Crystalline Ph3SnSiH3 and Ph3SnGeH3 have been prepared for the first time. These air stable molecules are potential model compounds for the design of new IR semiconductors in the emerging Si-Ge-Sn system. Their structure and composition have been elucidated by a wide range of spectroscopic techniques in addition to chemical analysis and single crystal x-ray diffraction. First principles simulations corroborate the structures and provide insight into the relative stability of the two compounds.