X-ray crystallography of the Cl₃[N(CH₃)₂]P₃N₃compounds. I. Crystal structure of the geminal 2,2,4-trichloro-4,6,6-trisdimethylaminocyclotriphosphazatriene

Chiral configurations in cyclophosphazene chemistry

“…The chiral configuration of cyclotriphosphazene derivatives has been constantly determined by X-ray crystallography to confirm the stereogenic properties A c c e p t e d M a n u s c r i p t since 2000 [21]. A detailed survey of structures of cyclotriphosphazenes in the Cambridge Crystallographic Data Base shows that a number of systems, in which the relative distribution of the X,Y substituents leads to pairs of chiral centres, have been described and characterized structurally [36,[42][43][44].…”

“…12 [56]. Crystallographic examples are known for Type I (A ≠ B, A or B can be X or Y), the substituted cyclophosphazene compounds 8b [62], 14 [56], 15 [42], 16 [63], 17a,b [56] and 18a-c [64] and for Type I (A ≠ B), cyclophosphazene compound 19 [65]. Some examples (10a-h [39], 17c,d [56], 20a-d [66]) which did not give crystals suitable for X-ray crystallography or were oils, the racemates were characterized by NMR spectroscopy in conjunction with additions of CSA and/or chiral HPLC.…”

Chiral configurations of spermine-bridged cyclotriphosphazatrienes

“…[1][2][3][4] In addition to geminal and non-geminal replacement paths, 1-4 positional and geometric isomers were isolated and characterised, 5 and in a number of cases confirmed by X-ray crystallography. [6][7][8] Realising that the tetra-coordinated phosphorus atoms in cyclophosphazenes (NPXY) n are pentavalent and potential stereocentres, the possibility of optical isomerism was first discussed in a review 1 in 1962, viz. with two different substituents, X and Y, geminal trisubstituted compounds (type I) and nongeminal trans diand tetra-substituted derivatives (type II) lack all elements of symmetry.…”

Chirality in cyclotriphosphazenes with one stereogenic centre

“…At that time the main focus of attention in the general chemistry of cyclophosphazenes was whether mono-functional reagents reacted with N 3 P 3 Cl 6 or N 4 P 4 Cl 8 via a geminal or non-geminal pathway [1][2][3][4]. Positional and geometric isomers were isolated and characterized [5] and in a number of cases confirmed by X-ray crystallography [6][7][8]. For example, the types of derivatives of cyclotriphosphazenes considered to lack all elements of symmetry were those with one type of substituent in nongeminal trans di-and tetra-substituted derivatives (type I; X ¼ Cl, Y ¼ substitutent or vice versa) or in geminal tri-substituted compounds (type II; X ¼ Cl, Y ¼ substitutent).…”