Modulated crystal structure of InMo₄O₆

Abstract

The (3 + 1)-dimensional modulated crystal structure of the metal-rich cluster compound InMo4O6 was solved and refined from single-crystal data in the superspace group P4/mbm(00γ)00ss [q = 0, 0, 0.1536 (4); a = 9.6664 (9), c = 2.8645 (3) Å; R1(all) = 0.046, wR(all) = 0.076]. The crystal structure is closely related to the NaMo4O6 structure type. It is built from rods of Mo6 clusters condensed via trans edges. These form channels parallel to [001], in which In6 and In7 oligomers alternate. Weak diffuse planes parallel to (001)* interconnect the satellite reflections; they occur due to two-dimensional rod disorder of the In oligomer chains.

LiMo8O10: Polar Crystal Structure with Infinite Edge-Sharing Molybdenum Octahedra

“…The parallel edge-sharing Mo 6 octahedra chain extends along the a axis in one layer and then rotates 90° (along the b axis) in the adjacent layer in a crosswise layout connected by the shared O4 and O5 atoms. The special layout of the Mo 6 octahedra chain in the crystal structure of LiMo 8 O 10 is different from the parallel feature of the Mo 6 octahedra chain in AMo 4 O 6 (A = Na, K, In, and Sn), − Sc 0.75 Zn 1.25 Mo 4 O 7 , R 4 Mo 4 O 11 , and Mn 1.5 Mo 8 O 11 . , The Mo 6 octahedra are coordinated with twelve O atoms above corners and free edges and form a “Mo 6 O 12 ” cluster (Figure f). Considering the shared O and Mo atoms together, the connective formula is Mo 2 Mo 4/2 O 6/2 O 6/3 (leading to a “Mo 4 O 5 ” unit).…”

“…This pairwise distortion between apical Mo atoms is also observed in isostructural ZnMo 8 O 10 , related R 4 Mo 4 O 11 , Mn 1.5 Mo 8 O 11 , and Sc 0.75 Zn 1.25 Mo 4 O 7 compounds featuring infinite chains of edge-sharing Mo 6 octahedra. One exception is the AMo 4 O 6 (A = Na, K, In, and Sn; space group P 4/ mbm ) crystal structure, − which contains undistorted chains of Mo 4 O 6 units.…”

“…Solid-State 7 Li and 6 Li NMR. To confirm the existence of Li elements and study the local coordination environment of Li atoms in the crystal structure, solid-state 7 Li and 6 Li NMR were conducted using LiCl and Li 2 O as the reference compounds. Both 7 Li and 6 Li MAS NMR spectra collected at room temperature show obvious peaks at 13.00 and 12.99 ppm, respectively (Figure 5).…”

“…27 The 6 Li chemical shift of LiMo 8 O 10 indicates the tetrahedral environment of Li atoms, as shown in the crystal structure Figure 1b. To check the Li mobility, we also collected 7 Li MAS NMR spectra at 238 K. In comparison to the main resonance at 13.00 ppm obtained at 298 K, a sharper peak occurs at 12.70 ppm at 238 K. The main resonance shift indicates the change of distribution under a similar coordination environment. The broadening effect of resonances at a higher temperature suggests wider distribution due to higher mobility.…”

“…They have infinite chains of Mo 4 O y cluster units containing condensed edge-sharing Mo 6 octahedra with Mo–Mo metal bonding. Reported examples include AMo 4 O 6 (A = Na, K, In, and Sn; space group P 4/ mbm ), − Sc 0.75 Zn 1.25 Mo 4 O 7 (space group Imam ), isostructural Ti 0.5 Zn 1.5 Mo 4 O 7 , GaMgMo 4 O 7 , Fe 2 Mo 4 O 7 , AMo 8 O 10 (A = Li, Zn; space group I 4 1 md ), R 4 Mo 4 O 11 (R = Y, Nd, and Sm-Tm; space group Pbam ), and Mn 1.5 Mo 8 O 11 (space group P 2 1 / a and P 2 1 / n ). , The metallic behavior in AMo 4 O 6 (A = Na and In) and Mn 1.5 Mo 8 O 11 ,, and the metal-to-insulator transition in AMo 4 O 6 (A = K and Sn), ,, have been attributed to the infinite Mo–Mo bonding chains in the crystal structure. Among these reported compounds, AMo 4 O 6 (A = Na and K) and LiMo 8 O 10 belong to ternary alkali metal molybdenum oxides, and LiMo 8 O 10 is the only one that adopts a polar space group.…”