Donor properties of triphenylantimony dihalides : preparation and crystal structures of Ph3SbCl2·SbCl3 and [Ph3SbCl][SbCl6]
Abstract
Triphenylantimony dichloride reacts with both antimony(III) and antimony(V) chloride to give addition compounds with the stoicheiometry Ph3SbCl2·SbCl3 and Ph3SbCl2·SbCl5, respectively. X-Ray analysis of the former shows the presence of only weak interactions between the axial chlorine atoms of Ph3SbCl2 and adjacent SbCl3 molecules to give polymeric chains parallel to the a axis. The trigonal bipyramidal geometry of Ph3SbCl2 is little changed; co-ordination about SbIII is square pyramidal with three short (mean 2.337 Å) and two long (mean 3.262 Å) distances. In the SbCl5 compound there is a chloride ion transfer to SbCl5 giving a structure best described in terms of the ionic formulation [Ph3SbCl]+[SbCl6]–. Residual anion–cation interaction is shown by a Cl ⋯ Sb contact of 3.231 Å, and the cation geometry is intermediate between the trigonal pyramidal and tetrahedral extremes. Reactions between Ph3SbX2(X = F, Br, or I) and SbCl3, SbBr3, or SbCl5 are also described.