Metal–ligand
cooperativity is a powerful tool for the activation
of various bonds but has rarely, if ever, been studied with the radioactive
transition metal99Tc. In this work, we explore this bond
activation pathway with the dearomatized PNP complexcis-[99TcI(PyrPNPtBu*)(CO)2] (4), which was synthesized
by deprotonation oftrans-[99TcI(PyrPNPtBu)(CO)2Cl] with KOtBu. Analogous to its rhenium
congener, the dearomatized compound reacts with CO2to
form the carboxy complexcis-[99TcI(PyrPNPtBu–COO)(CO)2] and with H2to form the mono-hydride complexcis-[99TcI(PyrPNPtBu)(CO)2H] (7). Substrates
with weakly acidic protons are deprotonated by the Brønsted basic
pincer backbone of4, yielding a variety of intriguing
complexes. Reactions with terminal alkynes enable the isolation of
acetylide complexes. The deprotonation of an imidazolium salt results
in the in situ formation and coordination of a carbene ligand. Furthermore,
a study with heterocyclic substrates allowed for the isolation of
pyrrolide and pyrazolide complexes, which is uncommon for Tc. The
spectroscopic analyses and their solid-state structures are reported.