Chromium Imidate Complexes from the Metathesis-Like Reaction of Phosphinimines and Chromium(0) Fischer Carbene Complexes

The thermal reaction of phosphinimines with alkyl-substituted chromium(0) Fischer
carbene complexes is reported. The process occurs through a metathesis-like reaction to yield
stable chromium imidate complexes. The formation of the azametallacycle 15 from zwitterion
14 is the key to the process. The length of the phosphinimine tether, the electrophilicity of
the imine moiety, and the bulkiness of the imine substituents determine whether the
metathesis process occurs. Only those compounds having short or rigid tethers and
electrophilic and moderately hindered imine groups react with electrophilic Fischer carbene
complexes. Bulkier imines or less electrophilic carbene complexes are unable to form the
key azametallacycles and either decompose or form the condensation products derived from
acid−base reactivity.