Polar Intermetallics Pr₅Co₂Ge₃ and Pr₇Co₂Ge₄ with Planar Hydrocarbon‐Like Metal Clusters

Abstract

Planar hydrocarbon-like metal clusters may foster new insights linking organic molecules with conjugated π-π bonding interactions and inorganic structures in terms of their bonding characteristics. However, such clusters are uncommon in polar intermetallics. Herein, we report two polar intermetallic phases, Pr Co Ge and Pr Co Ge , both of which feature such planar metal clusters, namely, ethylene-like [Co Ge ] clusters plus the concatenated forms and polyacene-like [Co Ge ] ribbons in Pr Co Ge , and 1,2,4,5-tetramethylbenzene-like [Co Ge ] cluster in Pr Co Ge . Just as in the related planar organic structures, these metal-metalloid species are dominated by covalent bonding interactions. Both compounds magnetically order at low temperature with net ferromagnetic components: Pr Co Ge through a series of transitions below 150 K and Pr Co Ge through a single ferromagnetic transition at 19 K. Spin-polarized electronic structure calculations for Pr Co Ge reveal strong spin-orbit coupling within Pr and considerable magnetic contributions from Co atoms. This work suggests that similar structural chemistry can emerge for other rare-earth/late-transition-metal/main-group systems.

Exceedingly small moment itinerant ferromagnetism of single crystalline La5Co2Ge3

“…Single crystals of La 5 Co 2 Ge 3 were grown using a self-flux solution growth method [9][10][11]. The initial composition of the three elements was La:Co:Ge = 45:45:10.…”

Anionic cobalt-platinum-ethynyl (CoPt–C2H) metal-organic subnanoparticles: a DFT modeling study

“…The reactions of hydrocarbons on transition metals are among the most important industrial catalytic processes [21][22][23][24][25][26]. The interaction of transition metals with unsaturated hydrocarbons has, therefore, received significant attention [21,22,[27][28][29][30].…”

“…The interaction of transition metals with unsaturated hydrocarbons has, therefore, received significant attention [21,22,[27][28][29][30]. Adsorption of a small molecule or atom may modify the electronic and magnetic properties and stability of transition metal clusters.…”

Electron-Poor Polar Intermetallics: Complex Structures, Novel Clusters, and Intriguing Bonding with Pronounced Electron Delocalization

“…Unfortunately, it is difficult to assign unambiguous formal charges to these metal-metalloid clusters arising from the unknown formal charge of Co and incomplete charge transfer from Pr to Co/Ge. As yet, the evidence is insufficient to conclude whether the Hückel (4n + 2)π-electron counting rule applies for aromaticity or not.But, electron delocalization within the planar Co-Ge clusters is evident from charge density and electron localization function (ELF) plots,55 as well as COHP plots for Co−Co and Co−Ge interactions, shown in Figure 12, which identify the states near the Fermi level to be Co−Co and Co−Ge antibonding. Onn the other hand, Pr−Co and Pr−Ge COHP curves indicate weakly bonding states at the Fermi level, which together with the Co−Co and Co−Ge COHP results suggest a delocalized bonding picture for the planar hexagonal Co-Ge cluster capped by Pr.…”

“…5 Co 2 Ge 355 features two unprecedented molecular species, Co 2 Ge 4 and (Co 2 Ge 2 ) n with geometries resembling ethylene and polyacene, respectively. These two moieties interpenetrate planar honeycomb nets of rare earth atoms to form slabs that alternately stack with layers of rare earth tetrahedra.…”