Pentacoordination in Group 15 ‘onium salts. A room-temperature synthesis of an intramolecularly pentacoordinated tetraarylstibonium salt containing the new polyiodocuprate anion [Cu14I18]4−, and a structural comparison with related pentacoordinated arsoni

Intramolecularly pentacoordinated tetraarylstibonium salts have been obtained at room temperature from the reactions of ortho-iodoarylimino coordination template systems with triarylstibines and copper(I) iodide in acetonitrile, the related bromo- and chloro-arenes being unreactive under these conditions. The X-ray crystal structure of one of these compounds has been determined, and found to contain, as the counter anion, a new type of poly(iodocuprate) species. The structure of the stibonium ion is compared with those of the structurally analogous arsonium and phosphonium cations, thus enabling a detailed comparison of bonding parameters for the heavier Group 15 elements.