Phosphido complexes reaction with transition metal

Primary and secondary phosphines can oxidatively add to low-valent transition metal complexes to form phosphido complexes. In contrast to phosphines, metal phosphido complexes are known to undergo fast pyramidal inversion, often on the NMR timescale. Inversion barriers for some platinum complexes, determined by NMR spectroscopy, range from 42 to 67kJmol. As a consequence, phosphido complexes containing other chiral ligands are mixtures of interconverting diastereomers. Reaction of these complexes with electrophiles yields tertiary phosphines and derivatives (Scheme 6.1). 

The bridging phosphide group in bimetallic transition metal complexes appeared to participate in a transformation, rather than behave as an inert spectator ligand. This is particularly obvious in homobimetallic iron and cobalt systems.Mays et al. showed that the reactions of iron-cobalt phosphido-bridged complex 25 with both symmetrical and unsymmetrical alkynes gave five-membered ferracycle-containing compounds, such as 26, in which a CO and an alkyne were inserted regiospecifically into a Co-P bond in 25. Subsequent decarbonylation led to a set of four-membered ferracyclic species 27-30 in low yields. 

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