Facile Activation and Deoxygenative Metathesis of CO

The rhodium dicarbonyl complex ((NNN)-N-iPr)Rh(CO)(2) (1; (NNN)-N-iPr = 2,5-[(Pr2P)-Pr-i = N(4-(PrC6H4)-Pr-i)](2)N(C4H2)(-)) bearing a monoanionic NNN-pincer ligand was shown to promote the complete C-O bond scission of a carbonyl ligand with the addition of B(C6F5)(3) at ambient temperature. Characterization of the encounter complex ((NNN)-N-iPr)Rh(CO)(2)center dot B(C6F5)(3) (3) by X-ray crystallography provided evidence to suggest a labile phosphinimine acts cooperatively with the borane to activate CO. Isotopic labeling with (CO)-C-13 indicated that a deoxygenative metathesis reaction between P-N and C-O atoms is operative, ultimately affording the CO-derived organic product (C6F5)(3)B <-:C N(4-(PrC6H4)-Pr-i). To our knowledge, this work represents only the second example of a mononuclear transition-metal complex facilitating the deoxygenation of carbon monoxide.