The infrared spectra of isomers have been calculated through ab initio method. It has been observed that the simulated spectrum of one of isomers is matching with the available experimental data in literature, while the other isomers are not matching so much. One can easily understand the basic physical properties of by knowing of their vibration and geometric structures with their interrelation between these properties. It is found that the isomeric structures of are very sensitive to electron correlation treatment with basis set that are employed. So the structure of will not calculate from semi-empirical methods such as modified neglect of differential overlap (MNDO) or AM1 for more accuracy. The simulated spectra show different bands that rarely found all bands simultaneously in single experiment.