.11 0.004
0.065a
.3 10 4
.9 10 4
.9 10 4
.9 10 4
.18 10 3
298
20 4
21 4
20 3
19 1
17 1
272 7
272 6
272 8
268 4
265 4
323
333
343
298
323
333
343
298
323
333
343
298
323
333
343
0.121 0.004
0.152 0.004
0.180 0.005
0.087a
298
323
333
343
0.160 0.002
0.191 0.004
0.233 0.004
a
Calculated by the Arrhenius equation.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 7 2001

COMPLEX FORMATION OF MAGNESIUM(II)
magnesium acetate n, measured by the slope ratios of
1061
the above dependences, proved to be zero. Apparently,
with these porphyrins, the limiting stage of the com-
plex formation with Mg occurs by a mechanism
similar to that established for complex formation of
A
2
2
+
2+
2+
octaphenyltetraazaporphyrin with Zn , Cu , Cd ,
3
1
2
+
2+
Co , and Ni in pyridine [7]. According to this
mechanism, coordination in tetraazaporphyrins can
involve both internal and external meso-nitrogen
atoms to form with metal acetate unstable intermedi-
ate complexes of the amine type [Eq. (5)]:
4
00
639 700
, nm
H TAP(C H R) + [M(OAc)2Solv4]
2
6
4
8
H TAP(C H R) [M(OAc)2Solv3] + Solv. (5)
2
6
4
8
Fig. 3. Electronic absorption spectra in pyridine of
(
(
1)
H TAP(Ph)
(freshly
prepared
pyridinium salt
solution),
of
2
8
Such intermediate complexes can convert into
MTAP(C H R) via migration of the metal cation
2) MgTAP(Ph) , and (3)
8
6
4
8
H TAP(Ph) .
2
8
from the meso-nitrogen atom to the reaction center
scheme (6)]:
[
phenyltetraazaporphyrin by pyridine is confirmed by
the following fact: The splitting of the Q band in the
electronic absorption spectrum of octaphenyltetra-
azaporphyrin in pyridine is 80 cm 1 smaller than in
the spectrum in chlorobenzene (solvatochromic effect).
On prolonged standing of the pyridine solution of
octaphenyltetraazaporphyrin at room temperature or
on its boiling for some hours a pyridinium salt or an
acid base complex [Eq. (7)] are formed [7].
Solv
AcO
N
N
N
Solv
H
N
N
H
N
Solv
Solv
M
N
N
Solv
AcO
N
N
N
N M
N
+
2
H TAP(Ph)8 + 2PyH
2(PyH ) TAP(Ph) . (7)
2 8
N
2
N
N
This reaction has first been observed by Whalley
10] for tetraazaporphyrin, its alkyl derivatives, and
+
2H +S olv+ 2AcO + 3Solv.
(6)
[
phthalocyanine. The referee showed that such
complexes with the mentioned tetraazaporphyrins can
form only photochemically. With more acidic tetra-
azaporphyrins (tetrabromotetraazaporphyrin, tetra-
chlorotetraazaporphyrin), the formation of the pyri-
dinium salt in pyridine is complete at room tempe-
rature within 40 60 min [11]. The changes in the elec-
tronic absorption spectra of tetraazaporphyrins, that
accompany acid base complex formation, are similar
to those observed on addition of metal ions, implying
removal of protons from the reaction center with
increase in the ligand symmetry from D2h to D4h
Probably, the intermediate amine complex is
formed not only by donor acceptor interaction, but
also by hydrophobic interaction between
H TAP(C H R) and ligand environment of the metal.
2
6
4
8
Such interaction of meso-nitrogen atoms with
metal cations has been found in the Ni(II) complex of
tetrakis(S,S-dibutyltin) octathiolatotetraazaporphyrin
[
8]. The formation of the amine complex is favored by
electron-donor substituents in pyrrole rings of the
tetraazaporphyrin macroring, which increase the elec-
tron density on the meso-nirogen atoms [3], as well
as by strong solvation of the reaction center, which
hinders axial attack by the metal [3].
(
Fig. 3). Studies on acid base interactions of tetraaza-
The stability constants of first acidic forms (proto-
nated by meso-nitrogens) of octaphenyltetraazapor-
porphyrins with various bases in chlorobenzene
showed that the complexes formed differ in the degree
of charge transfer from the tetraazaporphyrin to the
donor center of the base, which depends on the elec-
tronic and geometric structure of the tetraazaporphyrin
and base, as well as on the features of solvation of the
resulting acid base forms [12] [scheme (8)].
phyrin and tetraazaporphyrin (pK 1 and 0.15, respec-
1
tively) show that phenyl radicals actually increase the
basicity of the macroring by increasing the electron
density on meso-nitrogen atoms by the +I effect [9].
