Abstract

Binary S,N anions, e.g., NSN²⁻ and SSNSS⁻, and related ternary S,N,O anions such as the structural isomers NSO⁻/SNO⁻ and SSNO⁻ are rarely mentioned in inorganic chemistry textbooks, despite the fact that their salts were synthesised and structurally characterised more than 30 years ago. These fundamentally important species and their conjugate acids, e.g. HNSO and HSNO, have been the focus of numerous investigations in recent years in view of their significance in disciplines as diverse as atmospheric chemistry and cell biology. This Tutorial Review provides a consolidated account of the fundamental chemistry including synthesis, spectroscopic characterisation, molecular and electronic structures, and properties of these intriguing species, and compares these aspects of their behaviour with those of isoelectronic sulfur oxides and N,O anions. A final section draws attention to the significance and applications of these simple S–N species in a broader context.