Matrix Isolation Studies of Group IV Oxides. IV. Infrared Spectra and Structures of PbO, Pb2O2, and Pb4O4

The matrix isolation of lead oxide vapors has led to the characterization by infrared spectroscopy of three prominent vapor species, PbO, Pb₂O₂, and Pb₄O₄. In a nitrogen matrix these molecules have absorption bands at 718.4 cm⁻¹ (PbO), 557.4 and 467.7 cm⁻¹ (Pb₂O₂), and 474.4 and 374.4 cm⁻¹ (Pb₄O₄). With the aid of ¹⁸O substitution, it is shown that the spectra of Pb₂O₂ and Pb₄O₄ are consistent with molecular symmetries V_h and T_d, respectively, and approximate molecular dimensions are obtained: ${\mathrm{Pb}}_2{\mathrm{O}}_2{\mathrm{,\hspace{0.17em}r}}_{\mathrm{Pb}–\mathrm{O}}\text{=2.17\hspace{0.17em}Å,\hspace{0.17em}〈}\mathrm{OPbO}\text{=79°\hspace{0.17em}}{\mathrm{Pb}}_4{\mathrm{O}}_4{\mathrm{,\hspace{0.17em}r}}_{\mathrm{Pb}–\mathrm{O}}\text{=2.27 Å,\hspace{0.17em}〈}\mathrm{OPbO}\text{=81°.}$ Several weaker features were also observed, and these are assigned to additional polymers.