The difluorcarbene complex [Fe-2(CO)(8)(mu-CF2)] (2) reacts with AsMe3 under CO substitution to give the mu-CF2 containing complexes [Fe-2(CO)(6)(AsMe3)(2)(mu-CF2)] (4) and [Fe-2(CO)(5)(AsMe3)(3)(mu-CF2)] (5) which have an [Fe-2(CO)(9)]-like structure as shown by X-ray analyses. In the solid state, 4 forms two isomers, 4a and 4b, in a 3 to 1 ratio, which differ in the position of the mu-CF2 ligand; 4a has a local C-2 axis and 4b has C-1 symmetry. The Fe-Fe distances in 4 and 5 are 2.47 angstrom and are the shortest ones found in [Fe-2(CO)(9)]-like compounds. Efforts were also undertaken to replace one or more CO groups in 2 by other ligands, such as N (bpy, phen, pzy, etc.) or P donors (dppe, dppm). With dppm, only the CF2 free complex, [Fe-2(CO)(4)(mu-Ph2PCH2PPh2)(2)(mu-CO)] (6), could be detected and characterized by X-ray analysis. Most of the reactions resulted in the formation of red-brown materials which were insoluble in the usual solvents and which could not be characterized. The use of CH2Cl2 during the attempts to crystallize a product from the reaction of 2 and phen gave [Fe(phen)3]Cl-2 (7) in low yields. For 4 and 5, the electronic structures were analyzed using the atoms in molecules (AIM) theory. No electron density was found between the two iron atoms, and the short contacts can be interpreted in terms of a pi-interaction.