Synthesis and Reactivity of Ru(NHC)(dppp)(CO)H2 and Ru(NHC)(dppp)(CO)HF Complexes: C-H and C-F Activation

The hydrido fluorido ruthenium(II) complex [Ru(PPh3)(dppp)(CO)HF] [1, dppp = 1,4-bis(diphenylphosphanyl)propane], which forms upon reaction of [Ru(PPh3)(3)(CO)HF] with dppp, reacts with IMes [1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene] to give the expected carbene-containing hydrido fluorido complex [Ru(IMes)(dppp)(CO)HF] (2), as well as the C-H activated species [Ru(IMes)'(dppp)(CO)H] (3). The formation of the latter product results from the reaction of 2 with a base (IMes or Et3N). Displacement of PPh3 from [Ru(PPh3)(dppp)(CO)H-2) by ICy (1,3-dicyclohexylimidazol-2-ylidene) yields [Ru(ICy)(dppp)(CO)H-2] (7), which upon reaction with Et3N center dot 3HF, gives [Ru(ICy)(dppp)(CO)HF] (8). Thermolysis of 7 with C6F6 at elevated temperature generates 8 and [Ru(ICy)(dppp)(CO)(C6F5)H] (9). The related fluoroaryl complexes [Ru(ICy)(dppp)(CO)(C6F4CF3)H] (10) and [Ru(ICy)(dppp)(CO)(C5F4N)H] (11) are formed upon the room temperature C-F activation of C6F5CF3 and C5F5N by 7, but also by C-H activation of the partially fluorinated substrates p-C6F4HCF3 and p-C5F4HN. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)