Certain Pd OACs are not easily accessed by traditional oxidative addition of haloarenes to Pd(0) due to competitive thermal decomposition but might potentially be accessible by this ligand exchange process. (NHC)Pd(Ar)X intermediates lacking palladacyclic structures or other stabilizing ligands were selected as a representative test case. These species have not, to our knowledge, been synthesized despite the ubiquity of palladium catalysts coordinated by a single NHC in coupling chemistry. When an admixture of IPr (1,3bis(2,6-diisopropylphenyl)imidazol-2-ylidene) and 2 prepared at -20 °C in CH2Cl2 was analyzed by nanospray ionization-mass spectrometry (nanoESI-MS) with nitrogen protection in the ion source, a signal was observed at m/z = 589 with isotopic distribution (see ESI, Figures ) consistent with a mononuclear complex [Pd(IPr)(C6H4F)] + (Figure ). Presence of this ion supports the notion that the elusive mono-NHC Pd OAC indeed forms rapidly at low temperature. Spectroscopic and computational data provided further insight into the solution state structure of this species.