Sn₃I₈·2(18-crown-6): a Mixed-Valent Tin-Crown-Ether Complex

By reaction of SnI2, SnI4, and crown ether (18-crown-6) in the ionic liquid [NMe(n-Bu)3][N(Tf)2], Sn3I8·2(18-crown-6) is obtained in the form of black, plate-shaped crystals and crystallizes with a monoclinic lattice symmetry. In detail, Sn3I8·2(18-crown-6) is constituted of trigonal-bipyramidal [SnI5]−-anions and [Sn2I3(18-crown-6)2]+-cations. The cation exhibits an endocyclical coordination of Sn2+ 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 119Sn-Mössbauer spectroscopy.