trithioarsenite

File:SubunitProustite.jpg, a sulfosalt mineral. This picture shows the connectivity of the trithioarsenite trianion to {{chem2|Ag+}} (arsenic is colored violet).]]

Trithioarsenite, also called sulfarsenite, is the trianion {{chem2|AsS3(3−)}}. It is a pyramidal anion, as is typical of other {{chem2|As^{III}X3}} compounds. It is generated by treatment of Arsenic trisulfide with a sulfide:

:{{chem2|As2S3 + 3 S(2−) → 2 AsS3(3−)}}

A fundamental synthetic trithioarsenite is {{chem2|Na3AsS3}}, which features the pyramidal {{chem2|AsS3(3−)}}.{{cite journal |doi=10.1107/S0567740876009898 |title=Structure cristalline de l'orthotrithioarsénite trisodique Na₃AsS₃ |date=1976 |last1=Palazzi |first1=M. |journal=Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry |volume=32 |issue=12 |pages=3175–3177 }}

Thioarsenites are components of many sulfosalt minerals. An example is relatively common mineral proustite, {{chem2|Ag3AsS3}},[http://www.mindat.org Mindat][http://www.webmineral.com Webmineral]Trevelyan B. 1969: The electro-optic effect in proustite. Optical and Quantum Electronics, 1(1), pp. 1969; [https://doi.org/10.1007%2FBF01476785] which is silver(I) trithioarsenite.