The chain-like polynuclear coordination compounds (ZnBr2)(n)(18-crown-6)(2) (n=4, 6, 8, 10) and [Zn5Br9][N(Tf-2)]

The chain-like polynuclear coordination compounds (ZnBr2)(n)(18-crown-6)(2) (n = 4, 6, 8, 10) and [Zn5Br9][N(Tf)(2)] are obtained by reacting ZnBr2, SnBr4 and 18-crown-6 in the ionic liquid [(n-Bu)(3)MeN][N(Tf)(2)] (N(Tf)(2): bis(trifluoromethylsulfonyl)imide). Structurally, chain-like anionic building units with corner-and edge-sharing ZnBr4/Zn(Br,O)(4) tetrahedra of increasing lengths are obtained for (ZnBr2)(n)(18-crown-6)(2). In contrast, [Zn5Br9][N(Tf) 2] exhibits a cationic [Zn5Br9(18-crown-6)(2)](+) building unit with distorted tetrahedral, trigonal-bipyramidal and octahedral coordination of Zn2+. Besides the coordination of Zn2+ to Br-, Zn2+ is partially coordinated by 18-crown-6 with unusual folding of the crown-ether molecule. In sum, the polynuclear Zn-Br chains can be considered as intermediates between the finite [ZnBr4](2-) anion and the infinite solid (3)(infinity)[ZnBr2]. The addition of the Lewis-acid SnBr4 turned out to be essential for product formation and results in a Br-subtraction from ZnBr2. The coordination compounds are characterized based on structure analysis, thermogravimetry and energy-dispersive X-ray analysis.