Alkylcycloarsoxanes and alkylcycloarsathianes ambidentate macrocyclic ligands of variable metal-mediated ring size

A comprehensive account of the coordination chemistry of alkylcycloarsoxane s (RAsO)(n), and alkylcycloarsathianes (RAsS)(n) is presented. The former a mbi- and multidentate ligands are characterised by their unique ability to undergo metal-mediated ring expansion to n = 5,6 or 8. Cyclotetramers, -pen tamers and hexamers of their sulphur analogues have also been stabilised as intact species in metal coordination spheres. At elevated temperatures As- S bond cleavage and metal-assisted reassembly afford novel linear and macro cyclic As-S ligands. Cyclotetramers (RAsO)(4) can be employed for the self- assembly of copper(I) halide based porous lamellar and framework coordinati on polymers capable of hosting alkali cations or polar molecules as guests. (C) 1999 Elsevier Science S.A. All rights reserved.