Complexes of the [Re(6)(mu(3)-Se)(8)](2+) core-containing clusters with the water-soluble 1,3,5-triaza-7-phosphaadamantane (PTA) ligand: unexpected ligand protonation and related studies.

Three new complexes of the [Re(6)(mu(3)-Se)(8)](2+) core-containing clusters with the water-soluble trialkylphosphine ligand 1,3,5-triaza-7-phosphaadamantane (PTA), [Re(6)(micro(3)-Se)(8)(PEt(3))(5)(PTA)](SbF(6))(2) (P5PTA, ), [Re(6)(micro(3)-Se)(8)(PEt(3))(5)(PTAH)][Re(6)(micro(3)-Se)(8)(PEt(3))(5)(PTA)](SbF(6))(5) (), and [Re(6)(micro(3)-Se)(8)(PEt(3))(5)(PTAH)](2)(HBr)(SbF(6))(2)Br(4) () have been prepared and structurally characterized. Unexpected protonation of the cluster-bound PTA ligand was observed when coordination of with HgI(2) was attempted, affording compound featuring a protonated PTA ligand, PTAH. Deliberate acidification of with HBr produced compound , and the protonation was investigated by using (31)P NMR spectroscopy. Crystallographic studies revealed distinct structural distortions of the ligand as a result of protonation.