The first synthesis of N-substituted tetrahydro-4b,5a,10b,12,13a-pentaazadibenzo[a,h]cyclohepta[1,2,3,4-def]fluorenes has been successfully accomplished via ring transformation reaction of 1,3,5-tricycloalkyl-1,3,5-triazinanes with octahydro-2,2′-biquinazoline in the presence of NiCl₂·6H₂O as a catalyst. The structure was established on the basis of spectral data, mainly 1D (¹H, ¹³C) and 2D (HSQC, HMBC, COSY) NMR spectra, and X-ray diffraction data. Hirshfeld surface analysis was used to study intermolecular interactions in the crystal.