Ligands common multidentate

Abstract During the past decade, atom transfer radical polymerization (ATRP) has had a tremendous impact on the synthesis of macromolecules with well-defined compositions, architectures, and functionalities. Structural features of copper and copper(II) complexes with bidentate, tridentate, tetradentate, and multidentate nitrogen-based ligands commonly utilized in ATRP are reviewed and discussed. Additionally, recent advances in mechanistic understanding of copper-mediated ATRP are outlined. 

Pyridyl donors are common and feature in later sections as part of many multidentate ligands, such as macrocycles. Functionalized pyridyl donors will also be discussed and Section 6.8.4.7 provides examples of the bidentate bipyridyl and phenanthroline complexes. 

Thioether ligand complexes are not very common, however, studies since the mid 1990s have dramatically increased the number of structurally characterized examples. Almost all of these compounds are with chelate or macrocyclic ligands that will stabilize thioether coordination. Mixed donor multidentate ligands containing thioether donors will be discussed in Section 6.8.11. 

Tab. 2 Potential values for mononuclear copper(ll/l) redox couples involving various multidentate ligands in commonly used solvents (all values are presumed to be for 25 °C, jx = 0.1 M, except as noted)...

Three- and four-coordinated Cu(I) compounds are most common however, many one-and two-coordinated Cu(I) ones are also known -. When less than four donor atoms are bound to the copper(I) ion the mononuclear copper(I) enolates tend to oligomerize. To preserve the volatility of the precursors, the oligomerization must be prevented, for example, by using bulky and/or multidentate chelating ligands. In Table 4, Cu(I) enolate coordination compounds which can be used as precursors for CVD of copper are listed. 

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