[M(18-crown-6)X][N(Tf)2] (M: Zn, Co; X: I, N(Tf)2) with unusual crown-ether coordination

[M(18-crown-6)X][N(Tf)2] (M: Zn, Co; X: I, N(Tf)2) is obtained by reacting equimolar amounts of MI2 and 18-crown-6 with an excess of I2 in the ionic liquid [NMe(n-Bu)3]2[N(Tf)2] at 100 °C. The cationic complexes [Zn(18-crown-6)I]+ and [Co(18-crown-6)N(Tf)2]+ exhibit an unusual sevenfold coordination of Zn2+/Co2+ and an unusually twisted 18-crown-6 molecule as a ligand. The structural arrangement is ascribed to the small radius of Zn2+/Co2+, the weakly coordinating features of the ionic liquid and the stabilization of the [Zn(18-crown-6)I]+ and [Co(18-crown-6)N(Tf)2]+ cations via hydrogen-bridge bonding.