Non-carbene Complex [RuCl2(PPh3)2(azocane)] as Active Catalyst Precursor for ROMP and ATRP

The novel, non-carbene complex [RuCl 2 (PPh 3 ) 2 (azocane)] ( 1 ) of trigonal bipyramid geometry was synthesized, characterized (CHN elementary analysis, FTIR, EPR, and 31 P NMR), and applied as catalyst precursor for ring opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP). ROMP of norbornene (NBE) resulted in 70% yield at 50 °C in 60 min, with [NBE]/[ 1 ] = 5000, and 15% yield from ROMP of norbornadiene was obtained under the same conditions. ATRP of methyl methacrylate (MMA) resulted in ca. 20% conversion at 85 °C in 9 h, with [MMA]/[ 1 ] = 1000, and increased to ca. 50% in the presence of Al(O i Pr) 3 , with narrower PDI values. With [MMA]/[ 1 ] = 200, ca. 50% yield was obtained at 85 °C in 6 h either in the absence or presence of Al(O i Pr) 3 . ATRP of styrene resulted in 9 and 16% conversion at 110 °C in 7 h in the absence or presence of Al(O i Pr) 3 , respectively, with [St]/[ 1 ] = 1000. Results are discussed considering the five-coordinated molecular geometry of the starting complex and the arrangements required in ROMP and ATRP to initiate the reactions. Graphical Abstract