Co-ordination of heavier alkali metals by polyimido antimony(III) ligands; syntheses and structures of [{Sb2(NC6H11)4}2M4] (M = Li or Na), Li[{(Me2N)Sb(µ-NC6H11)2}2Sb] and M[{(C6H11NH)Sb(µ-NC6H11)2}2Sb]·2thf (M = K or Rb)

Abstract

The in situ reactions of MCH₂Ph (M = Na, K or Rb) with C₆H₁₁NH₂ in toluene followed by the addition of the appropriate stoichiometric quantity of Sb(NMe₂)₃ gave the new heterobimetallic antimony(III)/alkali metal complexes [{Sb₂(NC₆H₁₁)₄}₂Na₄] and M[{(C₆H₁₁NH)Sb(µ-NC₆H₁₁)₂}₂Sb]·2thf (M = K or Rb). Comparison of the crystal structures of these species with those of the lithium complexes [{Sb₂(NC₆H₁₁)₄}₂Li₄] and Li[{(C₆H₁₁NH)Sb(µ-NC₆H₁₁)₂}₂Sb] reveals that the geometries of these heterobimetallic cages are fundamentally dictated by the rigidity of the [Sb₂(NC₆H₁₁)₄]^2– and [{(C₆H₁₁NH)Sb(µ-NC₆H₁₁)₂}₂Sb]^– anions.