In this study, we report the crystal structure and optical and electronic properties of (NH 3 (CH 2 ) 7 NH 3 ) 2 Sn 3 I 10 . Due to twinning disorder of single crystal specimens, a combination of single-crystal and synchrotron powder X-ray diffraction are employed to obtain the atomic coordinates of the vacancy-ordered perovskite derivative. From powdered specimens, the optical absorption and photoluminescence behavior are studied. The electrical conductivity, carrier mobility, carrier density, and dielectric permittivity are analyzed with a combination of dark and time-resolved microwave conductivity experiments on the powders. These properties are compared with those of other vacancy-ordered perovskite derivatives, Cs 2 SnI 6 and (CH 3 NH 3 ) 2 SnI 6 . First-principles calculations at the level of HSE06 with spin-orbit coupling reveal an electronic band structure consistent with both the 3D inorganic connectivity and the "defect" nature of the crystal structure, as assessed from the presence of both localized and dispersed states at the band edges. Together, these results highlight the role of ordering vacancies in a perovskite-derived structure: while it prevents spontaneous tin vacancy formation compensated by mobile positive charge carriers at equilibrium; the defect-like states appear to realize rapid non-radiative recombination pathways for photogenerated carriers.