The Ammonium purpurate, with the CAS registry number 3051-09-0 and EINECS registry number 221-266-6, has the IUPAC name of Ammonium 2,6-dioxo-5-[(2,4,6-trioxo-5-hexahydropyrimidinylidene)amino]-3H-pyrimidin-4-olate. It is also known as Murexide, and it is the ammonium salt of purpuric acid. It is a kind of reddish purple powder in its dry state, and slightly soluble in water. The molecular formula of this chemical is C₈H₈O₆N₆.

Preparation of Ammonium purpurate: It can be prepared by heating alloxantin in ammonia gas to 100°C, or by boiling uramil (5-aminobarbituric acid) with mercury oxide.

Uses of Ammonium purpurate: Its color purpurate ranges from yellow in strong acidic pH through reddish-purple in weakly acidic solutions to blue-purple in alkaline solutions. Because of this property, it is used as in analytical chemistry as a complexometric indicator for complexometric titrations, most often of calcium ions, but also for Cu, Ni, Co, Th and rare earth metals. And it is also used as a colorimetric reagent for measurement of calcium and rare earth metals.

You can still convert the following datas into molecular structure:
(1)SMILES: c1(c([nH]c(=O)[nH]c1=O)[O-])\N=C1\C(NC(=O)NC1=O)=O.[NH4+]
(2)InChI: InChI=1/C8H5N5O6.H3N/c14-3-1(4(15)11-7(18)10-3)9-2-5(16)12-8(19)13-6(2)17;/h(H2,10,11,14,15,18)(H3,12,13,16,17,19);1H3