Experimental and theoretical investigation of the molecular and electronic structure of 5-(4-aminophenyl)-4-(3-methyl-3-phenylcyclobutyl)thiazol-2-amine.

The title molecule, 5-(4-aminophenyl)-4-(3-methyl-3-phenylcyclobutyl)thiazol-2-amine (C(20)H(21)N(3)S), was prepared and characterized by (1)H-NMR, (13)C-NMR, IR and single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P2(1)/c with a = 9.4350(5) A, b = 11.2796(6) A, c = 18.4170(8) A and beta = 113.378(3) degrees . In addition to the molecular geometry from X-ray experiment, the molecular geometry, vibrational frequencies, gauge including atomic orbital (GIAO) (1)H- and (13)C-NMR chemical shift values and atomic charges distribution of the title compound in the ground state have been calculated using the Hartree-Fock (HF) and density functional method (DFT) (B3LYP) with 6-31G(d) basis set. To determine conformational flexibility, molecular energy profile of the title compound was obtained by semi-empirical (AM1) calculations with respect to two selected degrees of torsional freedom, which were varied from -180 degrees to +180 degrees in steps of 10 degrees . Besides, frontier molecular orbitals (FMO) analysis was performed by the B3LYP/6-31G(d) method.