Polymorphism, the ability of a chemical substance to exist in more than one crystal structure, is a subject of intense investigations in the present [1]. Beside the scientific challenge given by this complex phenomenon of solid state chemistry, the polymorphism is one of the most important areas of drug device today. Iminophosphoranes are key intermediates in the synthesis of compounds with biological and pharmacological activity. This study presents the synthesis and structural characterization of two polymorphs of a new iminophosforane [2]. The polymorphic forms have been investigated by infrared spectroscopy, nuclear magnetic resonance, mass spectroscopy, X-ray crystallography and studied through ab initio quantum chemical calculations. The polymorph α crystallizes in monoclinic P21 space group and contains two independent molecules (αI and αII) in the asymmetric unit, while β polymorph crystallizes in orthorhombic Pbca space group and has one molecule in the asymmetric unit. Hirshfeld surfaces and fingerprint plots were generated in order to compare αI, αII and ß molecules. The results show that C-H…O and C-H…π hydrogen-bond interactions have a major importance in the packing motifs of two polymorphs. The calculated lattice energies indicate that polymorph β is slightly more stable than polymorph α.