Coordination Behavior of a P(4)‐Butterfly Complex towards Transition Metal Lewis Acids: Preservation versus Rearrangement

The reactivity of the P(4) butterfly complex [{Cp’’’Fe(CO)(2)}(2)(μ,η(1:1)‐P(4))] (1, Cp’’’=η(5)‐C(5)H(2) tBu(3)) towards divalent Co, Ni and Zn salts is investigated. The reaction with the bromide salts leads to [{Cp’’’Fe(CO)(2)}(2)(μ(3),η(2:1:1)‐P(4)){MBr(2)}] (M=Co (2Co), Ni (2Ni), Zn (2Zn)) in which the P(4) butterfly scaffold is preserved. The use of the weakly ligated Co complex [Co(NCCH(3))(6)][SbF(6)](2), results in the formation of [{(Cp’’’Fe(CO)(2))(2)(μ(3),η(4:1:1)‐P(4))}(2)Co][SbF(6)](3) (3), which represents the second example of a homoleptic‐like octaphospha‐metalla‐sandwich complex. The formation of the threefold positively charged complex 3 occurs via redox processes, which among others also enables the formation of [{Cp’’’Fe(CO)(2)}(4)(μ(5),η(4:1:1:1:1)‐P(8)){Co(CO)(2)}][SbF(6)] (4), bearing a rare octaphosphabicyclo[3.3.0]octane unit as a ligand. On the other hand, the reaction with [Zn(NCCH(3))(4)][PF(6)](2) yields the spiro complex [{(Cp’’’Fe(CO)(2))(2)(μ(3),η(2:1:1)‐P(4))}(2)Zn][PF(6)](2) (5) under preservation of the initial structural motif.