Synthesis of P 2 C 2 O 2 and P 2 CO via NHC-mediated coupling of the phosphaethynolate anion.

The reaction of the chloroimidazolium chloride salt, [NHC-Cl][Cl], NHC = C{N(2,6-i Pr2 C6 H3 )CH}2 (1) with two equivalents of sodium phosphaethynolate, Na[OCP]·(dioxane)2.5 , results in the formation of NHC-{cyclo-(CO)-P2 -C(O)} (2) and NHC-P2 -C(O)-NHC (3). Notably, in the presence of free NHC ligand, compound 2 converts to compound 3via extrusion of CO at elevated temperatures. The nature of the bonding in these complexes was probed computationally and spectroscopically.