The inversion of configuration at pyramidal terminal phosphides has been observed by 31P NMR spectroscopy.
[10] Terminal planar phosphido ligands engage in M-P multiple bonding.
Planar phosphido complexes usually have shorter M-P bonds and wider M-P-R angles.
[11] In (C5H5)2Hf(PR2)2, which can be prepared by salt metathesis from hafnocene dichloride, Hf(IV) is bonded to both planar and pyramidal phosphido ligands.
Illustrative of the use of R2PCl-like reagents is the synthesis of a diiron diphosphide:[14] Metal phosphido complexes are intermediates the catalytic hydrophosphinations, which is a route to organophosphorus compound.
Although this methodology has not proven to be of practical value, it offers the potential for producing specialized phosphine ligands.
This P-C bond forming step proceeds through an outer-sphere, Michael-type addition.