Synthesis, Structure and Vibrational Spectra of Ba₁₄InP₁₁

Ba 14 InP 11 was prepared from the elements in a sealed stainless steel ampoule at 1345 K. The compound is black, brittle and very sensitive to air and moisture. Ba 14 InP 11 crystallises in the tetragonal Ca 14 AlSb 11 type (space group I 4 1 / acd , No. 142; a = 17.097 (2) Å, c , = 8, Pearson code tI 208). The structure contains isolated P 3‐ , linear [P 3 ] 7‐ and tetrahedral [InP 4 ] 9‐ anions. The X‐ray structure analysis and the vibrational spectra show that the [P 3 ] 7‐ polyanion is strongly asymmetric with d (P–P) = 2.28 Å and 4.10 Å, corresponding to a [P 2 ] 4‐ dumbbell weakly coupled to a single p 3‐ anion. The tetraphosphidoindate(III) anion [InP 4 ] 9‐ is slightly compressed along the 4 axis, with bond lenght d (In–P) = 2.71 Å. It is shown that the structure is hierarchically related to that of Cu 2 O, with two interpenetrating frameworks, in which the O and Cu atoms are replaced by condensed [InP 4/2 ] tetrahedron and [BaP 4 P 2/2 ] octahedra, respectively. Both frameworks are meso configured, containing alternate R and S fragments. The other Ba cations envelop the P 6 octahedra and P 3 triads forming condensed cubes, tetragonal antiprisms and bicapped trigonal prisms. Therefore, the structure also forms a heterogeneous framework of centred PBa 8/2 tap tetragonal antiprisms and BaBa 8/2 cub cubes, consisting of two interpenetrating enantiomorphic nets ( R and S ) similar to those in the cubic phase RhBi 4 .