202 MHz 31P NMR performances

Chiral Configurations of Spirane‐Bridged Cyclotriphosphazenes

“…On the other hand, singly bridged macrocyclic phosphazene compounds (e.g. containing piperazine [5] and diamine [9,10] ) and spermine-bridged cyclotriphosphazene derivatives [6] have disubstituted cyclotriphosphazene rings, which provide multiple stereocenters and the possibility of diastereoisomers. For example, the meso and racemic forms of piperazine-bridged macrocyclic phosphazenes have been separated by column chromatography and characterised by X-ray crystallography and by 31 P NMR spectroscopy [5] [after addition of a lanthanide-containing chiral shift reagent (CSR)].…”

Chiral configurations in cyclophosphazene chemistry

“…Previous work some years ago had shown that the 31 P NMR of two series of diamine-bridged cyclotriphosphazenes, (127, Fig. 22) exhibited two sets of signals in a 1:1 ratio, which was interpreted in terms of different folded conformations of the molecules resulting from intramolecular NH···Cl hydrogen-bonding [160]. There are a number of reasons why this explanation is not a correct interpretation of the NMR data and it is surprising that such hydrogen bonding was thought responsible for stabilising the two conformations in a 1:1 ratio over a wide temperature range.…”

“…0.06-0.09 ppm [21], the similar behaviour observed for lower members of the series of diamine-bridged macrocyclic-cyclophosphazene compounds, (128) Δδ ca. 0.02-0.05 ppm, [161] and for two analogous series of singly-bridged cyclotriphosphazatriene-diamine derivatives (127; denoted as 3n3 and 4n4 series with n = 6,7,8,9) by Labarre et al [160]. Examples of structures of single-bridged cyclophosphazene derivatives giving rise to meso and racemic diastereoisomers; sterogenic properties known for compound 129 [21], but not recognised for compounds 127 [160] and 128 [96,161] …”

Synthesis and characterization of per-substituted spermine-bridged cyclophosphazene derivatives: the first example of syn/anti conformational polymorphism in a bridged cyclophosphazene

“…Bridged compounds such as 1a-1h may exist as syn or anti conformers in the solid state and the first example of syn and anti conformational polymorphism is reported for a bridged cyclophosphazene, viz. for compound 1a.Although numerous fully and partially substituted derivatives of cyclotriphosphazene and cyclotetraphosphazene are known [1], the literature on singly and doubly bridged derivatives is sparse [2][3][4][5], until relatively recently [6-10]. Most bridged cyclophosphazene compounds are based on linking two cyclophosphazene derivatives with linear primary di-amines [2,3,6], polyamines, such as spermidine [4] or spermine [5,9] and with secondary diamines [7,8].…”

“…Although numerous fully and partially substituted derivatives of cyclotriphosphazene and cyclotetraphosphazene are known [1], the literature on singly and doubly bridged derivatives is sparse [2][3][4][5], until relatively recently [6][7][8][9][10]. Most bridged cyclophosphazene compounds are based on linking two cyclophosphazene derivatives with linear primary di-amines [2,3,6], polyamines, such as spermidine [4] or spermine [5,9] and with secondary diamines [7,8].…”