Structure, Bonding, and Reactivity of Room-Temperature-Stable Lithium Chloride Carbenoids

Electronic
stabilization of the negative charge by a thiophosphinoyl
and pyridyl/quinolyl substituent allows for the isolation of two lithium
chloride carbenoids at room temperature. Molecular structure analysis
by X-ray crystallography and multinuclear NMR spectroscopy reveal
no direct lithium–carbon interaction in the solid state and
in solution. This leads to remarkable thermal stability but also to
a reduced ambiphilic character of the compounds. Thus, properties
typically observed for nonstabilized Li/Cl carbenoids are less pronounced.
Nevertheless, computational studies still show that despite the charge
delocalization within the compound a high negative charge remains
at the carbenoid carbon atom. Preliminary reactivity studies confirm
this nucleophilic character and show that the carbenoids can still
be used as a “carbene” source for the formation of carbene
complexes.