Synonyms: Cobaltate(6-), ((P,P'-(1,2-ethanediylbis((nitrilo-kappaN)bis(methylene)))tetrakis(phosphonato-kappaO))(8-))-, sodium hydrogen (1:5:1), (OC-6-21)-;Pentasodium cobaltous ethylenedi(nitrilodi(methylenephosphonate));Cobaltate(6-), (((1,2-ethanediylbis((nitrilo-kappaN)bis(methylene)))tetrakis(phosphonato-kappaO))(8-))-, pentasodium hydrogen, (OC-6-21)-;Pentasodium hydrogen (((ethylenebis(nitrilobis(methylene)))tetrakis(phosphonato))(8-)-N,N',O,O'',O'''',O'''''')cobaltate(6-);phosphonate, P,P',P'',P'''-[1,2-ethanediylbis[nitrilobis(methylene)]]tetrakis-, cobalt(2+) sodium salt (1:1:5)