Synthesis and Characterization of (pyNO−)2GaCl: A Redox-Active Gallium Complex

Abstract

Abstract:We report the synthesis of a gallium complex incorporating redox-active pyridyl nitroxide ligands. The (pyNO − ) 2 GaCl complex was prepared in 85% yield via a salt metathesis route and was characterized by 1 H and 13 C NMR spectroscopies, X-ray diffraction, and theory. UV-Vis absorption spectroscopy and electrochemistry were used to access the optical and electrochemical properties of the complex, respectively. Our discussion focuses primarily on a comparison of the gallium complex to the corresponding aluminum derivative and shows that although the complexes are very similar, small differences in the electronic structure of the complexes can be correlated to the identity of the metal.

Molecular S = 2 High-Spin, S = 0 Low-Spin and S = 0 ⇄ 2 Spin-Transition/-Crossover Nickel(II)-Bis(nitroxide) Coordination Compounds

“…Even after the purge of a reductant iodide, the electron-accepting trifluoromethyl group facilitates the reduction of the nitroxide group. The redox ability of the tert-butyl pyridyl nitroxides has been well investigated [161][162][163][164][165] and actually confirmed here. Charge-transfer-triggered switching materials, like valencetautomeric cobalt(II)-SQ compounds [71][72][73] would be a next target of interest.…”

“…We [74]) but very close to that of aminoxylates (1.40-1.42 Å [161][162][163][164][165]). Consequently, the present compounds can be assigned to a reduced form (i.e., phpyNO -).…”

“…The N-O bond length is a fingerprint of the oxidation states of the N-O group, namely, >N + = O, >N-O•, and >N-O -. The N-O bond length in [Ni(phpyNO) 2 ] is 1.397(2) Å, and those in [Ni(phpyNO) 2 ]I 3 are 1.353(3) and 1.366(3) Å, being much longer than a typical N-O length of nitroxides (1.29 Å in a free ligand; 1.30 Å in coordination compounds[74]) but very close to that of aminoxylates (1.40-1.42 Å[161][162][163][164][165]). Consequently, the present compounds can be assigned to a reduced form (i.e., phpyNO -).The nickel(II) ion in [Ni(phpyNO) 2 ] is square planar.…”

Synthesis, Spectroscopic Study and Radical Scavenging Activity of Kaempferol Derivatives: Enhanced Water Solubility and Antioxidant Activity

“…Evaluation of redox reaction between gallium-indium-stannum alloy and redox active species showed that Ga was more easily oxidized by losing electrons than other metals [ 22 ]. When Ga was coordinated with a redox-active ligand, it was able to regulate the electronic nature of the ligand [ 23 ]. 67 Ga (half life 78 h) and 68 Ga (half life 68 min) has been successfully used as imaging agents to assess certain types of tumors, inflammation, and other lesions [ 24 , 25 , 26 , 27 ].…”