Theoretical Charge density Proof of N–N weak bonds of RDX Energetic Molecule
The bond topological analysis of Cyclotrimethylene-trinitramine (RDX) energetic molecule has been carried out for the wave function obtained from the ab initio and DFT methods of quantum chemical calculations. The geometrical parameters of all bonds are compared with that of experimental reports. The inclusion of diffuse function in HF basis set levels makes the significant shift of bond critical point towards carbon atoms of C–N bonds. The heteroatomic bond density character is well understood from unequal C-cp and cp-N distances in all C–N bonds. For all the level of calculations, the maximum bond density was found for all N=O bonds, attributes the maximum potential energy V(r). The N–N bond properties are strongly depends upon the equilibrium bond length which clears from charge concentration in shorter N1–N4 bond and charge depletion found in longer N2–N5 and N3–N6 bonding regions. The bond topological analysis of all bonds in RDX molecule resulted that the N–N bond is the weakest among all the other bonds. The weakness of N2–N5 and N3–N6 bonds than N1–N4 bond of RDX has also been analyzed from energy density calculation from various level of theories as an alternate for Laplacian of electron density. From the analysis of CHELPG charges at the MP2 level, the N–N bonds of RDX appears to have a significant ionic nature which attributes strong hyperconjugation effect. The hyperconjugation effect of RDX, due to polarization of N–N bonds, is the additional proof of weak N–N bonds in RDX explosive. The isosurface electrostatic potential shows the electro positive and negative region in the molecule. A large negative potential found at the vicinity of oxygen atoms.
A.K Sikder and Nirmala Sikder, A review of advanced high performance, insensitive and thermally stable energetic materials emerging for military and space applications, J. Hazard. Mater, 112(2004) 1-15.
S. P. Gejji, M. B. Talawar, T. Mukundan , E. M. Kurian, Quantum chemical, ballistic and explosivity calculations on 2,4,6,8-tetranitro-1,3,5,7-tetraaza cyclooctatetraene: A new high energy molecule, J. Hazard,Mat, 36 (2006) A134.
S. F. Coffey, Phonon generation and energy localization by moving edge dislocations, Phys Rev, 24(1981) 6984-6990.
A. B. Kunz and D. R. Beck, Possible role of charged defects in molecular solids, Phys, Rev, B36 (1987) 7580-7585.
S. Zeman, Analysis and prediction of the Arrhenius parameters of low-temperature thermolysis of nitramines by means of the 15N NMR spectroscopy, Thermochim. Acta, 121 (1999) 333.
G. A. Olah, D. R. Squire, Chemistry of Energetic Materials, Academic Press, San Diego (1991).
S. Borman, Advanced energetic materials emerge for military and space applications, Chem, Eng, News, 72 (1994) 18.
S. Zeman, Some predictions in the field of the physical thermal stability of nitramines, Thermochim, Acta, 302 (1997) 11.
A. K. Sikder, G. Maddala, J. P. Agraval and H. Singh, Important aspects of behaviour of organic energetic compounds: a review, J. Hazard, Mater, 84(2001) 1-26.
K. Y. Lee , M. D. Coburn, 3-nitro-1,2,4—triazol-5-one, a less sensitive explosive, Los. Alamos. Report LA-10302-MS, (1985).
K. Y. Lee, L. B. Chapman and M. D. Coburn, 3-Nitro-1,2,4-triazol-5-one, a less sensitive explosive, J. Energ, Mater, 5 (1987) 27-33.
S. J. Smith , B. T. Sutcliffe, The development of Computational Chemistry in the United Kingdom, Reviews in Computational Chemistry, 10 (1997) 271.
J. K. Labanowski, J. W. Andzelm, (Eds), Density Functional Methods in Chemistry. Springer, New York, (1991).
R. G. Parr , W. Yang, Density Functional Theory of Atoms and Molecules, Oxford, New York, (1989).
F. W. Biegler-Konig, R. F. W. Bader and T. J. Ting-Hau, Calculation of the average properties of atoms in molecules. II, J. Comput. Chem, 3(1982) 317-328.
R. F. W. Bader, Atoms in Molecules, A Quantum Theory, Clarendon Press, Oxford (1990).
C. Dieter , E. Kraka, A Description of the Chemical Bond in Terms of Local Properties of Electron Density and Energy, Croatica Chemica Acta, 57 (1984) 1259-1281.
D. V. Korol’kov, Virial theorem and the chemical bond phenomenon, J. Struct. Chem, 33 (1992) 335- 342.
M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, J. A. Montgomery, Jr. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. P. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratchian, J. B. Cross, Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, P. Y. Ayala, Morokuma, G. A. Voth, P. Salvador, J. J. Dannenberg, V. G. Zakrzewski, S. Dapprich, A. D. Daniels, M. C. Strain, O. Farkas, D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. V. Ortiz, Q. Cui, A. G. Baboul, S. Clifford, J. Cioslowski, B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. L. Martin, D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen, M. W. Wong, C. Gonzalez , J. A. Pople, Gaussian, Inc., Pittsburgh PA, (2003).
A. R. Leech, Molecular Modelling, Longman, Essex, (1997).
M. J. Frisch, M. Head-Gordon J. A. Pople, A direct MP2 gradient method, Chem. Phys, Lett, 166 (1990) 275-280.
R. G. Parr, W. Yang. Density Functional Theory of Atoms and Molecules, Oxford University Press, London, (1989).
C. Lee, W. Yang and R. G. Parr, Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density, Phy, Rev, B37(1998) 785-789.
J. P. Perdew, Density-functional approximation for the correlation energy of the inhomogeneous electron gas, Phys Rev, B33 (1986) 8822-8824.
J. Cheeseman, T. A. Keith , R. F. W. Bader, AIMPAC Program Package McMaster University Hamilton, Ontario (1992).
T. Koritsanszky, P. Macchi, C. Gatti, L. J. Farrugia, P. R. Mallinson, A. Volkov and T. Richter, XD-2006. A Computer Program Package for Multipole Refinement and Topological Analysis of Charge Densities and Evaluation of Intermolecular Energies from Experimental or Theoretical Structure Factors, Version 5, 33 (2007).
C. S. Choi and E. Prince, The crystal structure of cyclotrimethylenetrinitramine, Acta Cryst, B28 (1972) 2857-2862.
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