Be₃Ru: Polar Multiatomic Bonding in the Closest Packing of Atoms

Abstract

The new phase Be 3 Ru crystallizes with TiCu 3 -type structure (space group Pmmn (59), a = 3.7062(1) Å, b = 4.5353(1) Å, c = 4.4170(1) Å), a coloring variant of the hexagonal closest packing (hcp) of spheres. The electronic structure revealed that Be 3 Ru has a pseudo-gap close to the Fermi level. A strong charge transfer from Be to Ru was observed from the analysis of electron density within the Quantum Theory of Atoms in Molecules (QTAIM) framework and polar three-and four-atomic BeÀ Ru bonds were observed from the ELIÀ D (electron localizability indicator) analysis. This situation is very similar to the recently investigated Be 5 Pt and Be 21 Pt 5 compounds. The unusual crystal chemical feature of Be 3 Ru is that different charged species belong to the same closest packing, contrary to typical inorganic compounds, where the cationic components are located in the voids of the closest packing formed by anions. Be 3 Ru is a diamagnet displaying metallic electrical resistivity.

Structural Complexity in the Apparently Simple Crystal Structure of Be2Ru

“…Thus, the multiatomic Ru−Be bonds in Be 2 Ru (Fe 2 P type) are essentially polar. This finding is completely in line with the bonding analysis of the chemically homologous compound Be 3 Ru, where multi‐atomic Be−Ru interactions are found to stabilize the crystal structure [14] . Similar features of the bond basins were evaluated for the NbRuB‐type model of Be 2 Ru (Figure S8, Supporting Information).…”

“…They are far from spherical form. The shapes of Be species in both models are convex and compact, being similar to that found for Be in Be 3 Ru, [14] Be 21 Pt 5 [15] or Be 5 Pt. [16] The QTAIM Ru atoms have concave surfaces toward neighbouring beryllium species and flatter ones toward homoatomic neighbours indicating the appearance of rather different atomic interactions, like it was found in chemically homologous Mg 29 Pt 4 [17] and Mg 3 GaIr.…”

“…Two endothermic signals at 1520 °C and at 1540 °C are detected in the DSC heating curve of Be 2 Ru, and they find their equivalents in the cooling curve (Figure S2 in the Supporting Information). Such thermal behaviour is assigned for a peritectic formation of the main phase at 1520 °C from the Be‐rich phase Be 3 Ru, [14] and crossing of the liquidus at 1540 °C.…”

Flux Growth, Crystal Structure, and Chemical Bonding of Yb2PdGe3, an AlB2Superstructure within the Rare-Earth Series

“…Interestingly, these characteristic features of covalently bonded p -block elements are practically identical for both germanium and palladium. Such intriguing anionic behavior of palladium and other transition metals (e.g., Ru, Ir, Pt, Au, Ag) has been increasingly reported in the literature ,,− and considered responsible for unprecedented chemical properties. , Hence, the QTAIM effective charges indicate that the crystal structure of Yb 2 PdGe 3 is composed of false[ PdGe 3 false] ∞ 2 honeycomb anionic layers spaced by Yb cations.…”

Magnetic phase separation in the EuPdSn2ground state

“…Interestingly, Eu is the only QTAIM cation (+1.02) and Pd bears a negative effective charge of À0.92, enriching the family of intermetallic compounds containing an anionic late transition metal. [44][45][46][47][48][49][50] The Q eff (Eu) is almost half of the formal one supporting its involvement in covalent interactions. The shapes of the atomic basins are quite characteristic for transition metal rare-earth tetrelides: Eu cations are quite spherical whereas both Pd and Sn display polyhedral shapes, sharing convex surfaces with Eu and flat among them.…”