Experimental

disorder in main residue; R factor = 0.044; wR factor = 0.130; data-to-parameter ratio = 12.8. In the title molecule, C22H21N3, the isoquinoline ring is almost planar [maximum deviation = 0.046 (1) Å] and makes dihedral angles of 52.01 (4) and 14.61 (4) with the pyrazole and phenyl rings, respectively. The phenyl ring and the pyrazole ring are twisted by 44.20 (6) with respect to each other. The terminal C atoms of both of the ethyl groups attached to the pyrazole ring are disordered over two sites with occupancy ratios of 0.164 (7):0.836 (7) and 0.447 (16):0.553 (16). A weak intra-molecular C—H N contact may influence the molecular conformation. The crystal structure is stabilized by C—H contacts involving the phenyl and pyrazole rings, and by – stacking interactions involving the pyridine and benzene rings [centroid–centroid distance = 3.5972 (10) Å]. Related literature For the biological actvity of pyrazoles, see: Huang et al. (1996)