SYNTHESIS AND CHARACTERIZATION OF A NEUTRAL AND LIPOPHILIC PH(3)PN(99M)TCO(3) COMPLEX

Ph(3)PNSiMe(3) reacts with (TcO4-)-Tc-99m to form an ion pair that is soluble in organic solvents. Heating of the ion pair produces a new Tc -99m species that is neutral and lipophilic and stable in dry toluene for greater than or equal to 2h. Disserving this new complex in 1:1, E tOH:H2O results in conversion of the product back to the ion pair whic h will limit its in vitro and in vivo stability. The chromatographic p roperties of the ion pair and the Tc-99m species produced when heated in toluene are similar to the analogous Re complexes with Ph(3)PNSiMe( 3) which should have the following respective structures: [Ph(3)PNH(2) (+)][(TcO4-)-Tc-99m] and Ph(3)PN(99m)TcO(3). These results indicate th e potential of phosphinimine ligands in formulation of new Tc-99m radi opharmaceuticals, particularly if phosphinimine ligand derivatives are developed that provide substantially improved stability of the respec tive complexes in aqueous solutions.