The identification of some novel four-membered ring cyclic triphosphenium ions in solution.

The first four-membered ring cyclic triphosphenium ions with carbon substituents (methyl or cyclohexyl) on the outer phosphorus atoms have been identified in solution by P-31 NMR spectroscopy. The cyclohexyl derivative in the presence of [SnCl6](2-) as counterion was stable enough for methylation by methyl triflate to be carried out