The strong solvation of the reaction center in octa-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 7 2001

1062
KHELEVINA et al.
(b)
(a)
TG
TG
T, K
5
0
Weight,
mg
5
23
5
23
473
423
373
1
:2 1:1
1
:2 1:1
DTG
4
4
73
23
DTG
DTA
25
25
DTA
3
3
73
23
Td
3
23
T
T
Td
20
40 60 80
20 40 60 80
,
min
Fig. 4. Thermoanalytical curves for the crystal solvates (a) of H TAP(Ph) with pyridine and (b) of MgTAP(Ph) with
2
8
8
pyridine.
H TAP + B
B H TAP H B
H complex
In the binary mixture pyridine diethylamine the
Mg octaphenyltetraazaporphyrin complex is formed
2
2
0 times faster than in pyridine (Table 1). Diethyl-
+
BH+ TAP2 H B
+
B H TAP H B
ion ion associate
amine, being a stronger base than pyridine, accelerates
the reaction by enhancing polarization of N H bonds,
ion ion associate
TAP //2BH+
solvent-separated
ion pair
2
TAP2 + 2BH . (8)
+
which favors formation of the TAP(Ph)2 anion and
8
dianion
thus the transition state of the reaction.
Earlier Stuzhin et al. [4] studied complex forma-
tion of magnesium with unsubstituted tetraazapor-
phyrin in pyridine. Comparison of the rate constants
of complex formation of tetraazaporphyrin and octa-
phenyltetraazaporphyrin in pyridine showed that octa-
phenyltetraazaporphyrin coordinates with Mg ions 2
orders of magnitude faster than tetraazaporphyrin
The high thermal stability of octaphenyltetraazapor-
phyrin allowed us to perform a thermogravimetric
investigation of the crystal solvate of octaphenyltetra-
azaporphyrin with pyridine in the range 15 150 C,
where decomposition of the compound is excluded.
Analysis of the thermoanalytical curve (Fig. 4)
shows that octaphenyltetraazaporphyrin forms with
pyridine an H TAP(Ph) 2 PyH complex which is
2
98
10 and 9.6 10 9 s , respectively, at c
6
1
0
(
3
k
app
Mg(OAc)
2
4
10 M). It is known [3] that the rate of coordina-
2
8
tion of tetraazaporphyrins with metal ions in basic
solvents is controlled by N H bond cleavage, and
electron-donor substituents (such as phenyl) should
decelerate the reaction. This is the case in complex
stable in crystal solvate up to 68 C. The enthalpy of
the decomposition of the complex, accompanied by
evolution of gaseous pyridine, was estimated ( H
4
1.2 0.4 kJ/mol). The low acidity of octaphenyltetra-
2
+
formation of octaphenyltetraazaporphyrin with Cu ,
azaporphyrin (pKa1 13.79 in DMF [9]), the low di-
electric constant of pyridine ( 12.3 [13]), as well as
the energetic characteristics and the composition of
the complex suggest that the pyridinium salt of
octaphenyltetraazaporphyrin is an H complex like
2
+
2+
2+
2+
Co , Zn , Cd , and Ni ions [3]. The first coordin-
ation sphere of Mg2 in pyridine is unlike the coordi-
nation spheres of transition metal ions and is formed
by six pyridine molecules, and anions reside in the
+
second coordination sphere: [Mg(PyH) ](OAc) [4].
[
HPy H TAP(Ph)8 H PyH] [12] whose bonds are
6
2
This is the reason why tetraazaporphine coordinates
close in nature to donor acceptor bonds, as evidenced
by the H value. The pyridinium salt of octaphenyl-
tetraazaporphyrin is insusceptible to complex forma-
tion, since its reaction center is blocked by pyridine
molecules.
5
with Mg(II) slower by a factor of 10 than with Zn(II)
or Cd(II). The higher rate of coordination of octa-
phenyltetraazaporphyrin with Mg(II) can be ex-
plained by that the reaction here occurs by a mono-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 7 2001

COMPLEX FORMATION OF MAGNESIUM(II)
1063
Weight,
kg
(a)
(b)
T, C
1000
TG
1
00
100
1000
TG
DTG
800
8
00
7
5
75
DTG
Tm
6
4
00
00
6
00
5
0
50
Tc
Tc
Tm
4
2
00
00
To
DTA
2
5
25
DTA
200
T
T
To
30 60 90 120
30
60 90 120
,
min
Fig. 5. Thermoanalytical curves of thermooxidative decomposition of (a) H TAP(Ph) and (b) MgTAP(Ph) .
