The synthesis and characterisation of some group 14 compounds containing the 2,4,6-(CF3)(3)C6H2, 2,6-(CF3)(2)C6H3 or 2,4-(CF3)(2)C6H3 ligands.

Abstract

New (aryl)(2)ECl2 and (aryl)ECl3 compounds [E = Si, Ge or Sn; aryl = 2,4,6-(CF3)(3)C6H2(Ar), 2,6-(CF3)(2)C6H3 (Ar') and/or 2,4-(CF3)(3)C6H3 (Ar")] were prepared by reactions of ECl4 with 2 equivalents of ArLi or of a Ar'Li/Ar"Li mixture. The latter gives predominantly the less sterically hindered product Ar"2ECl2 for E = Si or Ge, but Ar'2SnCl2 for the larger central atom. The products were characterised by elemental analysis, F-19 and (where appropriate) Sn-119 NMR spectroscopy, and single-crystal X-ray diffraction for Ar"2SiCl2, ArGeCl3, Ar2GeCl2, Ar"2GeCl2, Ar2SnCl2 and Ar'2SnCl2. For E = Si the synthesis is complicated by Cl/F exchange: besides Ar'2SiCl2 and Ar"2SiCl2, F-19 NMR spectroscopy identified in solution Ar'2SiF2 and Ar'2SiF2. The latter was isolated and its X-ray structure determined. In all compounds, the E atom has a strongly distorted tetrahedral coordination, supplemented by short intramolecular E...F contacts (secondary coordination) with o-CF3 group(s).