122270-18-2Relevant academic research and scientific papers
Studies of the reduction of the nickel(II) complex of 5,10,15,20-tetraphenyl-21-thiaporphyrin to form corresponding nickel(I) complexes
Chmielewski, Piotr,Grzeszczuk, Maria,Latos-Grazyński, Lechos?aw,Lisowski, Jerzy
, p. 3546 - 3552 (2008/10/08)
The divalent nickel complex of 5,10,15,20-tetraphenyl-21-thiaporphyrin NiII(STPP)Cl undergoes one-electron reduction (E1/2° = -0.23 V) to give NiI(STPP). The product of the chemical reduction was isolated and characterized. It reacts with sulfur dioxide to give a paramagnetic five-coordinate NiI-SO2 adduct and coordinates nitrogenous bases (amines, pyridines, imidazoles) to form respective five- and six-coordinate complexes. The nature of the reduced species and its adducts was examined by EPR spectroscopy. The ESR parameters are unique for NiI located in a four-donor macrocyclic environment. Typical values of the g-tensor components are as follows: NiI(STPP), g1, = 2.109, g2 = 2.040, g3 = 2.030; NiI(STPP)(SO2), g1 = 2.187, g2 = 2.087, g3 = 2.075; NiI-(STPP)(1,2-Me2Im), g1 = 2.414, g2 = 2.247, g3 = 2.114; NiI(STPP)(MeIm)2, g1, = 2.237, g2 = 2.198, g3 = 2.136. From the EPR spectra of NiI(STPP) oriented in liquid-crystal nematic glasses, the out-of-plane g-tensor component was determined. Coordination of nitrogenous bases switched the direction of the principal axis from the normal to the thiaporphyrin plane to the in-plane location. EPR parameters can be used to determine the axial ligation of Ni(I) in synthetic and natural (F-430 protein-bound) systems.
