1
Ab initio RHF and density functional B3LYP and B3PW91 study of
4-(4-phthalimidophenyl)-1, 2, 4-triazolidine-3, 5-dione
H. Nasr-Isfahani *a and Z. Kalantar a
a Department of Chemistry, Shahrood University of Technology, Shahrood, Iran.
*[email protected] , [email protected]
Introduction
Urazole is the common name of 1,2,4-triazolidine-3,5-dione. It is a five-member heterocycle which has tri nitrogen atoms and two non neighboring carbonyl groups. The derivatives of urazole are called as urazoles. Urazoles are reported to possess herbicidal activity against weeds [1]. In addition, urazoles are shown to be useful as insecticides [2].
The effectiveness of urazoles as antifungal agents against Pellicularia sasakii and Cocliobolus miyabeanus strains has also been described [3]. In biomedical research, urazole has been employed as a template for the syntheses of triazaprostaglandin analogues [4].
Research efforts, mainly from Hall and co-workers, have also demonstrated the antineoplastic activity, hypolipidemic, antiinflammatory, and antidepressant effects of the urazole derivatives [5]. Further exploration of urazoles and thiourazoles as useful therapeutic agents requires ready access to these classes of heterocycles.
Recently, 4NPPU (C16H10N4O4), 4-(4-(N-phthalimido)phenyl) urazole is synthesized for the first time [6]. Since, this molecule may use as a two functional monomer for preparation of thermoplastic polymers, the study of its structure and determine of its characteristics can help us to design new polymers. In this work, the molecular structure of 4NPPU has been studied employing quantum computational ab initio and DFT methods. The structural formula of 4NPPU used in this study is demonstrated in fig. 1.
H O O
N N N
N
H O O
Urazole Ring
Phenyl Ring
Imide Ring
Figure 1. The structural formula of 4NPPU
2 Method
The structure was fully optimized without any symmetry limitation using RHF, B3LYP and B3PW91 methods using 6-31G** basis set. All calculations were performed using the Gaussian 98 package. This study confirmed that two stable form of molecule exists (Cs symmetry). A large number of starting geometries were used in this study, all of which converged to the same Cs geometries. In these two forms, urazole and imide rings rotated relative to phenyl ring with the same torsion angle and depend on direction of rotation, exhibited cross (fig. 2) and star (fig. 3) structures.
a b
Figure 2. Cross structure for 4NPPU from two views, a) front view and b) side view
a b
Figure 3. Star structure for 4NPPU from two views, a) front view and b) side view
The energy differences between two structures are negligible. Also, the quantum chemical calculations confirms that a ring torsion for five-member urazole so that the hydrogen atom attached to N(1) is behind the plane of the molecule and the hydrogen atom attached to N(2) is in front of the plane of the molecule see figs 2 and 3. This ring torsion of urazole moiety is correspondence to previous quantum mechanical study on urazol [7]. Nitrogen inversion takes place in urazole moiety similar to nitrogen inversions in other amines. However, the two nitrogen atoms are not independent of one another and that inversion of the two adjacent amine groups must occur simultaneously.
3 References
1. Naohara, T.; Natsume, F.; Ishii, K.; Suzuki, S.; Watanabe, H.; Ikeda, O. Patent JP 61076487, 1986.
2. Ovadia, D.; Peleg, N.; Bracha, P. U.S. Patent 4087534, 1978.
3. Shigematsu, T.; Aizawa, H.; Shibahara, T.; Nakazawa, M.; Tomita, M.; Tsuda, M. Patent JP 53018571, 1978.
4. Adams, D. R.; Barnes, A. F.; Cassidy, F.; Thompson, M. J. Chem. Soc., Perkin Trans. 1 1984, 2061-2067.
5. Hall, I. H.; Wong, O. T.; Simlot, R.; Miller, M. C., III.; Izydore, R. A.
Anticancer Res. 1992, 12, 1355-1362.
b) Simlot, R.; Izydore, R. A.; Wong, O. T.; Hall, I. H. J. Pharm. Sci. 1994, 83, 367-371.
c) Hall, I. H.; Simlot, R.; Day, P.; Wong, O. T.; ElSourady, H.; Izydore, R.
A. Pharm. Res., 10, 1206-1211, 1993.
d) Hall, I. H.; Simlot, R.; Izydore, R. A. Arch. Pharm., 328, 5-10, 1995.
6. Nasr-Isfahani, H.; Soldoozi, S. unpublished data.
7. James O. Jensen; spectrochimica acta part A 59, 637- 650, 2003.
4
