Compounds, E2R6 and Similar Species

The E-ligand bond lengths, including those for bulky ligands, match those found in simple mononuclear compounds (Tables 2 and 3). The E—E bond lengths may be compared with values for tetrahedral E in the elements (pm)  

Determinations in Table 15 cover some twenty-five years, and a number of studies suffered from poor crystals, so the initial level of comparison is at the level of a few picometers. In a number of cases, disorder between E and E vitiated detailed discussion, for example of the potentially interesting and well-represented series of ArgEE molecules. For simple ligands, the E—E bond lengths fall into quite tight ranges, slightly shorter than in the elements, and the E—E values interpolate. 

One such study is that of Pannell and colleagues348 who have related the changing crystal structure of the Me3EE Ph3 series to change of E and E. Five of the reported structures (E = E = Si E = Si, E = Ge E = Ge, E = Si) crystallized in a triclinic space group and were isomorphous while the other two (E = Ge, E = Sn and 

A from CHC13 and B from CgHg are homeotypes with 

Intermolecular Sn... Cl links give double chain with distorted trigonal 

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