Ruthenium 4,5-diazafluorene Complexes and their Reactivity

The reaction between RuCl2(PPh3)3 and 4,5-diazafluorene (LH) produced the orange, air sensitive RuCl2(LH)(PPh3)2 (1). Exposing this complex to air led to the oxidation of the CH2 group on the central ring of LH to a carbonyl group. RuCl2(LH)(dppb) (3) was synthesized but did not show the same reactivity as complex 1. The reaction between RuHCl(LH)(PPh3)2 (4) and KOtBu produced the purple complex RuH(N2)(L)(PPh3)2 (5), L = deprotonateed 4,5-diazafluorene. Complex 5 heterolytically splits H2 to form RuH2(LH)(PPh3)2 (6), quantitatively. Complex 5 shows C-D bond activation of C6D6 and is air sensitive in the solid state and in solution. Both 1 and 6 were shown to catalyze the hydrogenation of acetophenone. Bis(4,5-diazafluoren-9-yl)methane has been synthesized and fully characterized by 1H NMR, 13C NMR and X-ray crystallography.MAS