Synthesis and Geometry of Complex Triorcanoantimony(V) Cations

Abstract

Triorganoantimony(V) cations of the types [R₃SbL₂]⁺² (I),[R₃SbL′]⁺² (II) and [R₃SbL″]⁺¹ (III), where R=CH₃, C₆H₅,p-CH₃C₆H₄, p-C1C₆H₄, p-FC₆H₄ and C₆F₅: L = TU, HMPA, PyO, DMSO; TPPO, TPAO; L′ = bipy and en and L″ = acac, have been isolated in combination of balancing C1O₄. anion(s) and characterized by elemental analyses, molar conductance measurements/ IR and ¹H n.m.r. spectral data. In the solid state IR spectra, a progressive trend towards lower frequency was observed in the characteristic ν(X-O) frequency (X = N, P, S and As) whilst the ν(Sb-O) frequency showed trend towards higher frequency on complexation depending upon the nature of the organic R group bound to Sb. The complexes [R₃SbL₂] [ClO₄]₂ and [R₃SbL′] [C1O₄]₂ behave as 1:2 electrolytes whereas [R₃SbL″][ClO₄] acts as 1:1 electrolyte. IR spectra in dichloromethane suggest the absence of dissociation of these complex cations. Spectroscopic data and solution phase studies conform to the requirement of a trigonal bipyramidal configuration for these complexes. Attempts to prepare the complex [R₃Sb(PyO)₂][ClO₄]₂ were not successful due to hydrolytic instability and it could be isolated only as binuclear oxo-bridge complex, [(R₃Sb(PyO))₂O] [clo₄]₂.