In polar solvents such as acetonitrile, PhPCl adopts an ionic phosphonium salt structure, [PhPCl]Cl, whereas in non-polar solvents like diethyl ether it exists as a non-solvated trigonal bipyramidal molecule. Two [PhPCl] species can also adopt an unusual dinuclear ionic structure&mdash;both interacting with a Cl via long Cl–Cl contacts.