The condensation reactions between hexachlorocyclotriphosphazatriene (1), N 3 P 3 Cl 6 , and dibenzo-diaza crown ethers (2 and 3) afforded two novel spiro-crypta-phosphazene derivatives (4 and 5). Compounds (4 and 5) have been characterized by elemental analyses, FTIR, 1 H-, 13 C-, 31 P NMR, HETCOR and MS. The structure of crypta-phosphazene (5) has been determined crystallographically. Compounds (4 and 5) are the first examples of the crypta-phosphazene derivatives. The 31 P NMR spectra of compounds (4 and 5) indicate that both of the compounds have anisochrony, possibly because of the stereogenic nitrogen atoms. In compound (5), the pyramidal geometries of four spirocyclic nitrogen atoms give rise to stereogenic properties. The sum of the bond angles around N4, N4A, N5 and N5A nitrogens are 346.2(4), 348.8(3), 347.1(3) and 345.8(4)8, respectively. Compound (5) crystallizes in the P2 1 space group with aZ11.831(2), bZ21.108(2), cZ11.936(1) A ˚, bZ102.70(1)8, VZ2907.9(6) A ˚3, ZZ2 and D x Z1.442 g cm K3 . The absolute structure was determined successfully. There are two molecules in the asymmetric unit. The structure consists of a non-centrosymmetric, non-planar phosphazene ring with a bulky dibenzo-diaza crown ether side group.