New types of triple-decker complexes with an organo-substituted P₅ middle-deck were synthesized by the reaction of [Cp∗Fe(η⁴-P₅R)]^- (1a: R = CH₂SiMe₃; 1b: R = NMe₂) with halogeno-bridged transition metal dimers [Cp′′′MX]₂ (M = Cr, Fe, Co, Ni; X = Cl, Br). By oxidation of [(Cp∗Fe)(Cp′′′Co)(μ,η^4:3-P₅CH₂SiMe₃)] 2a with [Cp₂Fe][PF₆], the cationic complex [(Cp∗Fe)(Cp′′′Co)(μ,η^5:4-P₅CH₂SiMe₃)]⁺ was isolated. The electronic structure of the synthesized complexes was elucidated by DFT calculations.