MgMn₄Ga₁₈: a novel three-shell gallium cluster structure

Abstract

The new ternary gallide MgMn4Ga18 (magnesium tetramanganese octadecagallium) was synthesized and its crystal structure determined by means of single-crystal X-ray diffraction. The MgMn4Ga18 structure can be described as that of a three core–shell cluster compound. The Mg atoms are surrounded by 16 adjacent Ga atoms, [MgGa16], and the respective coordination polyhedron is an octadecahedron. This [MgGa16] octadecahedron is encapsulated inside a [Ga32] icohexahedron, which is in turn encapsulated inside a [Ga40] pentacontaoctahedron. As a result, a three core–shell cluster, [MgGa16@Ga32@Ga40], is identified. Electronic structure calculations were performed by means of the TB-LMTO-ASA program and additionally confirm the existence of the core–shell packing of the clusters.

Crystal, electronic structure and hydrogenation properties of the Mg5.57Ni16Ge7.43 cluster phase with a new type of polyhedron

“…6). Earlier, we described the structure of the cluster phase MgMn 4 Ga 18 (Pavlyuk et al, 2022b), for which we discovered a pentacontaoctahedron with V = 40, F = 58 and E = 96, and also a convex polyhedron (� = 2). We also described previously the formation of clusters in magnesiumcontaining intermetallics using the example of the quaternary phase Li 20 Mg 6 Cu 13 Al 42 with a 60-atom truncated icosahedron (Pavlyuk et al, 2019) and new cubic cluster phases in the Mg-Ni-Ga system (Pavlyuk et al, 2020).…”

Na2Ga7: A Zintl–Wade Phase Related to “α-Tetragonal Boron”

“…Intermetallic compounds with high gallium content form a variety of complex crystal structures reflecting the difficulty of achieving a closed-shell configuration with three valence electrons. − Within group 13 of the periodic table, gallium allotropes are structurally unique. Gallium transforms to an fcc packing like aluminum only at extreme conditions, , and it has a much lower tendency than boron to form icosahedra, which have only been observed in δ-Ga .…”