6-Butyl-5-(4-methylphenoxy)-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidin-7(6H)-one

In the title compound, C21H21N5O2, the triazolopyrimidine ring system is essentially planar [maximum displacement = 0.021 (4) angstrom] and forms dihedral angles of 41.17 (9) and 67.99 (8)degrees with the phenyl and benzene rings, respectively. The n-butyl side chains is disordered over two positions with an ccupancy ratio of 0.77:0.23. An intramolecular C-H center dot center dot center dot O hydrogen-bonding interaction stabilizes the molecular conformation. In the crystal, molecules are linked by intermolecular C-H center dot center dot center dot O and C-H center dot center dot center dot N hydrogen bonds into a three-dimensional network. In addition, pi-pi stacking interactions involving the triazole and pyrimidine rings of adjacent molecules are observed, with centroid-centroid distances of 3.545 (1) angstrom.