  For a molecular radical to be stable, the environment needs to be inert.
Furthermore, an unpaired electron is less likely to react chemically, when it
is placed in an extended orbital. Here, we use the tip of a scanning tunneling
microscope to abstract one of the pyrrolic hydrogen atoms from phthalocyanine
(H2Pc) deposited on a single layer of molybdenum disulfide (MoS2) on Au(111).
We show the successful dissociation reaction by current-induced three-level
fluctuations reflecting the inequivalent positions of the remaining H atom in
the pyrrole center. Tunneling spectroscopy reveals two narrow resonances inside
the semiconducting energy gap of MoS2 with their spatial extent resembling the
highest occupied molecular orbital (HOMO) of H2Pc. By comparison to simple
density functional calculations of the isolated molecule, we show that these
correspond to a single occupation of the Coulomb-split highest molecular
orbital of HPc. We conclude that the dangling $\sigma$ bond after N-H bond
cleavage is filled by an electron from the delocalized HOMO. The extended
nature of the HOMO together with the inert nature of the MoS2 layer favor the
stabilization of this radical state.
