By reaction of SnI(2), SnI(4), and crown ether (18-crown-6) in the ionic liquid [NMe(n-Bu)(3)][N(Tf)(2)], Sn(3)I(8) x 2 (18-crown-6) is obtained in the form of black, plate-shaped crystals and crystallizes with a monoclinic lattice symmetry. In detail, Sn(3)I(8) x 2 (18-crown-6) is constituted of trigonal-bipyramidal [SnI(5)](-)-anions and [Sn(2)I(3)(18-crown-6)(2)](+)-cations. The cation exhibits an endocyclical coordination of Sn(2+) by the crown ether. Both constituents are linked via long-ranging I-I contacts to form an infinite network. Besides crystal structure analysis, the mixed valence state of tin is evidenced by (119)Sn-Mössbauer spectroscopy.