The Raman and IR spectra of the complexes (CO)5CrSnCl2·THF (1), (CO)5WSnCl2·THF (2), (CO)5CrGeCl2·THF (3), (CO)5WGeCl2·THF (4), (CO)5CrSnCl2·2THF (5), and (CO)5WSnCl2·2THF (6) were measured and interpreted using quantum chemical calculations. Complexes 3 and 5 were characterized by X-ray analysis. The stretching vibrations of the CO groups in the spectra of solutions of complexes 1–6 obey the selection rules for C4ν local symmetry. For the complexes containing 0 (type A), 1 (type B), and 2 (type C) THF molecules, a comparison was made of the calculated and experimental M\documentclass[12pt]{minimal}
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$$\end{document}EII bond lengths and energies, as well as the ν(CO) vibrational frequencies. The contribution of the π-component to the M\documentclass[12pt]{minimal}
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$$\end{document}EII bond decreases in the order A→B→C and leads to enhancement of the donor ability of the carbene-like ligand and to a slight elongation and weakening of this bond. An attempt to grow crystals of complex 6 in air unexpectedly resulted in a polynuclear complex [(CO)5WSn(Cl)(μ-OH)2SnCl2(μ-OH)]2·6THF, which was characterized by X-ray analysis and Raman spectroscopy.
