Electronic structure elucidation in oxidized metal–salen complexes

Water-stable [Ni(salen)]-type electrode material based on phenylazosubstituted salicylic aldehyde imine ligand

“…However, several reports on EPR spectroscopy demonstrated the possibility of a Ni II -phenoxyl radical to Ni III -phenolate transition for [Ni(salen)] complexes in highly coordinating solvents or in the presence of coordinating additives like pyridine. [30][31][32][33][34][35] The same transition was observed at low temperature. 36 An additional pro-covalent bond argument consists of prevention of the polymerization process of the nickel salen complex when position 5 (p-position respective to oxygen atom) in the phenyl ring is blocked by a tert-butyl 20 or methyl 6,21 substituent.…”

Recent developments in penta-, hexa- and heptadentate Schiff base ligands and their metal complexes

“…On the other hand, Schiff bases have also been extensively explored for the synthesis of covalent organic frameworks, comprising the two-or three-dimensional porous crystalline structures via the covalent molecular assembly of Schiff base interactions with the layer-by-layer method [36,37]. In addition, most of Schiff bases have the fascinating abilities to coordinate with metallic ions to form their corresponding complexes of main group, transition metal and lanthanide and actinides elements, with their properties being significantly improved by coordinating to the metal ion [38][39][40]. This ability is due to their stereoelectronic and flexible structures leading to highly versatile coordination compounds with a broad scope of applications rranging from subterranean fluid flow tracking [41,42] to bioinorganic and medicinal chemistry [43,44].…”

Exploiting exciton coupling of ligand radical intervalence charge transfer transitions to tune NIR absorption

“…salen) due to their facile and highly modular syntheses which allows for tuning of both the steric and electronic properties. 23 For example, one-electron oxidation of the Ni salen complex 1 ( Fig. 2 ) forms the ligand radical [ 1˙ ] + , which exhibits a sharp, intense IVCT band in the NIR ( E = 4500 cm –1 , ε = 27 700 M –1 cm –1 , Δ ν 1/2 = 650 cm –1 ), indicative of a Class III fully delocalized ligand radical in the Robin–Day classification system.…”