title: Vibrational and quantum chemical investigation of cyclization of thiosemicarbazide group in 1-benzoyl-4-phenyl-3-thiosemicarbazide.
abstract: 1-Benzoyl-4-phenyl-3-thiosemicarbazide (H3bpt) was treated with acid - base in one sequence and base - acid in other sequence, both of which lead to ring formation of thiosemicarbazide group, giving N-phenyl-5-phenyl-1,3,4-thiadiazol-2-amine (Hppta) in the first case and 4,5-diphenyl-2,4-dihydro-1,2,4-triazole-3-thione (Hdptt) in the second case. The primary (H3bpt) as well as the resulting compounds (Hppta & Hdptt) has been characterized by elemental analyses, NMR, FTIR and Raman spectroscopic techniques. The quantum chemical calculations of the compounds are performed using DFT/B3LYP/6311G(d,p) method for geometry optimizations and also for prediction of the molecular properties. The cyclization is confirmed by disappearance of many bands belonging to the open chain subgroups of H3bpt such as; NH stretching, NH bending, CN stretching, NH puckering, CO stretching etc. The ring formation of 1-benzoyl-4-phenyl-3-thiosemicarbazide (H3bpt) has been further confirmed by the appearance of many bands belonging to the closed ring of thiosemicarbazide in the resulting compounds Hppta and Hdptt.
authors.affiliation: Department of Physics, Banaras Hindu University, Varanasi 221005, India.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Gautam
authors.affiliation: Department of Physics, Banaras Hindu University, Varanasi 221005, India.
authors.forename: Om
authors.initials: O
authors.lastname: Prakash
authors.affiliation: Department of Chemistry, Banaras Hindu University, Varanasi 221005, India.
authors.forename: R K
authors.initials: RK
authors.lastname: Dani
authors.affiliation: Department of Chemistry, Banaras Hindu University, Varanasi 221005, India.
authors.forename: N K
authors.initials: NK
authors.lastname: Singh
authors.affiliation: Department of Physics, Banaras Hindu University, Varanasi 221005, India. Electronic address: ranjanksingh65@rediffmail.com.
authors.forename: Ranjan K
authors.initials: RK
authors.lastname: Singh
mesh_terms: D003500:Cyclization; D004583:Electrons; D008958:Models, Molecular; D008968:Molecular Conformation; D066244:Proton Magnetic Resonance Spectroscopy; D011789:Quantum Theory; D012663:Semicarbazides / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013882:Thiosemicarbazones / Q000737:chemistry*; D014732:Vibration
chemical_list: C000595752:1-benzoyl-4-phenyl-3-thiosemicarbazide; D012663:Semicarbazides; D013882:Thiosemicarbazones; C005151:thiosemicarbazide
keywords: FT-IR; Raman and DFT; Thiadiazole; Thiosemicarbazide; Triazole