2
8
molecular mechanism, where the solvation shell of
Mg in the intermediate anionic complex is already
atom, reacts with magnesium acetate by a bimolecular
mechanism, like with Mg tetraazaporphyrin complex
2
+
strongly rearranged and thus weaker affects the limit- formation [4] (Fig. 2).
ing stage of the reaction.
The above results allowed us to rank the octaaryl
tetraazaporphyrins studied by their reactivity toward
magnesium acetate in pyridine as follows:
Introduction in phenyl radicals of octaphenyltetra-
azaporphyrin of the electron acceptor dodecylsul-
famoyl groups reduces the electron density on meso-
nitrogen atoms and thus unfavors the monomolecular
limiting stage. However, this mechanism is still
operative with the sulfamoyl derivative, probably,
because of the strong solvation of the reaction center;
therewith, autosolvation may occur due to the pre-
sence of C H groups (formation of quasi-solva-
tion shells). The same effect has been observed with
the Zn bis(octadecylamino)methyltetrabenzoporphine
complex formation [14]. The rate constants of com-
plex formation of the sulfamoyl derivative with
H TAP(Ph)8
<
H TAP(C H CH Cl-p)
<
2
2
6
4
2
8
H TAP(C H SO NHC H -p) .
2
6
4
2
12 25
8
We performed a thermogravimetric study of ther-
mooxidative decomposition of octaphenyltetraazapor-
phyrin and its magnesium complex (Fig. 5). The pro-
cess of thermooxidative decomposition of octaphenyl-
tetraazaporphyrin begins at 220 C and completes at
550 C, and it is accompanied by exothemic effects
(DTA, the maximum exothermic effect is observed at
505 C) and a full weight loss at the end of the process.
1
2
25
magnesium acetate is much higher than the corres- Compared with the ligand, the magnesium complex
ponding values for octaphenyltetraazaporphine; there- is less stable thermally (the respective temperatures
with, the activation energy and entropy are reduced
by almost half. Such a reduced activation energy
suggests stronger solvation of the reaction center of
the sulfamoyl derivative in the transition state.
for the ligand are 200, 600, and 530 C), which is
consistent with the regularities reported for porphyrin
ligands and complexes [15]. It should be noted that
octaphenyltetraazaporphyrin and Mg octaphenyltetra
azaporphyrin are less stable thermally than previously
studied porphyrins and porphyrin complexes, which
may be due to the peculiar molecular and crystal struc-
ture of the former and effects of the phenyl substituents.
The complex formation of octakis[p-(chlorome-
thyl)phenyl]tetraazaporphyrin in pyridine occurs by
a more complicated mechanism (Table 2). At the con-
5
4
centrations of Mg(OAc) from 6 10 to 5.9 10 M
2
the reaction order in magnesium acetate is zero, and
The thermogravimetric analysis of the crystal sol-
vate of Mg octaphenyltetraazaporphyrin with pyridine,
like of the crystal solvate of the ligand, was performed
in the range 15 150 C. The thermoanalytical curve
4
3
at the concentrations 8.9 10 and 1.18 10 M it is
.7. Probably, at higher salt concentrations the inter-
mediate amine complex formed by meso-nitrogen
0
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 7 2001

1064
KHELEVINA et al.
shows (Fig. 4) that the magnesium complex forms
with pyridine an extra complex of the composition
porphyrins were determined from the slopes of the
TG curves [21] and additionally checked by the elec-
tronic absoption spectra of samples taken below and
above that temperature. The physicochemical charac-
teristics of the molecular complexes of porphyrins
with pyridine were determined from the thermogra-
vimetric data, according to [22]. The reproducibility
of the thermoanalytical curves was controlled by five
runs with freshly prepared samples.
MgTAP(Ph) 2PyH which is stable in crystal solvate
8
up to 86 C ( H 53.2 0.3 kJ/mol). The presence in
the crystal solvate of the energetically stable complex
MgTAP(Ph) 2PyH gives us grounds to propose that
8
in pyridine, too, Mg(II) in the Mg complex takes up
in the course of complex formation two pyridine
molecules as extra ligands. Analogous data on the
composition of pyridine extra complexes have been
obtained for other magnesium(II) porphyrins [16].
ACKNOWLEDGMENTS
EXPERIMENTAL
The authors are grateful to V.P. Kulinich and S.I.
Vasil’ev for supplying the sample of octakis[p-(do-
decylsulfamoyl)phenyl]tetraazaporphyrin.
