Tetraphenylarsonium iodide,a new determination

The reported crystal structures of Ph₄P⁺·I⁻ and Ph₄As⁺·I⁻ have been re‐examined. An apparent instance of substitutional dimorphism could not be reproduced and, contrary to an earlier report, tetra­phenyl­arsonium iodide, As(C₆H₅)₄]I or Ph₄As⁺·I⁻, was found to be isostructural with the phosphorus compound. The cation and anion are both located on symmetry sites. The crystal packing involves linear chains of cations in fourfold phenyl embraces.