text: Several strategies exist for avoiding β-hydride elimination. The most common strategy is to employ alkyl ligands that do not have any hydrogen atoms at the β position. Common substituents include methyl and neopentyl. β-Hydride elimination is also inhibited when the reaction would produce a strained alkene. This situation is illustrated by the stability of metal complexes containing norbornyl ligands, where the β-hydride elimination product would violate Bredt's rule.
  Bulky alkyl ligands, such as tert-butyl or trimethylsilyl, may prohibit the hydrogen atom from approaching a coplanar configuration with respect to the metal, and the α and β atoms. If the metal center does not have empty coordination sites, for example by the complex already having an 18-electron configuration, β-hydride elimination is not possible as well.
  In some cases, the coligands can impose geometries that inhibit β-hydride elimination. For the above example, the unwanted β-hydride elimination is prevented by using a diphosphine where the two phosphorus atoms are fixed apart in space. One way of doing this is to use a trans spanning ligand such as Xantphos. As these metal complexes traditionally form square planar geometries, no vacant site cis to the alkyl group can be formed. Hence the β-hydride elimination is prevented. (See trans-spanning ligand.)