Nucleophilic Functionalization of Activated P₄ in [CpFe(CO)₂-(η¹-P₄)][Al(OR^F)₄] with Alcohols R-OH

The bonding situation in [Fp-P₄][Al(OR^F)₄] (1) (Fp = (CO)₂CpFe, R^F = C(CF₃)₃) gives rise to an Umpolung of the P₄ fragment, which should make it accessible for nucleophiles. To investigate this projected reactivity, the complex was combined with a series of hydroxy-nucleophiles - that all do not react with free P₄ - leading to a variety of P₁ building blocks. With excess of R-OH (R = Me, Et, Ph), the thermodynamically more stable complex salts [Fp-P(H)_x(OR)_3-x)][Al(OR^F)₄] (x=2,1,0) (2b-2d) are formed and show that the phosphonium type pathway is accessible. Quantum chemical calculations display a variety of reaction pathways that all lead very rapidly to the P₁ building blocks. With stoichiometric amounts of R-OH, [Fp-PH₃][Al(OR^F)₄] (2 a) as well as [HP(OR)₃][Al(OR^F)₄] (2 f) were observed as products. Hence, activation of the P₄-cage in complex 1 was confirmed.