Experimental Insights into the Formation, Reactivity, and Crosstalk of Thionitrite (SNO^-) and Perthionitrite (SSNO^-)

Hydrogen sulfide (H₂S) and nitric oxide (NO) are important gaseous biological signaling molecules that are involved in complex cellular pathways. A number of physiological processes require both H₂S and NO, which has led to the proposal that different H₂S/NO⋅ crosstalk species, including thionitrite (SNO^-) and perthionitrite (SSNO^-), are responsible for this observed codependence. Despite the importance of these S/N hybrid species, the reported properties and characterization, as well as the fundamental pathways of formation and subsequent reactivity, remain poorly understood. Herein we report new experimental insights into the fundamental reaction chemistry of pathways to form SNO^- and SSNO^-, including mechanisms for proton-mediated interconversion. In addition, we demonstrate new modes of reactivity with other sulfur-containing potential crosstalk species, including carbonyl sulfide (COS).