Synthesis and RCM Activity of [(NHC)(NHC_ewg)RuCl₂(3-phenylindenylid-1-ene)] Complexes

[(NHC)RuCl2(3-phenylindenylid-1-ene)(py)] (1) serves as a convenient starting material for the synthesis of [(NHC)(NHCewg)RuCl2(3-phenylindenylid-1-ene)] complexes 3a−3g utilizing [AgI(NHCewg)] complexes (2) as NHC transfer reagents. The respective complexes 3 display excellent activities in RCM reactions leading to tetrasubstituted olefins. The most active precatalyst, 3f, is characterized by 3,4-dichloro and N,N′-diethyl substituents and can be obtained in 94% isolated yield. The redox potentials of complexes 3 and the crystal structure of 3g (3,4-dichloro and N,N′-diisopropyl substituents) were determined.