Cuprate(4-), [μ3-[7-[[6-[[4'-[(4,5-dihydro- 3-methyl-5-oxo-1-phenyl-1H-pyrazol-4-yl)azo ]-3,3'-dihydroxy[1,1'-biphenyl]-4-yl]azo]-1,5-dihydrox y-7-sulfo-2-naphthalenyl]azo]-8-hydroxy-1,3 ,6-naphthalenetrisulfonato(10-)]]tri-, tetrapotassium