Control of Biohazards: A High Performance Energetic Polycyclized Iodine-Containing Biocide

Article abstract of DOI:10.1021/acs.inorgchem.8b01600

Biohazards and chemical hazards as well as radioactive hazards have always been a threat to human health. The search for solutions to these problems is an ongoing worldwide effort. In order to control biohazards by chemical methods, a synthetically useful fused tricyclic iodine-rich compound, 2,6-diiodo-3,5-dinitro-4,9-dihydrodipyrazolo [1,5-a:5′,1′-d][1,3,5]triazine (5), with good detonation performance was synthesized, characterized, and its properties determined. This compound which acts as an agent defeat weapon has been shown to destroy certain microorganisms effectively by releasing iodine after undergoing decomposition or combustion. The small iodine residues remaining will not be deleterious to human life after 1 month.

Full text of DOI:10.1021/acs.inorgchem.8b01600

Article
pubs.acs.org/IC
Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
Control of Biohazards: A High Performance Energetic Polycyclized
Iodine-Containing Biocide
Gang Zhao,† Chunlin He,† Wenfeng Zhou,‡ Joseph P. Hooper,§ Gregory H. Imler,∥
Damon A. Parrish,∥ and Jean’ne M. Shreeve*,†
†Department of Chemistry, University of Idaho, Moscow, Idaho 83844-2343, United States
‡Department of Applied Chemistry, China Agricultural University, Beijing, 100193 China
§Department of Physics, Naval Postgraduate School, Monterey, California 93943, United States
∥Naval Research Laboratory, Code 6030, Washington, District of Columbia 20375-5001, United States
S
* Supporting Information
ABSTRACT: Biohazards and chemical hazards as well as
radioactive hazards have always been a threat to human health.
The search for solutions to these problems is an ongoing
worldwide effort. In order to control biohazards by chemical
methods, a synthetically useful fused tricyclic iodine-rich
compound, 2,6-diiodo-3,5-dinitro-4,9-dihydrodipyrazolo [1,5-
a:5′,1′-d][1,3,5]triazine (5), with good detonation perform-
ance was synthesized, characterized, and its properties
determined. This compound which acts as an agent defeat
weapon has been shown to destroy certain microorganisms
effectively by releasing iodine after undergoing decomposition
or combustion. The small iodine residues remaining will not
be deleterious to human life after 1 month.
This prevents the micro-organisms from being able to make
important proteins that are necessary for survival, so they die.
The destruction of certain bacteria, amoebic cysts, and viruses
(a 99.999% kill in 10 min at 25 °C) may require I2 residuals of
0.2, 3.5, and 14.6 ppm, respectively.15 However, due to the
ready sublimation of iodine, it is not practical to use the
element itself as an ingredient in an ADW. Iodine-rich
compounds in which the iodine exists as C−I, iodide or
iodate exhibit relatively better thermal stability and therefore,
can be used as potential ingredients for ADWs.16
Many polyiodide compounds have been synthesized and
developed over two generations of ADWs. Among these
compounds, 3,4,5-triiodo-1H-pyrazole (TIPy) (a),16,18 tetraio-
dofuran (TIF) (b),16 and 4,5-diiodo-[1H]-1,2,3-triazole (c)19
are typical compounds of first-generation ADWs (Figure 1).
They exhibit good thermal stability but low detonation
performance.
