Neutral cyanide complexes of iron: Structure and stability

Neutral iron-cyanide complexes have been studied through computational techniques. Fe[CN]n complexes are shown to prefer the cyanide arrangement. Only in the case of Fe[CN] the isocyanide isomer is found to lie slightly below the cyanide isomer. According to the complexation energies, Fe(CN)2 seems to be the main target for possible experimental observation in the gas phase. Mixed complexes with cyanide and cyanogen ligands, Fe(CN)x(C2N2)y, have also been studied. The balance between the stronger ligand character of CN and the preference for low coordination numbers, makes Fe(CN)2, Fe(CN)(C2N2), Fe(CN)2(C2N2), Fe(CN)(C2N2)2, and Fe(CN)2(C2N2)2 the most stable complexes for each stoichiometry.