Halogenation of heterobimetallic triple-decker complexes containing an E5 middle deck (E = P, As)

Abstract

The halogenation of the heterobimetallic triple-decker complexes [(Cp*Fe)(Cp‴Co)(µ,η5:η4-E5)] (E = P (1), As (6), Cp* = η5-C5Me5, Cp‴ = 1,2,4-tri(tert-butyl)cyclopentadienyl) was investigated. Compound 1 has been oxidised to the isostructural ionic compounds [(Cp*Fe)(Cp‴Co)(µ-PX)(µ,η2:η1:η1-P4X4)][Y] (X = I, Y = [I3] (2), X = Br, Y = [FeBr4] (3)) and to the neutral species [(Cp*Fe)(Cp‴Co)(µ-PCl2)(µ,η2:η1:η1-P4Cl4)] (4) and [(Cp*Fe)(Cp‴Co)(µ-PCl2)2(µ,η1:η1-P2Cl3)] (5). Compounds 2, 3 and 4 possess a heterobimetallic nortricyclane-like FeCoP5 core. The oxidation of the heavier homologue 6 with bromine and iodine afforded the homometallic complexes [(Cp‴Co)2(µ,η4:η4-As4X)][FeX4] (X = I (7) and X = Br (9)). With iodine as halogenating agent, the trinuclear monocation bearing an As6 prism as ligand [(Cp*Fe)(Cp‴Co)2(µ3,η4:η4:η4-As6)][FeI4] (8) was additionally isolated. When PCl5 was used as oxidizing agent, the initially folded As5 ligand planarised resulting in the dicationic species [(Cp*Fe)(Cp‴Co)(µ,η5:η5-As5)][FeCl4]2 (10).