Synthesis and properties of new ditertiary stibines based upon o-, m- or p-xylyl and m- or p-phenylene backbones and their complexes with tungsten, iron and nickel carbonyls

Abstract

High yield syntheses for 1,2-, 1,3-, and 1,4-xylyl distibines (1,2-C₆H₄(CH₂SbMe₂)₂, 1,3-C₆H₄(CH₂SbMe₂)₂, 1,4-C₆H₄(CH₂SbMe₂)₂, respectively) from Me₂SbCl (conveniently made in situ from Me₂PhSb and HCl_gas) and the appropriate di-Grignard are reported. The 1,3- and 1,4-phenylene distibines, 1,3-C₆H₄(SbMe₂)₂ and 1,4-C₆H₄(SbMe₂)₂, were made similarly. The new ligands have been characterised by mass spectrometry, ¹H and ¹³C{¹H} NMR spectroscopy, and by the preparation of methiodide derivatives. The crystal structures of 1,4-C₆H₄(CH₂SbMe₂)₂ and [1,3-C₆H₄(CH₂SbMe₃)₂]I₂ have been determined. The synthesis of 1,2-C₆H₄(CH₂SbPh₂)₂ has been achieved similarly in modest yield and the distibine converted into the tetra-iodo-derivative 1,2-C₆H₄(CH₂SbPh₂I₂)₂. The coordination modes available to these ligands have been probed by the synthesis and characterisation of complexes with nickel, iron and tungsten carbonyls. The crystal structure of [{Fe(CO)₄}₂{μ-1,3-C₆H₄(CH₂SbMe₂)₂}] has been determined. The spectroscopic properties of these carbonyl derivatives have been compared with those of complexes of other antimony ligands, and in some cases with diphosphine and diarsine complexes, to probe the electronic properties of the new ligands.