1. INTRODUCTION
Biohazards are biological substances such as microorganisms,
viruses, or toxins that threaten living organisms,1 including
humans as exemplified by smallpox,2 plague,3 cholera,4 and
more recently, SARS,5 bird flu,6 and Ebola viruses.7 Although
the use of biological weapons is prohibited under international
humanitarian law8 as well as by a variety of international
treaties and their use in armed conflict is deemed a war crime,
some countries and organizations continue to synthesize and
utilize biological agents. Because of the attractive properties of
Bacillus anthracis,9 including physical shape, thermal stability,
and resistance to many disinfectants (including 95%
ethanol),10 its endospores are extraordinarily well-suited for
use (in powdered and aerosol form) as a biological weapon as
demonstrated by some countries in the past.11 Large quantities
of chemical and biological weapons are stored by various
countries and illegitimate groups around the world.11
Since a biological weapon may be a bacterium, virus,
protozoan, parasite, or fungus that can be used as a weapon in
bioterrorism or biological warfare,12 it is necessary to develop
agent defeat weapons (ADWs) in order to destroy or
neutralize the active agents by releasing large amounts of
strong biocides after detonation.13−17 Based on molecular
biology, the mechanism of iodine as a bactericide may arise
from oxidation and iodination reactions of cellular proteins and
nucleic acids.15 Iodine damages the walls of the cells that make
up the micro-organisms and causes the contents to leak out.15
However, one of the problems with application of first-
generation ADWs is the difficulty in obtaining complete
combustion because of their low detonation performance ((a)
P = 5.32 GPa: Dv = 2859 m/s; (b) P = 4.29 GPa: Dv = 2417
m/s), thus reducing the bactericidal effect.20 Residual
compounds may also pollute the environment, so an oxidizer
Received: June 8, 2018
© XXXX American Chemical Society
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2. RESULTS AND DISCUSSION
In an attempt to realize an ideal balance between high
performance and molecular stability, 2,6-diiodo-3,5-dinitro-4,9-
dihydrodipyrazolo [1,5-a:5′,1′-d][1,3,5]triazine (5) was syn-
thesized and characterized. Incorporating the nonaro-
matic1,3,5-triazinane with pyrazoles results in the fused
tricyclic (5) which has a nearly planar structure with enhanced
thermal behavior as well as better detonation performance.
The synthesis of fused tricyclic compound 5 takes advantage
of bis(3,4,5-triiodo-1H-pyrazol-1-yl)methane (2) as the
starting material, which was obtained readily from 3,4,5-
triiodopyrazolium with diiodomethane (Scheme 1). Com-
pound 1 was synthesized analogously. Nitration of 2 gave
bis(3,5-diiodo-4-nitro-1H-pyrazol-1-yl)methane (3) which was
treated with ammonia−DMSO solution to form pure
ammonium salt 4 with a tricyclic framework. Neutralization
of 4 using 10% aqueous hydrochloric acid gives 5. All
compounds were confirmed by NMR, IR, DSC and elemental
analysis. The carbon−nitrogen ratio is a very important
indicator of detonation performance for ADWs. The smaller
the carbon−nitrogen ratio (mass), the more energetic and
effective the materials are.20 Compounds 1 and 2 have the
same carbon−nitrogen ratio of C/N = 1.5, while 3 is lower at
C/N = 1.0. Compounds 4 and 5 have carbon−nitrogen ratios
of C/N = 0.75 and 0.85, respectively. Therefore, they are
Figure 1. (a−c) First-generation ADWs. (d−f) Second-generation
ADWs. Bottom panel: target molecule.
1
expected to be the most energetic. In the H NMR spectrum,
or combustion adjuvant must be used with these polyiodide
compounds in order for complete combustion to occur.
Further work was focused on improving the detonation
performance of iodine-rich compounds by introducing
energetic groups which resulted in the second-generation of
agent defeat weapons. The introduction of nitro, nitramine, or
tetrazole groups was a successful strategy such as seen in (e)
and (f) [(e) P = 15.20 GPa: Dv = 5555 m/s; (f) P = 9.50 GPa:
Dv = 3767 m/s].20,21 Additionally, the combination of an
the methylene bridge resonates between 6.06 and 6.65 (s)
ppm. In the 13C NMR spectra, the peak assigned to the
methylene bridge carbon is at 62−67 ppm and the chemical
shift for C−I is at 86−110 ppm.
Crystallographic data and data collection parameters, bond
lengths, and bond angles are given in the Supporting
Information. Compounds 3 and 4 crystallize in the triclinic
̅
space group P1, while 5 crystallizes in the tetragonal space
group P43212 (Figures 2−4).
−
−
−
iodine-rich cation with IO3 , IO4 , or I3O8 as anion in a
prospective biocide to ensure a high iodine content and
improve the oxygen balance as well was attempted. For
example, (d) has a good detonation performance (P = 13.80:
GPa: Dv = 4558 m/s) and oxygen balance.17 However, the
introduction of energetic groups reduces thermodynamic
stability. The decomposition temperatures of (d) and (e) are
149 and 111 °C, respectively. Compound (f) has a high
decomposition temperature (270 °C) but low detonation
performance.
Compound 3 is in a gauche conformation with the angles
between the pyrazole rings along the C−C axis at 81.5(6)°.
The dihedral angle between the mean planes through the
tetrazole rings is 100.7(2)°. The nitro groups in 3 bonded to
the pyrazole ring are not coplanar with an angle (26.6(3)°)
due to steric hindrance. For 4 and 5, all the atoms of the fused
tricyclic framework are nearly coplanar.
