An ab initio multiconfigurational CASSCF/CASPT2 approach has been used to calculate the electronic structure of the equilibrium conformations of the FeC2, FeC3 complexes and their anions. We have found cyclic C-2v structures as the ground states for these clusters, except for the FeC3- cluster for which a C-alphav, linear structure is predicted. Formally the electronic structure of the FeCn, (n = 2,3) clusters can be considered as Fe2+Cn2-. The computed adiabatic electron affinities correspond well with the photoelectron spectroscopic data. (C) 2004 Elsevier B.V. All rights reserved.