Nucleophilic Functionalization of Activated P in [CpFe(CO)-(η-P)][Al(OR)] with Alcohols R-OH.

The bonding situation in [Fp-P][Al(OR)] (1) (Fp = (CO)CpFe, R = C(CF)) gives rise to an Umpolung of the P 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 P - leading to a variety of P building blocks. With excess of R-OH (R = Me, Et, Ph), the thermodynamically more stable complex salts [Fp-P(H)(OR))][Al(OR)] (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 P building blocks. With stoichiometric amounts of R-OH, [Fp-PH][Al(OR)] (2 a) as well as [HP(OR)][Al(OR)] (2 f) were observed as products. Hence, activation of the P-cage in complex 1 was confirmed.