METAL COMPLEXES OF A HEXAMERIC NETWORK TETRAPYRAZINOPORPYRAZINE: I.
983
For correct analyses, samples of the synthesized
polymers were dried in a vacuum under thermogravi-
metric control (until weight loss and the endothermic
effect at 100 150 C were no longer observed).
obtain 7.5 g (67%) of compound V as a yellow crys-
talline powder readily soluble in alcohols and acetone
and insoluble in water, mp 180 C {published data:
mp 181 183 C [8]}. Found, %: C 50.95; H 4.72; N
1
0.16. C H N O . Calculated, %: C 51.43; H 4.28;
12 12 2 8
The elemental analyses and equivalent molecular
weights of compounds IIa IIc are given in Table 2.
These data show that our developed procedure
allowed us to synthesize metal complexes of a hexa-
meric henwork tetrapyrazineporphyrazine with an
average polymerization degree of 6.
N 10.00.
Pyrazine-2,3,5,6-tetracarboxamide (VI). A sus-
pension of 10 g of ester V in 200 ml of anhydrous
methanol was saturated at room temperature within
one hour with dry ammonia and left to stand for one
day. The reaction mixture was separated by filtration,
the precipitate was triturated with water, squeezed,
and dried at 150 C to obtain 6 g (96%) of compound
VI as a yellow finely crystalline powder insoluble in
water and organic solvents, mp 390 C {published data:
mp 390 C [8]}. Found, %: C 38.78; H 3.10; N 33.79.
C H N O . Calculated, %: C 38.09; H 3.17; N 33.33.
EXPERIMENTAL
The electronic absorption spectra of 10 5 M solu-
tions of substances in corresponding solvents were
recorded on a Perkin-Elmer Lambda-20 spectrophoto-
meter in 10-mm quartz rectangular cells.
8
8
6
4
Mixture III of 2,3-diaminophenazine and 2-
amino-3-hydoxyphenazine. A solution of 406 g of
FeCl 6H O in 750 ml of distilled water was added
Metal complexes of hexameric network tetra-
pyrazineporphyrazine IIa IIc. A thoroughly ground
mixture of 7.56 g of amide VI, 20 g of carbamide, and
0.2 g of (NH ) MoO was slowly heated with stirring
3
2
with stirring to a solution of 54 g of ophenylenedi-
amine in 2 l of distilled water acidified with 84 ml of
4
2
4
to 170 C. When the reaction mixture became dark, a
thoroughly ground mixture of 0.5 g (NH ) MoO , 2.5
3
HCl ( 1.19 g cm ). The reaction mixture was held
4
2
4
for one day at 20 C and 1 atm, then the resulting
precipitate was filtered off, washed with 0.3 N HCl to
g of carbamide, and 18 mmol of an anhydrous metal
salt (2.42 g of CuCl , 2.59 g of FeC O , or 2.34 g
2
2
4
remove FeCl , and dried up at 60 C. A reddish brown
CoCl ) was added , and the mixture was heated at
3
2
powder of the mixture of practically equal amounts of
200 C for 3 h with stirring. Then a thoroughly ground
mixture of 0.05 g of (NH ) MoO , 5 g of carbamide,
2,3-diamino-phenazine and 2-amino-3-hydoxyphena-
4
2
4
zine was obtained with a near-quantitative yield and
used in the further synthesis without separation into
individual components.
and 9 mmol of an anhydrous metal salt (1.41 g of
CuCl , 1.29 g FeC O , or 1.17 g CoCl ) was added,
and the melt was stirred for 1.5 ½ at 200 C until it
solidified, after which 10 g of carbamide was added.
The mixture liquefied and was stirred for 1.5 h at
2
2
4
2
Pyrazine-2,3,5,6-tetracarboxylic acid (IV). To a
suspension of 19.5 g of mixture III in a solution of
2
00 C and then cooled. The greenish black melt was
1
2.5 g of KOH in 1 l of water, 158 g of KMnO was
4
treated with hot water up to colorless extracts and
washed sequentially with 5% HCl, hot water, and
acetone to colorless filtrates. The dry powder was
dissolved in a 20-fold amount of concentrated sulfuric
acid, filtered on a Schott filter no. 3, and reprecipi-
tated onto ice. The precipitate was filtered off, washed
sequentially with hot water up to a neutral filtrate and
with acetone, and dried in a vacuum oven at 200 C
added in small portions with stirring at 70 80 C. The
mixture was stirred for 4 h more and separated by
filtration. The precipitate of MnO was washed with
2
hot water up to a negative reaction of washins for
FeSO . The combined filtrate was evaporated until
4
crystallization began and acidified with HCl (
3
1
.19 g cm ) to pH 2 3. After cooling, a pale yellow
finely crystalline powder of the target reaction product
formed and was isolated by filtration. It is soluble in
water, alcohol, and acetone; yield 21 g (91%), mp
(
2.7 kPa) to obtain compounds IIa IIc as finely crys-
talline, nonmelting, hygroscopic powders of black
color with a metal shine, insoluble in organic solvent.
Yield: IIa 3.9 g (58%), IIb 3 g (45%), and IIc 2.8 g
1
%
%
98 C {published data: mp 198 199 C [8]}. Found,
: C 38.87; H 1.63; N 10.76. C H N O . Calculated,
8
4
2
8
(42%).
: C 37.50; H 1.56; N 10.94.
Tetramethyl pyrazine-2,3,5,6-tetramethylcar-
The equivalent molecular weights of the polymers
were determined by potentiometric back titration with
0.05 N HCl solutions of samples prepared by keeping
boxylate (V). A solution of 10 g of acid IV in 100 ml
of methanol was saturated by dry hydrogen chloride
at cooling. The reaction mixture was left to stand for
one day and diluted with water. A precipitate formed
and was filtered off, washed, and dried in air to
0.1 g of (PzcM) in 20 ml of 0.05 N NaOH for 12 h.
n
In parallel, a control experiment was carried out. An
accurate weighed portion of a substance was held in
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 6 2005
Korzhenevskii
