Synonyms: 3,3'-(Methylenebis((4,6-dihydroxy-3,1-phenylene)azo))((4-hydroxy-5-nitrobenzenesulfonic acid)(2'-hydroxy-5'-nitrobenzenesulfonic acid)-, complex with Fe3+ (1:2);(mu-(3-((5-((2,4-Dihydroxy-5-((2-hydroxy-3-nitro-5-sulphophenyl)azo)phenyl)methyl)-2,4-dihydroxyphenyl)azo)-2-hydroxy-5-nitrobenzenesulphonato(6-)))diiron;Iron, (mu-(2-(hydroxy-kappaO)-3-((5-((2-hydroxy-4-(hydroxy-kappaO)-5-((2-(hydroxy-kappaO)-3-nitro-5-sulfophenyl)azo-kappaN1)phenyl)methyl)-2-(hydroxy-kappaO)-4-hydroxyphenyl)azo-kappaN1)-5-nitrobenzenesulfonato(6-)))di-;Iron, (mu-(2-(hydroxy-kappaO)-3-(2-(5-((2-hydroxy-4-(hydroxy-kappaO)-5-(2-(2-(hydroxy-kappaO)-3-nitro-5-sulfophenyl)diazenyl-kappaN1)phenyl)methyl)-2-(hydroxy-kappaO)-4-hydroxyphenyl)diazenyl-kappaN1)-5-nitrobenzenesulfonato(6-)))di-;Iron, (mu-(3-((5-((2,4-dihydroxy-5-((2-hydroxy-3-nitro-5-sulfophenyl)azo)phenyl)methyl)-2,4-dihydroxyphenyl)azo)-2-hydroxy-5-nitrobenzenesulfonato(6-)))di-