Hydrogen and methyl derivatives of the Lewis-valent elements

4 Hydrogen and methyl derivatives of the Lewis-valent elements 

The bond distances and mean bond energies of the compounds EH4, E=C to Sn and in E(CH3 4, E=C toPb are listed in Table 13.2. The variation of E-C bond distances as the group is descended is shown in Fig. 13.1. 

The structures of two gaseous subvalent alkyls, E[CH(SiMe3)2]2, E = Ge or Sn, Me = CH3, are also known. The Ge-C and Sn-C bond distances are about 8 pm longer than in the tetramethyls, and the ZCEC angles are smaller than tetrahedral. These sunctures are therefore analogous to the structures of the subvalent chlorides. 

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