We report comprehensive X-ray diffraction and NMR studies of potassium-induced dimerization of heteroleptic triple-decker crown-phthalocyaninates [(15C5)(4)Pc]M(Pc)M(Pc) (1M, M = Y and Tb). Characterization of the crystalline dimer 2(1Y)center dot 4KBPh(4)center dot 12CH(3)CN center dot 10CHCl(3) gave the first structural evidence of the formation of a six-decker structure with four rare earth metal ions perfectly aligned near the symmetry axis. NMR studies of soluble supramolecular dimers 2(1M)center dot 4KOAc provided a spectral-structural model that allowed us to assign the NMR spectra of related complexes with paramagnetic lanthanides and to further evaluate their structure and long-range interaction between the Ln(III) centers in multinuclear tetrapyrrolic complexes. The obtained results are promising for elaboration of new supramolecular magnetic materials.