Offene und geschlossene Triferriophosphonium-Salze und Triferriophosphane / Open and Closed Triferriophosphonium Salts and Triferriophosphines

Abstract

The reaction of P(SiMe3)3 with an excess of CpFe(CO)2X (X = Cl, Br) through the action of water gives the triferriophosphonium salt [{CpFe(CO)2}3PH]2FeX4 together with ferrocene as by-product. The cation of the salt can be deprotonated by DBU to afford the unstable triferriophosphine {CpFe(CO)2}3P. Its subsequent realkylation with RX ( R = Me, CH2Ph; X = I, Br) leads to alkyltriferriophosphonium salts [{CpFe(CO)2}3PR]X. Photolysis of [{CpFe(CO)2}3PH]2FeX4 induces the elimination of one CO group, and the CO-bridged and partly closed complex [{μ-CO(CpFeCO)2}{CpFe(CO)2}PH]2FeX4 is formed, the cation of which can also be deprotonated to give the corresponding monobridged phosphine (μ-CO(CpFeCO)2}{CpFe(CO)2}P. Both PH-phosphonium salts undergo a hydrogen-chlorine exchange reaction to give the P-Cl analogues [{CpFe(CO)2}3PCl]2FeX4 and [{μ-CO(CpFeCO)2}{CpFe(CO)2}PCl]2FeX4. The IR and NM R spectra of all species as well as the X-ray structure analyses of the open and closed P-H functional complexes are reported and discussed.