The chain-like polynuclear coordination compounds (ZnBr2)n(18-crown-6)2 (n = 4, 6, 8, 10) and [Zn5Br9][N(Tf2)]

Dalton Trans. 2013 Oct 7;42(37):13487-94. doi: 10.1039/c3dt51130h. Epub 2013 Jul 30.

Abstract

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)3MeN][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 Zn(2+). Besides the coordination of Zn(2+) to Br(-), Zn(2+) 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)[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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bromides / chemistry*
  • Coordination Complexes / chemical synthesis
  • Coordination Complexes / chemistry*
  • Crown Ethers / chemistry*
  • Models, Molecular
  • Zinc Compounds / chemistry*
  • alpha-Tocopherol / chemistry*

Substances

  • Bromides
  • Coordination Complexes
  • Crown Ethers
  • Zinc Compounds
  • 18-crown-6
  • alpha-Tocopherol
  • zinc bromide