Impact sensitivity (IS) measurements were made by using
standard BAM techniques.22 All the iodine-rich compounds
Scheme 1. Preparation of Compounds 1−5
B
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obtained by combining the MP2/6-311++G** energy differ-
ence for the reactions, the scaled zero-point energies (ZPE),
values of thermal correction (HT), and other thermal factors.
Compound 5 has the highest heat of formation (1192.69 kJ
mol−1). The heat of formation of 3 is larger than those of 1 and
2 due to introduction of nitro groups (976.87 kJ mol−1). On
the basis of the calculated values for heats of formation and
experimental densities, the detonation velocities (Dv) and
pressures (P) were obtained using Cheetah 7.0. Compared
with 3,4,5-triiodopyrazole (TIPy) (Table 1), 3 and 5 have
higher detonation pressures ranging from 17.31 to 21.48 GPa
and higher detonation velocities from 4627 to 5834 m/s. With
a detonation performance of 21.48 GPa: 5834 m/s, 5
approaches TNT (19.50 GPa: 6881 m/s). The decomposition
products of the iodine-rich compounds are important in
evaluating the ability to destroy or neutralize an active agent
(Table 2). Given are the major detonation products of 1−3
Figure 2. (a) Thermal ellipsoid plot (50%) and labeling scheme for 3.
(b) Ball-and-stick packing diagram of 3 viewed down the b axis.
Dashed lines indicate strong hydrogen bonds.
Table 2. Detonation Products: Cheetah 7.0 [wt% kg−1]
Figure 3. (a) Thermal ellipsoid plot (50%) and labeling scheme for 4.
(b) Ball-and-stick packing diagram of 4 viewed down the b axis.
Dashed lines indicate strong hydrogen bonds.
comp
I2 (g)
N2 (g)
HI (g)
CH4 (g)
C (s)
CO2 (g)
1
2
3
5
84.21
84.21
67.74
49.67
52.10
6.20
6.20
11.33
19.49
6.22
0.06
0.06
0.92
0.80
22.87
0.88
0.88
1.05
2.36
8.64
8.64
7.31
11.86
17.48
8.00
10.18
TIPy
and 5 at STP (T = 298 K, P = 1 atm). On the basis of the
detonation products, they are potential candidates to be
effective bio agent-defeat materials because of the high
percentage of I2: 1 and 2 have markedly higher iodine
concentrations at 84.21%, while 3 and 5 have iodine
concentrations at 67.74 and 49.67%, respectively.
Figure 4. (a) Thermal ellipsoid plot (50%) and labeling scheme for 5.
(b) Ball-and-stick packing diagram of 5 viewed down the b axis.
Dashed lines indicate strong hydrogen bonding.
Thermal stability is a very important property for any
energetic molecule. The thermal behavior of compounds 1−3
was determined with a differential scanning calorimeter (DSC)
scans at a heating rate of 5 °C/min. Compounds 1 and 2
decompose at 264 and 351 °C (onset temperatures),
respectively. After introducing the nitro groups, 3 has a good
thermal stability, decomposing at 320 °C (onset temperature).
Because of the fused tricyclic framework, 5 has an excellent
thermal stability decomposing at 323 °C (Figure 5). Densities
were measured using a gas pycnometer at 25 °C and found
between 2.56−3.66 g cm−3. The replacement of an iodine
atom with a nitro group leads to a decrease in density (Table
1). Compound 5 has a density of 2.56 g cm−3. If an ADW does
not decompose completely upon heating or combustion, then
there will be a reduced bactericidal effect. The DSC curve of 5
shows a sharp peak at 323 °C suggesting that 5 decomposed or
have IS values ranging between 9 and 40 J. Compounds 1 and
2 are insensitive at 40 J. After introducing nitro groups, the
impact sensitivity of 3 is found to be 11 J. Although 5 has a
more stable fused tricyclic frame structure and a higher
nitrogen content, it has an impact sensitivity (8 J) greater than
3. This probably arises because of the higher nitrogen content
and additional molecular strain and crystal packing of 5 (Table
1).
