The Stability of Cyclic Nitrogen Compounds

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The Stability of Cyclic Nitrogen
Compounds Amanda Lewis, Jennifer Wilcox, and
Nick Kazantzis Department of Chemical
Engineering Worcester Polytechnic
Institute Worcester, MA 01609
Relevance This investigation demonstrated the
application of using theoretical research to
direct experimental research. The example shown
below uses a high density energy material, C2N10,
that could possibly be used for explosives. The
problem is that there is no information known
about the stability of this molecule. To help
understand the stability of the molecule, the
enthalpy of formation was determined through
theoretical research.

• Calculating Theoretical Data
• The software package Gaussian 03 was utilized.
• G3 theory developed by Curtiss et al. was chosen
  as a means to calculate heats of formation. It is
  an improved version of G2, and is more accurate
  when calculating heats of formation. G3 is less
  computationally expensive and time consuming than
  G2, CCSD(T), and QCISD(T) levels of theory due to
  the changing basis sets.

Reaction Schemes 1.) 3N2H4 4C3H3N3 3N2H2
6HN3 6NH3 6CH3N 3C2N10 2.) 3N2H4
8C4H4N2 3N2H2 6HN3 6NH3 6CH3N 4C5H5N
3C2N10 3.)3N2H4 6C4H4N2 3N2H2 6HN3 6NH3
6CH3N 2C6H6 3C2N10 4.) 3N2H4 12C5H5N
3N2H2 6HN3 6NH3 6CH3N 8C6H6 3C2N10
G3 calculates the total energy of a given
molecule through the following equation E0(G3)
EMP4(FC)/6-31G(d) ?() ?(2df,p) ?(QCI)
? ?(HLC) ZPE Where ?() EMP4(FC)/6-31G
MP4(FC)/6-31G(d) ?(2df,p)
EMP4(FC)/6-31G(2df,p) - MP4(FC)/6-31G(d)
?(QCI) EQCISD(T,FC)/6-31G(d) -
MP4(FC)/6-31G(d) ?
EMP2(FU)/G3Large MP2(FC)/6-31(2df,p)
MP2(FC)/6-31G(d) MP2(FC)/6-31G(d)
Now that the reaction schemes had been
determinetd, the G3 total energy equation could
be utilized. Unfortunately, computational
occurred when trying to calculate the enthalpy of
formation of C2N10 and a few adjustments were
made 1.) MP4(FC)/6-31G(d)//MP2(FU)/6-31G(d) ?
MP4SDQ(FC)/6-31G(d) //MP2(FU)/6-31G(d) 2.)
MP4(FC)/6-31G(d) //MP2(FU)/6-31G(d) ?
MP4SDQ(FC)/631G(d)//MP2(FU)/6-31G(d) 3.)
MP4(FC)/6-31G(2df,p) //MP2(FU)/6-31G(d) ?
MP4SDQ(FC)/6-31G(p,d)//MP2(FU)/6- 31G(d) 4.)
QCISD(T,FC)/6-31G(d) //MP2(FU)/6-31G(d) ?
QCISD(T)/6-31G//MP2(FU)/6-31G(d)
Converting from Total Energy to Enthalpy of
Formation
An isodesmic approach was used to convert the
total energies into enthalpies of formation. This
approach conserves the number of bonds on each
side of the reaction.

• Results
• The calculated enthalpies of formation were put
  back into the reaction scheme equations.
• They were then set equal to the same equation,
  but with the known experimental data.
• From the reaction scheme equations, the
  enthalpies of formation of C2N10 are as follows
  1.) 739.042 kcal/mol, 2.) 744.493 kcal/mol, 3.)
  743.444 kcal/mol and 4.) 740.296 kcal/mol,
  respectively, that gives an average value of
  741.819 kcal/mol.

