Keywords: فرکوکنیل; NHC; N-Heterocyclic Carbene; Grubbs Catalyst I; Structure 1 (Fig. 1); Grubbs Catalyst II; Structure 2 (Fig. 1); Grubbs Catalyst III; Structure 3 (Fig. 1); Hoveyda-Grubbs Catalyst; Structure 4 (Fig. 1); Zhan Catalyst; Structure 5 (Fig. 1); Schrock Catalyst