A convenient route to anionic and cyclic aluminosiloxanes:: crystal structures of [PyH][Al{OSiPh2(OSiPh2)2O}2] and the first twelve-membered organic aluminosilicate Al2Si4O6 ring

The reaction of Al2Cl6 with an excess of Ph2Si(OH)(2) in THF in the presence of pyridine yielded new anionic and cyclic aluminosiloxanes: the structure of the anionic complex is composed of separated pyridinium cations and aluminosiloxane anions dth a tetrahedral arrangement around the Al atom, which is similar to that in natural aluminosilicates; the core of the cyclic aluminosiloxane is a twelve-membered Al2Si4O6 ring in a chair conformation, which contains a Cl group on each of the two Al atoms.