• Nonasil (NON): The crystal structure of nonasil synthesized using cobaltocenium [Co(cp)2] + (cp = cyclopentadienyl) cations as OSDA was reported by van de Goor et al. The fluoride anions in nonasil are disordered over two symmetrically equivalent positions that are located in adjacent cages (Figure ). The Si NMR spectrum of this material shows a relatively sharp signal at a chemical shift δiso = -145 ppm at RT, indicating the presence of five-coordinated silicon atoms, and the absence of dynamic disorder. The lack of a dynamic exchange between the two fluoride sites can be understood when considering that these sites are located in different cages. The cages are connected by a 4MR window, through which a fluoride anion cannot pass unless there is a temporary breaking of an Si-O-Si linkage (e.g., in the presence of an acid catalyst). • Mu-26 (STF): A crystal structure refinement of STF-type zeolite Mu-26 without any disorder of fluoride anions and (6R,10S)-6,10-dimethyl-5-azonia-spiro [4.5]decane (DMASD + ) cations was published by Paillaud et al. Si NMR investigations of Mu-26 and of STF-type SSZ-35 show sharp doublets in the range of δiso = -145 to -148 ppm, which were explained as being due to a single [SiO4F] -environment without dynamic disorder at RT. • ITQ-4 (IFR): The structure of as-synthesized ITQ-4 was reported by Bull et al. for a sample synthesized using hydroxybenzylquinuclidinium (BQol + ) as OSDA. The fluoride anions are disordered over two symmetry-equivalent positions in the same cage (Figure ). The Si NMR spectrum of ITQ-4 recorded at T = 298 K shows a broad signal in the range of δiso = -115 to -140 ppm, which is indicative of dynamic disorder. • SSZ-23 (STT): The fluoride anions in as-synthesized SSZ-23 are disordered over three non-equivalent positions within the same cage (Figure ). NMR experiments point to a dynamic behavior of the fluoride anions at RT, which is frozen out upon cooling to 140 K, where a sharp resonance at δiso = -142 ppm appears. Throughout this work, the zeolites will be represented by their framework type code for simplicity (for example, the label NON will be used as a short-hand for nonasil containing fluoride anions and [Co(cp)2] + cations). It is worth emphasising that the four zeolites comprise four different types of fluoride disorder: No disorder (STF), static disorder over equivalent positions in different cages (NON), dynamic disorder over equivalent positions in the same cage (IFR), and dynamic disorder over non-equivalent positions in the same cage (STT).