Matrix Isolation Studies of Group IV Oxides. III. Infrared Spectra and Structures of SnO, Sn2O2, Sn3O3, and Sn4O4

The matrix isolation of vapor phase tin oxides leads to the identification of at least four distinct species: SnO, Sn₂O₂, Sn₃O₃, and Sn₄O₄. Infrared bands for these molecules are observed at 816.1 cm⁻¹ (SnO), 612.6 and 523.2 cm⁻¹ (Sn₂O₂), 761 cm⁻¹ (Sn₃O₃), and 516.5 and 416.3 cm⁻¹ (Sn₄O₄). The spectra of Sn₂O₂ and Sn₃O₃ are consistent with molecular symmetries $V_h$ and $D_{\text{3h}}$ , respectively, while Sn₄O₄ may have either $D_{\text{4h}}$ or $T_d$ symmetry. With the aid of ¹⁸O substitution, and normal coordinate analyses, estimates are given for the molecular dimensions of these species. The concentration changes occurring on diffusion are investigated.