Heats of formation were calculated using the Gaussian 03
(Revision D.01) suite of programs.23 For iodine-rich cations,
the (15s, 11p, 6d) basis of Stromberg et al.24 was augmented
with another p shell and the five valence sp exponents
optimized, resulting in a [5211111111, 411111111, 3111]
contraction scheme in conjunction with 6-31+G** for first-
and second-row elements. The heats of formation were
Table 1. Physicochemical Properties of Compounds 1−5
a
b
c
d
e
f
g
comp
Td (°C)
d (g/cm3)
ΔHf° (kJ/mol)
D (m/s)
P (GPa)
iodine (%)
OB (%)
IS (J)
1
2
3
5
264
351
320
323
272
295
3.60
3.66
2.94
2.56
3.38
1.65
536.59
520.71
976.87
1192.69
461.1
2670
2766
4625
5834
2859
6881
4.34
4.76
17.31
21.48
5.32
84.27
84.27
68.44
50.46
85.4
0
−14
−14
−8
−14
−12
−25
>40
>40
11
9
>40
15
TIPy16
TNT17
−31.7
19.5
a
b
c
d
Decomposition temperature (onset). Measured density at 25 °C. Calculated heat of formation. Detonation velocity, CHEETAH 7.
e
f
g
Detonation pressure, CHEETAH 7. Oxygen balance CaHbOcNdIe: OB = 1600(c − b/2 − a)/MW. Impact sensitivity measured via BAM method.
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bath, and 5 mL of deionized water was added. This mixture
was poured onto a culture medium (lysogeny broth (LB), a
nutritionally rich medium, primarily used for the growth of
bacteria, and agar) that was coated with bacteria (mixed
bacteria, E. coli or S. aureus, labeled as a−d, separately. The
blank test (BL) was run by pouring 5 mL of deionized water
onto the culture medium that was coated with bacteria.
Because ADWs deal with microorganisms in air, water, and
topsoil in the infected zone, carrying out the biotest at 25 °C is
reasonable. The antibacterial activity experiment was incubated
at 25 °C for 13 days and then evaluated. In Figures 6−8, BL
and a−d correspond to the blank test and the decomposition
products of 5, 10, 25, and 50 mg of 5, respectively. Carbon
produced during decomposition (black spot) is seen in a−d.
In Figure 6, BL1 shows the growth of S. aureus from 24 h.
From a1−a5, b1−b5, c1−5, d1−d5 in Figure 6, even treated
with decomposition products of 5 mg of (a1−a5), no colony of
S. aureus can be seen for more than 13 days. Therefore, it can
be seen that the decomposition products of 5 have very good
antibacterial activity against Gram-positive bacteria.
In Figure 7, from BL2, E. coli covers the entire medium, and
the medium becomes cloudy because of its growth after 96 h.
As in Figure 6, treating E. coli with decomposition products of
different amounts of 5, a1−a5, b1−b5, c1−c5, and d1−d5 in
Figure 7 show a very good bactericidal effect, and no colony of
E. coli can be seen for more than 13 days. This indicates the
decomposition products of 5 have very good antibacterial
activity against Gram-negative bacteria.
Figure 5. DSC curve of 5.
combusted completely. Therefore, 5 may have the potential to
be an excellent ADW.
In order to determine the qualitative biocidal capability of 5,
a modified method to test this property of these materials
based on a reported procedure was used.20 We chose skin
surface and airborne bacteria (may contain B. subtilis and
Staphylococcus aureus, Salmonella, etc.) to simulate a real
environment since there are many different kinds of bacteria in
the actual environment and since iodine is a broad-spectrum
bactericide. In order to better understand the bactericidal effect
of iodine, Escherichia coli representing Gram-negative bacteria
and S. aureus representing Gram-positive bacteria were chosen
since these bacteria are widely distributed on the earth and
they are readily available. Methicillin-resistant S. aureus is often
referred to as a “superbug”,25 and B. anthracis also belongs to
the Gram-positive bacteria group.
In Figure 8, coating mixed bacteria after 72 h, BL3 shows
that the growth of mixed bacteria starts after 96 h. For a−d,
after 312 h (13 days), a1−a5, b1−b5, c1−c5, and d1−d5 show
that the exposed bacteria do not survive in the culture medium.
It can be seen that the decomposition products of 5 kill almost
all microorganisms in air and surface soil in the infected zone.
From the biotest, after decomposition of 5, all microorganisms
appear to have been killed effectively and the environment was
In a 25 mL round-bottomed flask, 5, 10, 25, or 50 mg of
iodine-rich 5 was decomposed by heating at about 400 °C for
∼3 min. The flask was cooled to room temperature in a water
Figure 6. Comparison [312 h (13 days) after treatment] of the treatment of S. aureus with decomposition products of different amounts of 5 (BL:
blank test, a: 5 mg, b: 10 mg, c: 25 mg, d: 50 mg).
