Thionitrite (SNO⁻) and Perthionitrite (SSNO⁻) are Simple Synthons for Nitrosylated Iron Sulfur Clusters

Abstract

S/N crosstalk species derived from the interconnected reactivity of H 2 S and NO facilitate the transport of reactive sulfur and nitrogen species in signaling, transport, and regulatory processes. We report here that simple Fe 2 + ions, such as those that are bioavailable in the labile iron pool (LIP), react with thionitrite (SNO À ) and perthionitrite (SSNO À ) to yield the dinitrosyl iron complex [Fe(NO) 2 (S 5 )] À . In the reaction of FeCl 2 with SNO À we were able to isolate the unstable intermediate hydrosulfido mononitrosyl iron complex [FeCl 2 (NO)-(SH)] À , which was characterized by X-ray crystallography. We also show that [Fe(NO) 2 (S 5 )] À is a simple synthon for nitrosylated FeÀ S clusters via its reduction with PPh 3 to yield Roussin's Red Salt ([Fe 2 S 2 (NO) 4 ] 2À ), which highlights the role of S/N crosstalk species in the assembly of fundamental FeÀ S motifs.