Isolation and characterization of a lithiated pyridine - aggregation in the solid state and in solution

Pyridyllithiums are ubiquitous intermediates used for the electrophilic functionalization of pyridines. In this work, the isolation of a pyridyllithium is reported. Single crystal XRD revealed a dimer in the solid state. In THF solution it was identified as a monomer using DOSY NMR spectroscopy. Calculations showed that the pyridyllithium is a very electron rich pyridine superbase, which may account for its high reactivity. The synthesis, isolation and characterization of the pyridyllithium compound 4-Li-2,6-Mes2py is reported. The crystal structure determination revealed a dimer in the solid state. In solution the pyridyllithium was identified as a monomer.