Mild sp(2)Carbon–Oxygen Bond Activation by an Isolable Ruthenium(II) Bis(dinitrogen) Complex: Experiment and Theory

[Image: see text] The isolable ruthenium(II) bis(dinitrogen) complex [Ru(H)(2)(N(2))(2)(PCy(3))(2)] (1) reacts with aryl ethers (Ar–OR, R = Me and Ar) containing a ketone directing group to effect sp(2)C–O bond activation at temperatures below 40 °C. DFT studies support a low-energy Ru(II)/Ru(IV) pathway for C–O bond activation: oxidative addition of the C–O bond to Ru(II) occurs in an asynchronous manner with Ru–C bond formation preceding C–O bond breaking. Alternative pathways based on a Ru(0)/Ru(II) couple are competitive but less accessible due to the high energy of the Ru(0) precursors. Both experimentally and by DFT calculations, sp(2)C–H bond activation is shown to be more facile than sp(2)C–O bond activation. The kinetic preference for C–H bond activation over C–O activation is attributed to unfavorable approach of the C–O bond toward the metal in the selectivity determining step of the reaction pathway.