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Figure 7. Comparison [312 h (13 days) after treatment] of the treatment of E. coli with decomposition products of different amounts of 5 (BL:
blank test, a: 5 mg, b: 10 mg, c: 25 mg, d: 50 mg.
Figure 8. Comparison [312 h (13 days) after treatment] of the treatment of skin surface bacteria and airborne bacteria (may contain B. subtilis, S.
aureus, Salmonella, etc.) with decomposition products of different amounts of 5 (BL: blank test, a: 5 mg, b: 10 mg, c: 25 mg, d 50 mg).
kept clean for more than 13 days. As an ADW, 5 may control
areas of outbreak of any epidemic and effectively reduce the
risk of cross infection for affected areas of people and animals
as well as medical staff. From the biotest, it is seen that the
decomposition products of 5 mg of 5 might control an area of
one plate (about 63 cm2). Assuming an outbreak or attack by
biological weapons in a big city (100 km2), about 79.4 tons of
5 would be required as an ADW to annihilate most of the
microorganisms in air, water and topsoil in the infected zone.
In an infected zone treated with ADWs, the residual amount
of biocide would be a very important index for determining
whether compounds as ADWs are good or bad. If the
compounds are to be useful as Agent Defeat Weapons, the
quantity of released biocide after decomposition must be a
small amount with low toxicity, decomposition or biological
metabolism last for a short time, and not cause long-term
environmental pollution. Studies concerning residual biocides
released after decomposition or combustion of ADWs have
rarely been reported. Iodine-rich compounds are excellent
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Figure 9. Residual iodine content of culture-media treated with decomposition products of different amounts of 5 (left) and percentage of
retention of I2 in the media after one month (right).
scanning calorimeter (TA Instruments Co., model Q2000) at a
heating rate of 5 °C/min. IR spectra were recorded using KBr pellets
for solids on a BIORAD model 3000 FTS spectrometer. Densities
were determined at 25 °C by employing a Micromeritics AccuPyc
1340 gas pycnometer. Elemental analyses were carried out using an
Exeter CE-440 elemental analyzer. Impact sensitivity measurements
were made using a standard BAM Fallhammer. The residual iodine
amount was characterized by a reported UV spectrophotometric
method26 for content determination of iodine using a VWR
spectrophotometer UV-3100PC UV−vis. Potassium iodate (5.0 ×
10−5 mol/L), potassium iodide (2.5 × 10−3 mol/L), starch (0.5%),
sulfuric acid (1.0 mol/L), and distilled water were used. A wavelength
of 575 nm was chosen as the maximum absorption. The cell length
was 1 cm.
Caution! Although no explosions or hazards were observed during the
preparation and handling of these compounds, all the compounds
investigated are potentially explosive materials. Mechanical actions
involving scratching or scraping must be avoided. In addition, all of the
compounds must be synthesized only on a small scale. Manipulations must
be carried out in a hood behind a safety shield. Eye protection and leather
gloves must be worn at all times.
ADWs due to the iodine released upon decomposition or
combustion. Iodine is volatile and undergoes redox reactions
but does not cause substantial environmental pollution. In our
work, the amount of residual iodine was characterized by using
a reported UV spectrophotometric method (Supporting
Information).26 The iodine remaining on the media treated
with decomposition products of 5 after one month had
decreased to 0.008 mg (a: 5 mg), 0.017 mg (a: 10 mg), 0.115
mg (a: 25 mg), and 0.200 mg (a: 50 mg) (Figure 9). From
Table 2, the amount of I2 released after decomposition or
combustion of 5 is 49.67% which says 2.5 mg of I2 is obtained
when 5 mg of 5 is decomposed and so on. Therefore, the
percentages of retention of I2 on the media after one month are
0.32% (a), 0.34% (b), 0.92% (c), and 0.81% (d), respectively
which indicates that the quantity of residual iodine is so low
after one month in the affected areas that there will be no
deleterious effects on humans.
