Supramolecular variations on a molecular theme: the structural diversity of phosphazenes (RNH)6P3N3 in the solid state

Cyclophosphazenes tethered together via N-ring centres with ortho-, meta- and para-xylylene linkers

“…In addition, 3 features N-HÁ Á ÁN bridges between dications, which is facilitated by the low steric demand of iso-butyl groups in 3 over the more hindering iso-propyl groups in 4 and 5. The parent phosphazenes also exhibit a strong correlation between the steric demand of side groups and the extensiveness of H-bonding networking [5]. The supramolecular structure of 3 exists as 1D ribbons in the solid state, whereas the networks consisting of dications and bromide anions of 4 and 5 form 2-D sheets.…”

“…Refluxing a 2:1 mixture of hexakis (organoamino) cyclotriphosphazene (RNH) 6 P 3 N 3 {R = i-Bu (1), R = i-Pr (2)} [5] and a,a 0 -dibromoxylene in either thf, toluene or chloroform for 24 h leads to exclusive formation of salts [{(RNH) 6 P 3 N 3 } 2 xyl]Br 2 (Scheme 3). The completeness of the reaction is indicated by the sole appearance of an AX 2 signal in the 31 P NMR spectra.…”

“…This could be a consequence of ring N quaternisation, which also affects the bond lengths within the phosphazene rings. The P-N bonds adjacent to the quaternised N centres measure on average 1.69 Å , which is long when compared to the P-N(ring) bond lengths in the parent phosphazenes 1 and 2, which are in the range of 1.60 Å , [5] but very similar to the P-N bonds in cyclophosphazanes, which are regarded as P-N single bonds [6]. The remaining P-N(ring) bonds are less affected by quaternisation (see Fig.…”

Tris(organozinc) Phosphazenates as Templates for Trimeric and Hexameric Zinc Oxide Clusters

“…Compounds 1, 4, and 6 were prepared as described previously. [13] Et 2 Zn was applied as a 1.0 m solution in hexane. NMR spectra were taken from [D 8 ]toluene solutions.…”

Supramolecular Structures of Cyclotriphosphazenes

“…The crystal structures of (RNH) 6 P 3 N 3 (K) show an unprecedented variety of supramolecular network topologies, which is caused by only subtle alterations in the size or shape of R [58]. The amphiphilic molecules feature an equatorial belt of three nitrogen atoms and six NH groups sandwiched between hemispheres of lipophilic substituents R. Hence, phosphazene molecules tend to interact in a ''side-on'' fashion rather than ''face to face'' resulting in some type of lipid-bilayer formation, as illustrated in Scheme 2.…”