Synonyms: Ferrate(3-),bis[4-[4,5-dihydro-4-[(2-hydroxy-5-nitrophenyl)azo]-3-methyl-5-oxo-1H-pyrazol-1-yl]benzenesulfonato(3-)]-,trisodium; Ferrate(3-), bis[4-[4,5-dihydro-4-[[2-(hydroxy-kO)-5-nitrophenyl]azo-kN1]-3-methyl-5-(oxo-kO)-1H-pyrazol-1-yl]benzenesulfonato(3-)]-,trisodium (9CI); Benzenesulfonic acid,4-[4,5-dihydro-4-[(2-hydroxy-5-nitrophenyl)azo]-3-methyl-5-oxo-1H-pyrazol-1-yl]-,iron complex