Coordination Chemistry of Phosphinidene Stabilized by Mesoionic N-heterocyclic Carbene and Catalysis.

Abnormal N-heterocyclic carbene-stabilized phosphinidene, a class of low-valent phosphorus compounds, has been recently stabilized by an isolated abnormal NHC. However, its coordination chemistry with various metal ions remained unexplored. Herein, we have explored the coordination chemistry of a mesoionic N-heterocyclic phosphinidene (mNHP,1), stabilized by an abnormal N-heterocyclic carbene (aNHC) with various metals (Cu, Zn, and Sn) to afford trimetallic, bimetallic, and monometallic complexes, respectively. All these complexes were characterized by single-crystal X-ray diffraction studies. We have also explored the catalytic activity of one of these complexes for alkynylation of trifluoromethyl ketones and found that mNHP (1)-bound trimetallic Cu-complex is an excellent catalyst for this reaction with up to 97% isolated yield under low catalyst loading (3 mol%).