text: Although the most common class of pincer ligands features PCP donor sets, variations have been developed where the phosphines are replaced by thioethers and tertiary amines.  Many pincer ligands also feature nitrogenous donors at the central coordinating group position (see figure), such as pyridines.
  An easily prepared pincer ligand is POCOP. Many tridentate ligands types occupy three contiguous, coplanar coordination sites.  The most famous such ligand is terpyridine (“terpy”). Terpy and its relatives lack the steric bulk of the two terminal donor sites found in traditional pincer ligands.
  Metal pincer complexes are often prepared through C-H bond activation.
  Ni(II) N,N,N pincer complexes are active in Kumada, Sonogashira, and Suzuki-Miyaura coupling reactions with unactivated alkyl halides.