Vibrational (Raman and IR) spectra of the 1:1 complexes of dihalogermylene and dihalostannylene with 1,4-dioxane and PPh
3 have been reported, the structures of the complexes Cl
2Ge·C
4H
8O
2 and Cl
2Ge·PPh
3 updated using high-resolution X-ray method. Quantum-chemistry calculations of the geometry and normal mode frequencies and eigenvectors were carried out for some of the complexes. The results show that in the structure of the polymeric solid complexes of X
2M with 1,4-dioxane, intermolecular coordination X
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M plays a prominent role, whereas the corresponding complexes with PPh
3 are monomeric. In the vibrational spectra of all the complexes, an inversion of symmetric and antisymmetric stretching νXM (X=Cl, Br; M=Ge, Sn) frequencies, found for ‘free’ X
2M
II particles, still persists, suggesting that the X
2M moieties preserve their specifity as carbene analogues also in the complexes.