“…6.18 , right). Representative materials are RUB-23 [ 145 ], RUB-29 [ 146 ], and RUB-12 [ 147 ]. Apart from these examples of T atoms in spiro-5 units in silicates, there are in all 23 type materials listed in the zeolite framework data base [ 148 ] with spiro-5 units in aluminosilicate, germanate, phosphate, arsenate, etc., microporous frameworks.…”