Plumbylenes triatomic

III. ELECTRONIC TRANSITIONS IN TRIATOMIC AND TETRAATOMIC GERMYLENES, STANNYLENES AND PLUMBYLENES... 

Some numerical characteristics of the observed electronic transitions in triatomic germy-lenes, stannylenes and plumbylenes of the EX2 and EXY types are collected in Table 1 and Table 2, respectively. Similar data on the triatomic silylenes are included for comparison in these tables. Some molecular constants of germylidene and its silicon analog are compared in Table 3. 

Similarly to the case of the triatomic species (Section III), comparison of absorption maxima of stable germylenes, stannylenes and plumbylenes bearing the same substituents at different divalent atoms of the Group 14 elements (Table 4) does not reveal any... 

Frequencies assigned to the fundamental vibrations of the triatomic germylenes, stannylenes and plumbylenes are collected in Table 7 together with corresponding data on triatomic silylenes for comparison. The vibrational frequencies are sensitive to the environment of the molecule. Therefore, the most precise frequency values measured under each type of condition used (in the gas phase and in different low-temperature inert matrices) by different spectroscopic methods are shown in the table for each of the CAs. Nonfundamental frequencies of triatomic and observed frequencies of polyatomic germylenes, stannylenes and plumbylenes are listed in the text. 

The bond angle in triatomic CAs with the same substituents decreases upon increasing the atomic number of the central atom, although it is worth noting that uncertainties in the determination of bond angles for plumbylenes are extremely large289. In the case... 

Besides the triatomic CAs, the molecular structures have been determined experimentally for only labile silylidene and germylidene, as shown in Table 10. At the same time most of the stable CAs have been characterized by X-ray analysis or by electron diffraction. The available structural data for some stable germylenes, stannylenes and plumbylenes have partly been presented in Section IV. The comprehensive consideration of the geometries of stable CAs is beyond the scope of the present review. 

---