title: Vibrational spectra of 3,5-diamino-6-chloro-N-(diaminomethylene) pyrazine-2-carboxamide: combined experimental and theoretical studies.
abstract: In this work, the vibrational spectral analysis of 3,5-diamino-6-chloro-N-(diaminomethylene)pyrazine-2-carboxamide(3DCNDPC) was carried out using FT-Raman and FT-IR spectroscopy in the range 4000-50cm(-1) and 4000-500cm(-1) respectively. The experimental spectra were recorded in the solid phase. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT) B3LYP with the standard basis set 6-311++G(d,p). The optimized geometric parameters (bond lengths and bond angles) were compared with experimental values. Normal co-ordinate calculations were performed with the DFT force field corrected by a recommended set of scaling factors yielding fairly good agreement between observed and calculated frequencies. Simulation of infrared and Raman spectra utilizing the results of these calculations led to excellent overall agreement with the observed spectral patterns. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The stability of the molecule arising from hyper conjugative interactions and the charge delocalization has been analyzed by using Natural Bond Orbital (NBO) analysis. UV-Vis spectrum of the compound was recorded. The calculated HOMO and LUMO energies show that chemical activity of the molecule.
authors.affiliation: Department of Physics, Panimalar Engineering College, Chennai, Tamil Nadu, India.
authors.forename: S
authors.initials: S
authors.lastname: Sakthivel
authors.affiliation: Department of Physics, Presidency College, Chennai, India.
authors.forename: T
authors.initials: T
authors.lastname: Alagesan
authors.affiliation: Department of Chemistry, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
authors.forename: Abdulaziz A
authors.initials: AA
authors.lastname: Al-Saadi
authors.affiliation: Department of Physics, Indira Institute of Engineering and Technology, Thiruvallur, Tamil Nadu, India.
authors.forename: S
authors.initials: S
authors.lastname: Renuga
authors.affiliation: Department of Physics, Sri Venkateswara College of Engineering, Sriperumbudur, India. Electronic address: muthu@svce.ac.in.
authors.forename: S
authors.initials: S
authors.lastname: Muthu
mesh_terms: D003198:Computer Simulation; D008956:Models, Chemical; D008958:Models, Molecular; D011719:Pyrazines / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D011719:Pyrazines
keywords: DFT; FT-Raman; FTIR; NBO; PED