Easy and quantitative access to Fe(II) and Fe(III) di(aryl)alkynylphosphine oxides featuring [Fe(dppe)Cp*] endgroups: terminal PO functionality blocks the dimerisation of the Fe(III) derivatives

A series of paramagnetic di(aryl)alkynylphosphine oxides 3a–c[PF6] featuring an open-shell [Fe(κ2-dppe)(η5-C5Me5)]+ endgroup were obtained by oxidation of their neutral Fe(II) parents 3a–c, themselves obtained in a simple and nearly quantitative fashion from the corresponding Fe(II) metallophosphines 1a–c. The new organometallic radicals were characterised by NMR and ESR and were shown to be perfectly stable in solution, in contrast to species such as 1a–b[PF6] which readily dimerise.