The synthesis and characterisation of some Group 14 compounds containing the 2,4,6-(CF3)3C6H2, 2,6-(CF3)2C6H3 or 2,4-(CF3)2C6H3ligands

Abstract

New (aryl)₂ECl₂ and (aryl)ECl₃ compounds [E = Si, Ge or Sn; aryl = 2,4,6-(CF₃)₃C₆H₂ (Ar), 2,6-(CF₃)₂C₆H₃ (Ar′) and/or 2,4-(CF₃)₃C₆H₃ (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, ¹⁹F and (where appropriate) ¹¹⁹Sn 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, ¹⁹F 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).