Abstract
Phosphonium salts in solution or bound to solid phase supports interact with the robust [$^{99(m)}$TcO$_4$]− anion in neutral water. This activated form of [$^{99(m)}$TcO$_4$]− represents a source for complexes with the fac-{$^{99(m)}$Tc$^{VII}$O$_3$}+ core, which can be synthesized in high yields and purity.