X-ray data obtained for germylene evidence its monomeric structure, unlike that of stannylene 2, which had been shown previously to form a coordination dimer. Raman spectra of solid and liquid I are identical, whereas the Raman spectra of solid 2 and its solution 2a differ significantly. The spectrum of 2 is complicated and contains the lines corresponding to N -> Sn coordination bonds forming a dinner. The spectrum of 2a is simpler and close to that of monomeric 1, thus pointing to the rupture of the dimer in solution. The UV-vis spectrum of solid 2 exhibits a band corresponding to a transition involving the N -> Sn coordination bonds. Quantum theory of atom's in molecules data, estimate the energy of this bond as similar to 19 kcal/mol. The aromaticity of 1 and 2 with their 10 pi-electron systems including divalent Ge or Sn atoms is confirmed by negative nucleus, independent chemical shift values.