Compound of formula (4) or formula (5), wherein L is a neutral ligand, preferably a nitrogen-containing heterocyclic carbene (NHC) such as carbene containing at least two nitrogen atoms, a cyclic aminoalkyl carbene (CAAC) or a bicyclic aminoalkyl carbene (BICAAC); R1, R3, R4, R5, R6, R7, R8, R9, R10 and R11 are, independently, H, unbranched or branched C1-20 alkyl, C5-9 cycloalkyl, unbranched or branched C1-20 alkoxy, optionally bearing one or more halogen atoms, respectively; or aryl, optionally substituted with one or more of unbranched or branched C1-20 alkyl, C5-9 cycloalkyl, unbranched or branched C1-20 alkoxy, aryl, aryloxy, unbranched or branched C1-20 alkylcarbonyl, arylcarbonyl, unbranched or branched C1-20 alkoxycarbonyl, aryloxycarbonyl, heteroaryl, carboxyl, cyano, nitro, amido, aminosulfonyl, N-heteroarylsulfonyl, unbranched or branched C1-20 alkylsulfonyl, arylsulfonyl, unbranched or branched C1-20 alkylsulfinyl, arylsulfinyl, unbranched or branched C1-20 alkylthio, arylthio, sulfonamide, halogen or N(Ry)(Rz), wherein Ry and Rz are independently selected from H and C1-20 alkyl: RC is H, unbranched or branched C1-20 alkyl.