Iminophosphoranes are valuable building blocks in organic, organometallic and coordination syntheses, being key compounds with biological and pharmacological activity. Recently, it has been shown that triclinic (P-1 space group) crystal form of bis(iminophosphorane)ethane (1) represent 1:1 toluene solvate [1], in which the host molecules encapsulate toluene molecule in the cavity of ~230Å3. The solubility and bioavailability of crystalline compounds may strongly depend on the polymorph type or solvate forms therefore we have undertaken the investigation of different crystalline solvates of 1 with the smaller solvent molecules. Five new isomorphous 2:1 clathrate inclusion complexes of 1, Fig.1, with water, ethanol, ethanol/acetonitrile, tetrahydrofurane, and acetone have been synthesized and structurally characterized by X-ray method. All compounds crystallize in the monoclinic C2/c space group, Table 1. The solvent molecule occupies the cavity with the volume only 82-115 Å3. Thus, the size of solvent molecule influences on stoichiometry and the resulting crystalline form.Acknowledgement Authors thanks the bilateral Moldova-Romanian project 16.80013.5007.04/Ro and the Romanian National Authority for Scientific Research and Innovation, CCCDI-UEFISCDI, project PN3-P3-217/24 BM/19.09.2016 1. Micle A. et al. Tetrahedron Letters 50 (2009) 5622–5624.