hydrogen sulfide sulfonium compound sulfonium sulfonium CAS:18155-21-0 35.08982 RWSOTUBLDIXVET-UHFFFAOYSA-O CHEBI:30488 +1 trihydridosulfur(1+) H3S(+) chebi_ontology 34.99500 H3S+ sulphonium Gmelin:307 H3S [H][S+]([H])[H] sulfanium [SH3](+) InChI=1S/H2S/h1H2/p+1 sulfur hydride onium cation