The prefix "S" indicates that the NO group is attached to sulfur. The  angle is near 114°, reflecting the influence of the lone pair of electrons on nitrogen.
S-Nitrosothiols may arise from condensation from nitrous acid and a thiol:
Other methods for their synthesis. They can be synthesized from  and tert-butyl nitrite (tBuONO) are commonly used.
Once formed, these deeply colored compounds are often thermally unstable with respect to formation of the disulfide and nitric oxide:
S-Nitrosothiols release nitrosonium ions () upon treatment with acids:
and they can transfer nitroso groups to other thiols: