Site-selective coordination behaviour of the Py2P–-anion: the N–C–P-allylic system as σ- and π-donor in [(PMDETA)Cs{(μ-PPy)Py}]2 and as a μ2-σ-phosphorus-donor in [{Cp(CO)2Fe}2{(μ-P)Py2 }][BMe4]Dedicated to Professor Siegfried Hünig on the occasion of his 80th birthday.

Abstract

The coordination flexibility of the ambidentate Py₂P^–-anion (Py = 2-pyridyl) spans the wide range from σ-all-nitrogen chelation to hard organometallic moieties, σ-phosphorus μ₂-bridging in dinuclear iron complexes to π-N,C,P heteroallyl coordination to the soft caesium.