Syntheses of low-valent tin and germanium compounds with 1,3-functionalized diphosphatrisilanes

The reaction of low-valent tin or germanium compounds with phosphanides can result in different classes of E(II)P (E = Sn, Ge) compounds. The formation of tetrylenes, rings or clusters depends not only on the reaction conditions but also on the phosphorus substituents. Due to their high reactivity and sensitivity to moisture and oxygen a very limited amount of these compounds are known so far. Especially few silicon substituted diphosphatetrylenes are known1. In the case of the cyclic derivatives no stable compound is reported yet.
Similar to their carbon analogues, the diphosphinotrisilanes are expected to offer a wide range of uses in metalorganic synthesis and complex chemistry. The few established, stable diphosphasilane derivatives are compounds of the type (R2P-SiMe2-)2.2 Other diphosphasilanes with backbone lengths of three or more silicon atoms remain, with exception of Me2Si[-Me2Si-PPh2]2,3 unexplored.
The aim of this work is the preparation of 1,3-diphosphatrisilanes, with different residues on the phosphorus, and their reactions with low-valent tin and germanium halides. The products are spectroscopically characterized and the effects of bulkiness of the substituents on the outcome of the reactions are investigated. The experimental characterization is supported by DFT calculations.