2021 Volume 79 Issue 12 Pages 1136-1143
The selective formation of linear hydrocarbon chains from C1 monomers is the most intriguing part of the Fischer-Tropsch (FT) reaction. This process has been proposed to involve surface-bound metal carbide, methylidyne, and methylene species as the pertinent monomers and different types of surface hydrocarbyl groups as possible propagating groups. Previous studies on the coupling reactions of these C1 units on homogeneous organometallic systems produced only non-propagating C-C coupling events, leaving the chain propagation models extremely elusive. We have been investigating the chemistry of ruthenium carbide complexes derived from the coordinatively unsaturated dinuclear ruthenium methylene complex [(Cp*Ru)2(µ-NPh)(µ-CH2)] (Cp*=η5-C5Me5). Herein we describe (i) the synthesis of the dinuclear bridging carbide complex [(Cp*Ru)2(µ-NPh)(µ-C)] and (ii) its use for the development of the first homogeneous model of the chain propagation step of the FT reaction. This model reaction is initiated by a C+CH2 coupling and propagates via a consecutive C=CHR+CH2 coupling and hydrogen shifts to form linear C=CH(CH2)nH chains.
