Structural aspects of copper catalyzed atom transfer radical polymerization

Structural features of copper(I) and copper(II) complexes with bidentate, tridentate and tetradentate nitrogen based ligands commonly used in atom transfer radical polymerization (ATRP) were extensively reviewed and discussed based on several spectroscopic techniques. Complexing ligands included 2,2′-bipyridine (bpy), 4,4′-di(5-nonyl)-2,2′-bipyridine (dNbpy), N,N,N′,N′-tetramethylethylenediamine (TMEDA), N-propyl(2-pyridyl)methanimine (NPrPMI), 2,2′:6′,2″-terpyridine (tpy), 4,4′,4″-tris(5-nonyl)-2,2′:6′,2″-terpyridine (tNtpy), N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA), N,N-bis(2-pyridylmethyl)octylamine (BPMOA), 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA), tris[2-(dimethylamino)ethyl]amine (Me6TREN), tris[(2-pyridyl)methyl]amine (TPMA) and 1,4,8,11-tetraaza-1,4,8,11-tetramethylcyclotetradecane (Me4CYCLAM). Additionally, structures of copper(I) and copper(II) complexes with diethylenetriamine (DETA), triethylenetetramine (TETA), N,N-bis(2-pyridylmethyl)amine (BPMA), tris[2-aminoethyl]amine (TREN) and 1,4,8,11-tetraazacyclotetradecane (CYCLAM) were discussed. The structures were found to depend on the complexing ligand, solvent and temperature.