Structure of tetrahydrazinium cyclotetraphosphate: [NH[sub 2]-NH[sub 3]][sub 4]P[sub 4]O[sub 12]

Tetrahydrazinium cyclotetraphosphate, [NH[sub 2]-NH[sub 3]][sub 4]P[sub 4]O[sub 12] (M[sub r] = 448.10), is triclinic P[bar 1]. The crystal structure has been solved by using 3445 unique reflections to a final R = 0.025 (R[sub w] = 0.030). The main features of this compound lies in its tridimensional network created by connection with hydrogen bonds of associated formula unities arranged in oblique hexagonal prisms. An interatomic bulk of about 2/3 of the unit cell shows an unpacked structure; this agrees with the weakness of all hydrogen bonds in this compound. The IR spectrum of [NH[sub 2]-NH[sub 3]][sub 4]P[sub 4]O[sub 12] is reported and discussed on the basis of a group theoretical analysis. IR data are indicative of the ring character in this compound and also of the local symmetry observed by x-ray diffraction. The correlation between the D[sub 4h] molecular group and the C[sub i] site group leads to the splitting of the OPO- symmetric and POP symmetric and asymmetric stretching mode (E) as a doublet with [Delta][nu] = (15-45) cm[sup [minus]1]. An attempted assignment of frequencies to the stretching and bending modes of the organic group is made according to the previous data.