High-spin binuclear cyclopentadienyliron chlorides: A density functional theory study

Theoretical studies on the cyclopentadienyliron chlorides Cp ₂Fe₂Cl _n (n = 6 - 1) with iron in the formal oxidation states from +1 to +4 indicate that all the high-spin species are predicted to be the lowest energy structures and they are paramagnetic complexes with magnetic moments between 2.8μ _B and 5.9μ _B. The mixed oxidation state derivatives with odd number of chloride atoms have larger magnetic moments than other species. In addition to Cp₂Fe ₂Cl, which has the largest magnetic moment, these high-spin species have terminal Cp rings and bridging Cl atoms up to a maximum of two bridges. The Cp₂Fe₂Cl₄, Cp₂Fe₂Cl ₃ and Cp₂Fe₂Cl₂ derivatives are predicted to be thermodynamically stable molecules with respect to exothermic reactions for the loss of one Cl atom from Cp₂Fe₂Cl _n . Moreover, the lowest energy Cp₂Fe₂Cl _n (n = 3, 4) derivatives can be derived by the oxidative addition reactions of Cp₂Fe₂Cl _n-2 + Cl₂ → Cp₂Fe₂Cl _n . [Figure not available: see fulltext.]