3. CONCLUSION
4.2. Bis(2,4,5-triiodo-1H-imidazol-1-yl)methane (1). To a
solution of the sodium salt of 3,4,5-triiodopyrazole (936 mg, 2
mmol) in acetonitrile (20 mL) was added diiodomethane (268 mg, 1
mmol), and the reaction was maintained at 80 °C for 4 h. After
cooling, the mixture was poured into cold water (40 mL), the off-
white precipitate obtained was filtered, washed with water (3 mL),
and dried in the air to give 812 mg of an off-white solid. Yield: 90%;
Compound 5 (2,6-diiodo-3,5-dinitro-4,9-dihydrodipyrazolo-
[1,5-a:5′,1′-d][1,3,5]triazine) was synthesized and character-
ized. The structures of three iodo compounds, 3−5, were
determined by single crystal X-ray diffraction. Compound 5
has a high density and iodine content and good detonation
properties (P = 21.48 GPa: Dv = 5834 m/s) approaching TNT
(P = 19.50 GPa: Dv = 6881 m/s), all of which suggest it as a
candidate as an ADW. With a sharp peak at 323 °C in the DSC
scan, 5 is likely combusted or decomposed at that temperature.
Because of the polycyclic dipyrazolo-1,3,5-triazinane backbone,
there are several advantages in density, planarity, molecular
stability, and energetic performance. From the biotest, after
decomposition of 5, all microorganisms in air, water, and
topsoil would have apparently been killed effectively, and the
environment remained uncontaminated for more than 13 days.
After 1 month, the residual iodine on the medium treated with
decomposition products of 5 has decreased to very low levels
indicating that there would likely be no deleterious effects on
living things from the iodine and pathogenic microorganisms.
T
d(onset) = 264 °C; 1H NMR (300 MHz, DMSO-d6, δ): 6.16 (s, 2H);
13C NMR (75 MHz, DMSO-d6, δ): 100.97, 97.87, 99.68, 86.79, 65.30
ppm; IR (KBr): ν = 1452 (m), 1380 (s), 1360 (m), 1320 (s), 1273
(m), 1208 (s), 1175 (m), 1085 (m), 996 (m), 938 (m), 789 (m), 761
(m), 651 (m), 615 (w), 481 (w), 425 cm−1 (m); Anal. Calcd for
C7H2I6N4 (903.45): C 9.31, H 0.22, N 6.20. Found: C 9.40, H 0.27,
N 6.21.
4.3. Bis(3,4,5-triiodo-1H-pyrazol-1-yl)methane (2). To a
solution of the sodium salt of 3,4,5-triiodopyrazole (936 mg, 2
mmol) in acetonitrile (20 mL) was added diiodomethane (268 mg, 1
mmol), and the reaction was maintained at 80 °C for 4 h. After
cooling, the mixture was poured into cold water (40 mL), and the
white precipitate was filtered, washed with water (3 mL), and dried in
the air to give 857 mg white solid. Yield: 95%; Td(onset) = 351 °C; 1H
NMR (300 MHz, DMSO-d6, δ): 6.49 (s, 2H); 13C NMR (75 MHz,
DMSO-d6, δ): 110.89, 100.14, 89.20, 67.65 ppm; IR (KBr): ν = 1534
(w), 1435 (s), 1408 (m), 1380 (m), 1366 (m), 1297 (s), 1230 (m),
1147 (w), 1039 (w), 1011 (s), 978 (m), 946 (w), 765 (m), 647 (w),
506 (w), 477 (w), 416 cm−1 (w); Anal. Calcd for C7H2I6N4 (903.45):
C 9.31, H 0.22, N 6.20. Found: C 9.39, H 0.26, N 6.24.
4. EXPERIMENTAL SECTION
4.1. General Methods. Reagents were purchased from Aldrich
1
and Acros Organics and were used as received. H, and 13C spectra
were recorded on a 300 MHz (Bruker AVANCE 300) nuclear
magnetic resonance spectrometer operating at 300.13 and 75.48
MHz, respectively. DMSO-d6 was used as solvent and locking solvent.
