N2s2 chelating agents as cys-x-cys biomimics for fe(no) and fe(no)2 complexes

Abstract

Nitric oxide plays an important role in many biological functions. A metallo derivative in biological systems is a protein-bound dinitrosyl iron complex (DNIC), which results from iron-sulfur cluster degradation in the presence of excess NO. Through model complexes I have examined the fundamental properties of a dithiolato-Fe(NO)2 complex, bismercaptoethandiazacyclooctane iron dinitrosyl or (H+bme-daco)Fe(NO)2 as a biomimic of dicysteinate coordination of [Fe(NO)2]. This complex was prepared and fully characterized in my studies. The DNIC moiety is in its oxidized state, {Fe(NO)2}9. Through reaction studies, monitored by IR spectroscopy (H+N2S2)Fe(NO)2 (N2S2 = bme-dach. Bme-pda) has been shown to transfer NO to FeIII in (TPP)FeCl (TPP = meso-tetraphenylporphyrin) as NO-. The remaining mononitrosyl converts into complex (N2S2)Fe(NO). The (N2S2)Fe(NO) complexes (N2S2 = bme-daco, bme*-daco, bme-dach) were prepared by direct reaction of dimeric [(N2S2)Fe]2 and NO gas. The analogous (N2S2)Co(NO) complex (N2S2 = bme-dach) has also been prepared. The series of square pyramidal (N2S2)M(NO) have been studied by cyclic voltammetry and ν(NO) IR spectroscopy.