In the title salt, C19H25N4O(+)·C24H20B(-), the C=N and C-N bond lengths in the CN3 unit are 1.3327 (8)/1.3364 (9) and 1.3802 (9) Å, indicating double- and single-bond character, respectively. The N-C-N angles are 118.77 (6), 120.29 (6) and 120.81 (6)°, showing only a small deviation of the CN3 plane from an ideal trigonal-planar geometry. The bonds between the N atoms and the terminal methyl C...