Binuclear methylene and difluoromethylene iron carbonyls: A density functional theory study

► The energetically low-lying structures of CX2Fe2(CO)8 (X = H, F) have been characterized by density functional theory. ► CH2Fe2(CO)8 has isomers with and without bridging CO groups in equilibrium similar to Co2(CO)8. ► A higher energy (CH2CO)Fe2(CO)7 structure is found with a bridging ketene ligand. ► Terminal CF2 groups are found in higher energy CF2Fe2(CO)8 structures.