What is the structure of FeC 5H 6+?

Abstract

Calculations performed using both density functional theory (DFT) and the modified coupled-pair functional (MCPF) approach show that FeC 5H 6 + is more stable than HFeC 5H 5 + by about 10 kcal/mol. The ground state of FeC 5H 6 + is a quartet state derived from the 3d 7 occupation of Fe +. For HFeC 5H 5 +, the MCPF approach yields a sextet ground state while DFT yields a quartet; however, these two states are close in energy at both levels of theory.