Octaphenyltetraazaporphyrin and octakis[p-
(
chloromethyl)phenyl]tetraazaporphyrin were obtained
by the procedures in [17] and [18], respectively.
Pyridine and diethylamine were purified and dried by
the procedures in [19]. Magnesium acetate of che-
mical grade was recrystallized from glacial acetic acid.
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nov i ftalotsianina (Coordination Compounds of
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Kinetic measurements were performed in a tempe-
rature-controlled cell of a Specord M-40 spectrophoto-
meter, where we placed solutions of octaarylporphy-
rine and magnesium acetate of specified concentra-
tions and at a specified temperature and measured in
certain intervals the optical densities of the solutions
at the absorption maxima of the resulting complexes
1
978.
2
. Stuzhin, R.A. and Khelevina, O.G., Coord. Chem.
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{
637 nm for Mg octaphenyltetraazaporphyrin, 642
4. Stuzhin, P.A., Khelevina, O.G., and Berezin, B.D.,
nm for Mg octakis[p-(dodecylsulfamoyl)phenyl]-
tetraazaporphyrine, and 646 nm for Mg octakis[p-
Zh. Fiz. Khim., 1987, vol. 61, no. 1, pp. 82 85.
5
6
7
. Khelevina, O.G. and Rumyantseva, S.V., Koord.
Khim., 1999, vol. 25, no. 4, pp. 261 264.
(
chloromethyl)phenyl]tetraazaporphyrin}. The current
and final concentrations of octaaryltetraazaporphyrines
were determined by Eq. (9):
. Khelevina, O.G. and Rumyantseva, S.V., Koord.
Khim., 1999, vol. 25, no. 5, pp. 330 333.
. Berezin, B.D, Khelevina, O.G., Gerasimova, N.D.,
and Stuzhin, P.A., Zh. Fiz. Khim., 1982, vol. 56,
no. 11, pp. 2768 2772.
c = c (A
A )/(A0
A ).
(9)
0
Here A , A , and A are the optical densities at the
0
beginning of the reaction, at time , and at the end of
8. Velazques, C.S., Broderick, W.E., Sabat, M., Bar-
ret, A.G.M., and Hoffman, B.M., J. Am. Chem. Soc.,
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the reaction; c and c are the initial and current con-
0
centrations of tetraazaporphyrin.
9
. Phthalocyanines: Properties and Applications,
Leznoff, C.C. and Lever, A.B.P., Eds., New York:
VCH, 1996, vol. 4, pp. 19 77.
Thermal analysis was performed on a MOM-1
0
00D derivatograph (Hungary). Before analysis the
compounds were dried to constant weight at 25
00 C. Crystal solvates were prepared by a procedure
similar to that described in [20] and involving slow
crystallization from concentrated solutions at 25 40 C.
To remove weakly bound solvent molecules, the crys-
tal solvate was dried in a vacuum to constant weight
1
10. Whalley, M.J., J. Chem. Soc., 1961, no. 3, pp. 866
869.
1
1
1
1. Khelevina, O.G., Chizhova, N.V., and Berezin, B.D.,
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2. Khelevina, O.G. and Petrov, O.A., Koord. Khim.,
(
25 50 C). The samples were 30 40 (tetraazapor-
1
997, vol. 23, no. 11, pp. 803 811.
3. Bureiko, S.F. and Oktyabr’skii, V.P., Kinet. Katal.,
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phyrines and complexes) or 10 25 mg (crystal sol-
vates). The heating rate in the analysis of crystal sol-
vates in nonisothermal conditions was 0.6 deg/min.
The heating rate in thermal decomposition studies was
1
14. Kompleksoobrazovanie v nevodnykh rastvorakh (Com-
5
deg/min. The decomposition temperatures T of
plex Formation in Nonaqueous Solutions), Kres-
d
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19. Organikum: organisch-chemisches Grundpraktikum,
Berlin: Wissenschaften, 1976, 15 ed. Translated under
the title Organikum: praktikum po organicheskoi
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1
5. Lebedeva, N.Sh., Antina, E.V., Berezin, M.B., Semei-
kin, A.S., and Bukushina, G.B., Zh. Fiz. Khim., 2000,
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0. Kirner, I.F., Reed, C.A., and Scheidt, W.R., J. Am.
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1
1
6. Miller, J.R. and Dorough, G.D., J. Am. Chem. Soc.,
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952, vol. 7, no. 16, pp. 3977 3981.
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8. Petrova, R.A., Khelevina, O.G., Berezin, B.D., and
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forov, M.Yu., and Krestov, G.A., Zh. Neorg. Khim.,
1990, vol. 35, no. 2, pp. 400 404.
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