Determining the Reaction Schemes for the
Formation of C2N10

• Identifying usable reference species species
  that are well studied with accurate
  thermochemical data available and contain the
  same bond types as C2N10.
• Problem there are not many well known species
  with the same bond types as C2N10
• Solution species were used that contained other
  bonds types than C2N10 and therefore balance
  species were added. These balance species
  contained the same bond types as extra ones
• Gathering thermochemical data on the reference
  species
• NIST-JANAF thermochemical database was used for
  the majority of the data
• Identifying the species present during the
  reaction
• As seen below in Table 1. a bond matrix was set
  up. Because there is 11 species and only 9 bond
  types, a new 9 x 9 matrix was created. The
  determinant of this new matrix was calculated
  taking into account all of the different
  combinations.
• Out of all of the determinants, only four paths
  were stoichometrically unique.

Applications This type of research can be used
for a number of different things such as a
starting point for experimental work, which will
save a company a lot money, or it can also be
used to protect the researchers from laboratory
hazards of unknown compousnds. This research
could also be implemented in REACH
registration, evaluation, and authorization of
chemicals an initiative created by European
Chemicals Bureau within the European Union. It
would create a safer work place and allow small
to medium sized enterprizes to be on the same
page.
Table 1. The Bond Matrix for the Isodesmic
Reaction Scheme used to Evaluate the An Initio
Enthalpy of Formation of C2H10
Bonds N N N N
N N
C N C - N
N - H C - H
C - C C C Species
C2N10 2
3
1 2
4
0 0
0 0 C6H6
0 0 0
0
0 0
6 3
3 C5H5N
0 0 0
1
1 0
5 2 2 C4H4N2
0
0 1
2 0 0
4
2 1 C4H4N2
0 0 0
2
2 0
4 1 1 C3H3N3
0
0 0 3
3 0
3
0 0 CH3N
0 0 0
1
0 1
2 0 0 N2H2
0
1 0
0 0 2
0
0 0 HN3
1
1 0
0 0 1
0
0 0 N2H4
0 0 1
0
0 4
0 0 0 NH3
0
0 0
0 0
3 0
0 0 - pyridazine - 1,3-diazine
Table 2. G3 Energy Contributions and Total
Energies for Reference Species and C2N10 in
Hartrees Reference Species MP4(FC)/6-31G(d)
?()
?(2df,p) ?(QCI)
? ?(HLC)
ZPE E0(G3) NH3 -56.2897578
-0.0902997 -0.1294505
-0.0823403 -0.0073612
-0.025544 0.036162
-56.589 C6H6 -231.5317459 -0.0140679
-0.015932
-0.0169012 -0.3253073 -0.09579
0.106636 -232.042 C5H5N -247.5529126
-0.0159325 -0.1827884
0.0016899 -0.332379
-0.09579 0.094161 -248.084 o-C4H4N
2 -263.5418548 -0.0169012
-0.183451 0.0034666 -0.3396753
-0.09579
0.080691 -264.094 m-C4H4N2 -263.5768182
-0.0173593 -0.1839439
0.0025901 -0.3398136 -0.09579
0.081767 -264.129 C3H3N3 -279.603
3974 -0.0186248 -0.1853779
0.0031899 0.0031899
-0.09579 0.069467 -280.178 N2H2 -1
10.3333922 -0.0080926 -0.08196
-0.0007504 -0.1293291
-0.038316 0.029317 -110.563 N
2H4 -111.471453 -0.0191261
-0.1096655 -0.0012444 -0.1365662
-0.044702
0.051904 -111.702 CH3N -94.3455203 -0.0079219
-0.0791078
-0.0013048 -0.1213373 -0.038316
0.042294 -94.551 N3H -164.3708911
-0.0105692 -0.1056388
0.0093907 -0.1905183
-0.051088 0.021857 -164.697 C2N10 -
621.838054 -0.0333763 -0.033763
0.8851032 -1.0700452
-0.185194 0.05943 -622.182 du
e to the computational expense of the SPE
calculations for C2N10 the G3 theory was modified
as detailed