The review is devoted to the key achievements of the Laboratory of Chemistry of Nitro Compounds at the Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences since its founding by ...Academician of the Russian Academy of Sciences V. A. Tartakovsky in 1971. The main attention is paid to the structural factors affecting the stability of polynitrogen-oxygen systems (PNO systems), design rules for new stabilized PNO systems, and new synthetic methods towards such systems. The synthesis of dinitramide salts, 1,2,3,4-tetrazine 1,3-dioxides, nitro-
NNO
-azoxy compounds, and other new classes of PNO systems is considered in detail. The advances in synthesis of new types of
N
-nitroamines are also considered.
The crystal structure of a novel high-energy density material 3-(3,4-dinitro-1H-pyrazol-1-yl)-NNO-azoxy-4-nitro-1,2,5-oxadiazole C5HN9O8 was determined and refined using laboratory powder diffraction ...data. The diffraction data and database analysis were insufficient to distinguish two candidate structures from the solution step. Density functional theory with periodic boundary conditions optimizations were used to choose the correct one. 3-(3,4-Dinitro1H-pyrazol-1-yl)-NNO-azoxy-4-nitro-1,2,5-oxadiazole crystallizes in space group Pbca with a = 8.3104(2) Å, b = 14.2198(5) Å, c = 19.4264(7) Å, V = 2295.66(14) Å3. The molecular conformation contains a weak intramolecular hydrogen bond C–H⋯O–N, and the structure is dominated by weak O⋯π and O⋯O contacts.
The crystal structure of a novel high-energy density material 3,3′-(E)diazene-1,2-diylbis{4-(3,4-dinitro-1H-pyrazol-1-yl)-NNO-azoxy-1,2,5-oxadiazole} (C10H2N18O12) was determined and refined using ...laboratory powder diffraction data. The title compound crystallizes in space group P21/c with a = 9.5089(3) Å, b = 11.6331(4) Å, c = 10.6270(3) Å, β = 116.2370(12), V = 1054.43(6) Å3. The asymmetric unit contains half of the molecule. The molecular conformation contains a weak intramolecular hydrogen bond C–H⋯O–N, both nitro groups are disordered, and the structure is dominated by weak O⋯π and O⋯O contacts.
The reaction of 3-amino-4-(3-nitro-1
H
-1,2,4-triazol-1-yl)-
NNO
-azoxyfurazan (
4a
) with 2,2,2-trifluoro-
N
-(4-nitrosofurazan-3-yl)acetamide (
6
) in the presence of dibromoisocyanuric acid (DBI) ...followed by removal of the protective trifluoroacetyl group gives 3-amino-4-({4-(3-nitro-1
H
-1,2,4-triazol-1-yl)-
NNO
-azoxyfurazan-3-yl}-
NNO
-azoxy)furazan (
5a
). This compound contains a new explosophore (3-nitro-1
H
-1,2,4-triazol-1-yl)-
NNO
-azoxy moiety. The oxidation of the amino group in aminofurazan
5a
with an excess N
2
O
5
of resulted in the corresponding nitro derivative
5b
. Aminofurazan
5a
reacted with DBI to give the corresponding azo compound
5c.
Compounds
5a,c
may be of interest as energetic substances due to the combination of good thermal stability and high calculated enthalpy of formation (827 and 953 kcal kg
−1
, respectively).
Methylation and amination reactions of 4
Н
-1,2,3triazolo4,5-
c
1,2,5oxadiazole salts (K
+
, Ag
+
, Et
3
NH
+
, DBUH
+
) have been studied for the first time. It has been shown that the reaction of ...these salts with MeI results in two methylation products: K and Et
3
N salts produce 4- and 5-isomers in equal amounts, while Ag and DBU salts form mainly 4-isomer. It has been found that the main amination product of K and DBU salts of 4
Н
-1,2,3triazolo4,5-
c
1,2,5oxadiazole with
O
-(
p
-tolylsulfonyl)hydroxylamine is 4-azido-3-amino-1,2,5-oxadiazole. A mechanism of its formation via rearrangement of 5-amino-1,2,3triazolo4,5-
c
1,2,5oxadiazole has been proposed.
