Group 16 elements Dimethyl derivatives

The vibrational spectrum of (9) has been determined by laser Raman and IR spectroscopy. It is concluded that the peroxide group contained therein is characterized by a frequency of 722 cm and not 881 cm <84MI 620-01 >. However, a subsequent study on the pair of isotopically different parent cw-fused naphthaleno-trioxanes (28) and (29) and their ew-dimethyl derivatives (30) and (31) reveals strong Raman bands at 816 cm and 897 cm for (28), and at 802 cm and 885 cm for (30) <88HCA992>. These frequencies are attributed to the coupled C—O and O—O stretching modes of the C—O—O element. The strong Raman bands at 789 cm and 876 cm observed for... 

Dialkyl derivatives of elements of the Second sub-Group, namely, zinc, cadmium, and mercury, contain an almost completely covalent metal-carbon bond. These compounds are normal, unassociated liquids with low boiling points e.g., the dimethyl derivative of zinc boils at 46°, that of cadmium at 105.5°, and that of mercury at 92°. 

Table 17.1. Gaseous dihydrogen, dimethyl, and dichloro derivatives of the Group 16 elements E-H, E-C and E-Cl bond distances (in pm) mean bond energies (in kJ mol ) and ZHEH, ZCEC and ZCIECI valence angles (in degrees).

The search for pentaalkyl and -aryl derivatives of the elements of Group V provides a fascinating story, especially because some rather important discoveries have been made along the way. It began in 1862 when Cahours claimed to have prepared pentamethylarsenic from tetramethylarsonium iodide and dimethyl-zinc. In 1896 Lachman attempted to make pentamethylnitrogen by a similar route at that time chemists imaginations were not restricted by such ideas as the octet rule. Schlenk and Holz did isolate a red compound from the reaction... 

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