Stereochemistry of the MX4Y system (M = metal; X = unidentate, Y = bidentate ligand): crystal structure of tetrachloro-[1,2-bis(dimethylarsino)-3,3,4,4-tetrafluorocyclobut-1-ene]rhenium(IV)

Abstract

The title compound has been prepared and its crystal structure determined by the heavy-atom method from diffractometer data; it was refined by full-matrix least-squares to R 0·045 (949 independent observed reflections). Crystals are monoclinic, space group P2₁, a= 8·834(2), b= 16·090(4), c= 6·596(1)Å, β= 109·78(1)°, Z= 2.

Mean distances are: Re^IV–As 2·560(4), Re^IV–Cl 2·32(1)Å. The geometry is considerably distorted from octahedral; this is generally true for [M (bidentate)(monodentate)₄]^x± compounds and a repulsion model has been developed to account for this.