Water-soluble phosphonium salts containing 1,12-dicarba-closo-dodecaborane(12)

The preparation of new water-soluble phosphonium salts containing 1,12-dodeca-closo-dodecaborane(12) (closo-1,12-carborane) for potential use as tumor-targeting agents in Boron Neutron Capture Therapy (BNCT) is described.