Transition metal compounds phosphido

Phosphorus magnetic shielding tensors, general phosphido ligands in transition metal complexes, 1, 472 Phosphorus(III) mercury compounds, preparation, 2, 425-426 Phosphorus—metal complexes, characteristics, 2, 34 Phosphorus—nitrogen-containing rings, chromium carbonyl link, 5, 225... 

There are a range of nitrido, phosphido, carbido, and related complexes with metal metal bonds see Cluster Compounds InorganometalUc Compounds Containing Transition Metal... 

As described in Chapter 2, phosphines have sufficiently large barriers to inversion that phosphines with three different substituents can be resolved. In contrast, the inversion of configuration at phosphorus in metal-phosphido complexes tends to occur near room temperature. In imsaturated transition metal complexes, a vacant acceptor orbital stabilizes the planar transition state. This effect is shown by the interconversion between pyramidal structures through a planar transition state, like the one shown in Equation 4.101 and formed during inversion of related compounds. - In saturated middle and late transition metal complexes, inductive effects explained below destabilize the groimd state and lead to lower barriers to inversion. The presence of an ancillary planar phosphide or amide ligand can contribute to a low barrier by accepting the lone pair from a p)Tamidal phosphide, as in Equation 4.101. 

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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