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