An improved determination of the crystal structure of hexachlorocyclotriphosphazene (phosphonitrilic chloride)

Abstract

By use of X-ray diffractometer intensity data, the crystal structure of hexachlorocyclotriphosphazene, N3P,CIQ, has been refined to R 0.048 for 1222 reflexions. The phosphazene ring is almost planar but there are small deviations from planarity of up to 0.04 A. The P-N bonds are all equal in length, 1.581 A (u 0.004-0.005 A) and the P-CI bond lengths range from 1.991-1 *995 A (u 0 ~0 0 4 -0 ~0 0 5 A). The mean N-P-N angle in the ring (1 18.4") is significantly smaller than the mean P-N-P angle (1 21.4"). There are only slight deviations from the ideal molecular symmetry DSh (6m2). An analysis of the atomic thermal vibrations shows that at 25' f 2 "C the molecule is undergoing translational vibrations with root-mean-square amplitudes of 0.1 7-0.1 9 A combined with angular oscillations about the molecular axes whose root-mean-square amplitudes are 3.4-3.6".

4,4,4',4',6,6,6',6'-Octachloro-2,2'-dimethyl-2,2'-bi(cyclotriphosphazene), C2H6Cl8N6P6

“…The molecule contains a mean P-Cl bond length of 1.987 (3),~ and a mean exocyclic C1-P-CI bond angle of 100.8 (1) °. These are similar to those reported for (NPCI2)3° (Bullen, 1971). The P(1)-C bond length of 1-781 (4) A and the exocyclic P(I')-P(1)-C bond angle of 104.6 (2) ° are consistent with those found for [N3P3(C6Hs)4CH3] 2 (Ahmed, 1976).…”

Structures of inorganic rings as antitumor agents. II. Structure of the benzene clathrate of 2,2,4,4,6,6-hexa(1-aziridinyl)cyclotri(phosphazene), N3P3az6

“…The endocyclic bond lengths are 1.590 (2) and 1.597 (2)/k, which compare with mean values of 1.589 (2)A in N3P3az6.3CCI 4 (Galy et al, 1980), 1.595 (3)A in the orthorhombic form of N3Paaz 6, and 1.575 (3)A in NaP3CI 6 (Bullen, 1971). The length of the endocyclic bond seems to be well established at 1.593 (1)/~.…”

Competitive formation of spiro and ansa derivatives in the reactions of tetrafluorobutane-1,4-diol with hexachlorocyclotriphosphazene: A comparison with butane-1,4-diol

“…Another approach to the electron-releasing capacity of a geminal pair of substituents is the effect this has on the average value of the P-Cl bonds in the two remaining PCl 2 groups (Table 3) compared with the value for compound (1) of 1.984Å [22]. Although the changes are small in the sequence, (3) 1.990, (12) [35], they are in keeping with the electron-supply properties discussed above.…”

“…Each structure is composed of a cyclotriphosphazene core which, in all cases, exhibits no unusual deviations in geometry from either that of the parent N 3 P 3 Cl 6 structure (CSD code KAGKUY), [22] or from that observed in similar structures in the Cambridge Structural Database [23]. The cyclophosphazene rings are essentially planar, in which the deviation of individual atoms from the N 3 P 3 plane in all the compounds reported here is less than 0.1 Å.…”