Selenonic acid
A selenonic acid is an organic compound containing one or more –SeO3H groups, e.g. benzeneselenonic acid, C6H5SeO3H. Selenonic acids are the selenium analogs of sulfonic acids.
...
Wikipedia
A selenonic acid is an organic compound containing one or more –SeO3H groups, e.g. benzeneselenonic acid, C6H5SeO3H. Selenonic acids are the selenium analogs of sulfonic acids.