Polytene chromosomes in
Drosophila
serve as a classical model for cytogenetic studies. However, heterochromatic regions of chromosomes are typically under-replicated, hindering their analysis. ...Mutations in the
Rif1
gene lead to additional replication of heterochromatic sequences, including satellite DNA, in salivary gland cells. Here, we investigated the impact of the
Rif1
mutation on heterochromatin in polytene chromosomes formed in ovarian germ cells due to the
otu
gene mutation. By the analysis of
otu
11
; Rif1
1
double mutants, we found that, in the presence of the
Rif1
mutation, ovarian cells undergo additional polytenization of pericentromeric regions. This includes the formation of large chromatin blocks composed of satellite DNA. Thus, the effects of the
Rif1
mutation are similar in salivary gland and germ cells. The
otu
11
; Rif1
1
system opens new possibilities for studying factors associated with heterochromatin during oogenesis.
Energetic compounds containing a new explosophoric fragment, (3,4-dinitro-1
H
-pyrazol-1-yl)-
NNO
-azoxy group, and furazan rings linked by azo and azoxy bridges were synthesized. Furazans obtained ...combine a high calculated enthalpy of formation and acceptable thermal stability and are of interest as potential components of energy-rich materials.
At heating of 2-(2-azido-3,5-dinitrophenyl)-2
H
-1,2,3triazolo4,5-
e
1,2,3,4tetrazine 4,6-dioxide in toluene at 110 °C, the azido group interacts mainly with the neighboring nitro group and to a ...lesser extent with the neighboring 1,2,3-triazole ring, resulting in 2-(6-nitrobenzofuroxan-4-yl)-2
H
-1,2,3triazolo4,5
-e
1,2,3,4tetrazine 4,6-dioxide
(2)
in 68% yield, as well as 8,10-dinitro-5,11-dehydro-5
H
,11
H
-1,2,3,4tetrazino5′,6′:4,5-1,2,3triazolo2,1-
a
1,2,3benzotriazole 1,3-dioxide and 8,10-dinitro-5,11-dehydro-5
H
,11
H
-1,2,3,4tetrazino5′,6′:4,51,2,3triazolo2,1-
a
1,2,3benzotriazole 2,4-dioxide in 5% yields respectively. Furoxan
2
may be of interest as an energetic compound due to the combination of good thermal stability, positive estimated enthalpy of formation (Δ
H
°
f
= 1005 kJ mol
−1
) and optimal density.
A reaction of 5-amino-6-(
tert
-butyl-
NNO
-azoxy)-1,2,3,4-tetrazine 1,3-dioxide with nitronium tetrafluoroborate affords 5-amino-6-(nitro-
NNO
-azoxy)-1,2,3,4-tetrazine 1,3-dioxide, which can be of ...interest as an energetic compound. A plausible mechanism of its formation involves substitutive nitration of the
tert
-butyl group.
The standard enthalpies of formation of nitro-
NNO
-azoxy compounds including nitro-
NNO
-azoxybenzene (
2
), 3-nitro-4-{4-(nitro-
NNO
-azoxy)furazan-3-yl-
NNO
-azoxy}-furazan (
4
), and ...bis-4,4′-(nitro-
NNO
-azoxy)-3,3′-azofurazan (
6
), as well as those of nitro compounds including 3-nitro-4-(4-nitrofurazan-3-yl)-
NNO
-azoxyfurazan (
3
) and 4,4′-dinitro-3,3′-azofurazan (
5
) were determined by combustion calorimetry. It was shown that replacement of nitro group by nitro-
NNO
-azoxy group in the benzene and furazan rings causes the enthalpies of formation of the nitro-
NNO
-azoxy compounds to increase by 49–57 kcal mol
−1
(on the average, by 52 kcal mol
−1
per nitro-
NNO
-azoxy group introduced). According to the detonation velocity and detonation pressure calculations for compounds
3–6
, the energetic characteristics of nitro-
NNO
-azoxyfurazans
4
and
6
approach those of hexanitrohexaazaisowurtzitane (CL-20), being much better than those of nitrofurazans
3
and
5
.
