Unusual Potassium-η2-Aromatic Interactions in the Crystal Structure of the Diphenylarsenide Transfer Reagent, KAsPh2·2(1,4-Dioxane)

Abstract

In attempting the metallation of 1,2-bis(diphenylarsino)ethane, the title compound KAsPh2·2(1,4-dioxane) was obtained and characterised with a single crystal X-ray structure determination. Like the sodium counterpart, which is a monosolvate, NaAsPh2·1,4-dioxane, the complex may be considered as a two-dimensional polymer, the potassium atoms being linked by bridging 1,4-dioxane units, the oxygen atoms of which form a quasi-square planar array about the potassium atom (K–O 2.676–2.839(3) Å). Unlike the sodium complex, in which arsenide bridging is an intrinsic motif in the construction of the polymer, the K⋯As distance here is long (3.4662(10) Å), with the anion being terminal/monodentate, and counterposed in what may be considered a quasi-octahedral coordination sphere, by a trans-approach to two atoms of a neighbouring aromatic ring (K⋯C(ar) 3.361, 3.416(4) Å), extending the polymer in the third dimension.