Chapter 24 - Chemistry of Mn and Co Pincer Compounds

Abstract

Since the publication of the first edition of this book on pincer chemistry in 2007, many reports have been made of PCP, PNP, and NNN ligands on first row metals. In this chapter, we look at examples of manganese and cobalt pincer complexes and the types of reaction for which they have found use. Four common classes of pincer ligand are found. Perhaps the simplest is the N(CH2CH2PR2)2 type ligand, where R is typically ipropyl or tbutyl. A well-established ligand is the PCP bis(phosphino)phenyl ligand R2PCH2C6H3CH2PR2, and is pyridine analog (PNP). Finally, extensive studies have appeared using the pyridinediimine (PDI) ligand, RN=2,6-(CH=NR)2NC5H3. Many of these ligands have been found to be active in “noninnocent” behavior, in that the ligand can change its donor properties (X vs L type ligand [ ]). These complexes serve as catalyst (precursors) for a variety of different addition and functionalization reactions. Below, the complexes and their reactivities are sorted on the basis of the type of reaction they exhibit.