Reactions of TpRu(CO)(NCMe)(Me) (Tp = hydridotris(pyrazolyl)borate) with heteroaromatic substrates: Stoichiometric and catalytic C-H activation

The Ru(II) complex TpRu(CO)(NCMe)(Me) Up = hydridotris(pyrazolyl)borate) initiates carbon-hydrogen bond activation at the 2-position of furan and thiophene to produce methane and TpRu(CO)(NCMe)(aryl) (aryl = 2-furyl or 2-thienyl). Solid-state structures have been determined for TpRu(CO)(NCMe)(2-thienyl) and [TpRu(CO)(mu-C,S-thienyl)](2). The complex TpRu(CO)(NCMe)(2-furyl) serves as a catalyst for the formation of 2-ethylfuran from ethylene and furan. DFT calculations of the C-H activation of furan by {(Tab)Ru(CO)(Me)} (Tab = tris(azo)borate) indicate that the C-H activation sequence does not proceed through a Ru(IV) oxidative addition intermediate.