Trithioarsenite, also called sulfarsenite, is the trianion AsS3−3. It is a pyramidal anion, as is typical of other AsIIIX3 compounds. It is generated by treatment of As2S3 with a sulfide:
A fundamental synthetic trithioarsenite is Na3As3, which features the pyramidal AsS3−3.[1]
Thioarsenites are components of many sulfosalt minerals. An example is relatively common mineral proustite, Ag3AsS3,[2][3][4] which is silver(I) trithioarsenite.