Chemical shifts in the 13C spectra are reported relative to Me4Si. The
melting and decomposition points were obtained with a differential
4.4. Bis(3,5-diiodo-4-nitro-1H-pyrazol-1-yl)methane (3).
Compound 2 (903 mg, 2 mmol) was added to 100% nitric acid (4
mL), and the reaction mixture was stirred at room temperature for 12
h and then poured into cold water (60 mL). The yellowish brown
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precipitate was filtered, washed with water (30 mL), and dried in air
ACKNOWLEDGMENTS
■
1
to obtain 518 mg. Yield: 70%; Td(onset) = 320 °C; H NMR (300
MHz, DMSO-d6, δ): 6.65 (s, 2H); 13C NMR (75 MHz, DMSO-d6,
δ): 140.28, 99.32, 95.93, 67.28 ppm; IR (KBr): ν = 3433 (w), 3035
(w), 2814 (w), 1757 (w), 1600 (w), 1517 (s), 1441 (m), 1391 (m),
1376 (s), 1348 (s), 1315 (m), 1129 (w), 1070 (m), 1040 (w), 999
(w), 954 (w), 834 (w), 773 (w), 756 (w), 586 cm−1 (w); Anal. Calcd
for C7H2I4N6O4 (741.63): C 11.33, H 0.27, N 11.33. Found: C 11.45,
H 0.341, N 11.45.
Financial support of the Office of Naval Research (N00014-16-
1-2089), and the Defense Threat Reduction Agency (HDTRA
1-15-1-0028) is gratefully acknowledged. The M. J. Murdock
Charitable Trust (No. 2014120) is thanked for funds
supporting the purchase of a 500 MHz NMR.
REFERENCES
4.5. Ammonium 2,6-Diiodo-3,5-dinitro-9H-dipyrazolo[1,5-
a:5′,1′-d][1,3,5]triazin-4-ide (4). Compound 3 (741 mg, 1 mmol)
was dissolved in 10 mL of DMSO and aqueous ammonia (10 mL)
was added slowly at room temperature. Then the mixture was heated
at 120 °C in a sealed tube. After 8 h, the mixture was cooled to room
temperature and was blown dry by air. Water (30 mL) was added to
the system giving rise to an orange-red precipitate. It was filtered,
washed with cold water, and dried in vacuo to obtain 370 mg of
orange-red solid. Yield: 70%; Td(onset) = 325 °C; 1H NMR (300 MHz,
DMSO-d6, δ): 7.08 (s, 4H), 6.06 (s, 2H); 13C NMR (75 MHz,
DMSO-d6, δ): 145.56, 120.83, 98.04, 62.14 ppm; IR (KBr): ν = 3420
(w), 3216 (w), 3114 (w), 1525 (s), 1505 (s), 1451 (s), 1436 (s),
1368 (s), 1315 (m), 1216 (m), 1130 (m), 1085 (m), 1024 (m), 996
(m), 946 (m), 891 (w), 811 (w), 770 (m), 761 (w), 715 (w), 630
(w), 414 (w), 403 cm−1 (w); Anal. Calcd for C7H6I2N8O4·DMSO
(569.84): C 18.07, H 2.02, N 18.73. Found: C 18.24, H 1.926, N
18.88.
4.6. 2,6-Diiodo-3,5-dinitro-4,9-dihydrodipyrazolo[1,5-
a:5′,1′-d][1,3,5]triazine (5). To an ice-cold aqueous solution of
hydrochloric acid (1 M, 5 mL), compound 4 (300 mg 0.57 mmol)
was added slowly, while the reaction temperature was maintained at
0−5 °C. The final suspension was stirred at 0−5 °C for 30 min and
was filtered. The pale yellow solid was washed with water and dried in
vacuum to yield 240 mg of compound 5. Yield: >95%; Td(onset) = 323
°C; 1H NMR (300 MHz, DMSO-d6, δ): 6.38 (s, 2H); 13C NMR (75
MHz, DMSO-d6, δ): 135.39, 121.10, 97.83, 62.47 ppm; IR (KBr): ν =
3374 (w), 1613 (m), 1585 (s), 1496 (s), 1480 (m), 1321 (m), 1286
(s), 1239 (m), 1112 (m), 1099 (m), 1035 (w), 892 (m), 817 (w), 775
(w), 760 (w), 716 (w), 627 (w), 617 (w), 524 cm−1 (w); Anal. Calcd
for C7H3I2N7O4 (502.83): C 16.72, H 0.60, N 19.49. Found: C 16.42,
H 0.69, N 19.12.
■
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AUTHOR INFORMATION
Corresponding Author
*E-mail: jshreeve@uidaho.edu.
ORCID
Joseph P. Hooper: 0000-0003-4899-1934
Jean’ne M. Shreeve: 0000-0001-8622-4897
Notes
■
The authors declare no competing financial interest.
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DOI: 10.1021/acs.inorgchem.8b01600
Inorg. Chem. XXXX, XXX, XXX−XXX

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