Nickel Polymerization Catalysts with Ylide Steering Ligands - Late Transition Metal Polymerization Catalysis - page 3

1.1.2
Ylide Ligand Properties and Coordination Modes

The above-mentioned features of ylides, together with the ability to form ylide an-
ions, and their ease of synthesis make them exciting and versatile ligands for tran-
sition metal chemistry [8]. Ylides have outstanding potential with respect to the
formation of transition metal-carbon bonds, because a major reaction path for the
decomposition of such moieties, i.e. -H elimination, is blocked by the phospho-

nium group, a significant difference in comparison with simple alkyl complexes
[Eqs. (2) and (3); Fig. 1.1].

2

3

Ylides mostly act as -carbon ligands with practically no back-bonding characteris-

tics. A variety of ylide-metal structural arrangements have been synthetically accom-
plished. The organometallic ylide chemistry (Fig. 1.1) covers most of the d-block and
some f-block as well as main group elements. It includes mono-, di- and trinuclear

Fig. 1.1 Ylide coordination modes.