On Fe–Fe Dumbbells in the Ideal and Real Structures of FeGa₃

Abstract

The intermetallic phase FeGa3 belongs to the rare examples of substances with transition metals where semiconducting behavior is found. The necessary electron count of 17 ve/fu can be formally derived from eight Fe–Ga and one Fe–Fe two-center–two-electron bond. The situation is reminiscent of the well-known Fe2(CO)9 scenario, where a direct Fe–Fe two-center–two-electron bond was shown to not be present. Fe–Fe interaction in FeGa3 and its substitution variants represents the crucial point for explanation of electronic, thermal transport, and optical properties of this material. Chemical bonding analysis in position space of FeGa3 and Fe2(CO)9 on the basis of the topology of the electron localizability indicator distribution, QTAIM atoms, two- and three-center delocalization indices, domain natural orbitals, IQA analysis, and an evaluation of the Fe–Fe dissociation energy yields a complete picture of the partially compensated Fe–Fe bond, which is nevertheless strong enough to be of decisive importance. Structural reinvestigation of differently synthesized single crystals leads to the composition Fe1+x Ga3 (0 ≤ x ≤ 0.018), where the additional Fe atoms are predicted from DFT/PBE calculations to yield a magnetic moment of about 2 μB/Fe2 atom and metallic in-gap states. Accompanying magnetization and ESR measurements are consistent with this picture.

Polar‐Covalent Bonding Beyond the Zintl Picture in Intermetallic Rare‐Earth Germanides

“…It is now especially interesting to see, that an effective poly coordination of the Ge lone pair type of basins can be even extracted from the ELI‐D distribution alone, without the extra ELI‐D/QTAIM basin intersection technique. In a previous study, it was discussed, that the regions of the negative relative ELI‐D Laplacian , to be abbreviated as in the following, display signatures of bonding interactions on a continuous scale, useful in cases where competing influences prevent the appearance of an ELI‐D attractor, for example, between Fe atoms in Fe 2 (CO) 9 . In the present work, for the first time the ELI‐D fine structure was investigated by analysis of the attractor locations of the negative relative ELI‐D Laplacian distribution.…”

“…In ap revious study, [37] it was discussed, that the regionso ft he negative relative ELI-D Laplacian Àr 2Ỹ s D r ðÞ =Ỹ s D r ðÞ ,t ob ea bbreviated as ÀrL ELID ðÞ in the following, display signatures of bondingi nteractions on ac ontinuous scale, useful in cases where competing influences prevent the appearance of an ELI-D attractor, for example, between Fe atoms in Fe 2 (CO) 9 . [38] In the present work, for the first time the ELI-D fine structure was investigated by analysis of the attractor locations of the negative relative ELI-D Laplacian ÀrL ELID ðÞ distribution. It is to be noted, that the number and location of attractors of ÀrL ELID ðÞ inside an ELI-D basin is not predetermined by the occurrence of the ELI-D basin attractor.E ven if there is only one ÀrL ELID ðÞ attractor,i tn eed not be at exactly the same position as the ELI-Da ttractor.I tc an also happen, that an ELI-D basin does not include a ÀrL ELID ðÞ attractor, for example, in basins not touching any atomicc ore region.…”

Interplay of Atomic Interactions in the Intermetallic Semiconductor Be5Pt

“…[35,36] ELI-D has recently developed into ap owerful quantumchemical tool for the analysis of chemical bonding,p articularly for intermetallic compounds. [20,21,36,37] TheE LI-D distribution reveals three types of bonding interactions in Be 5 Pt, visualised by three different types of attractors (ELI-D maxima; Figures 4b and S3). Tw osets of ELI-D attractors are located at the centres of the tetrahedra formed by Be2.…”

Structural, Magnetic and Thermoelectric Properties of hp‐Mn3Ge5

“…Reducing the number of valence electrons for systems with low charge transfer leads to the occurrence of three‐atomic interactions. Recently this was shown by a detailed analysis of the bonding in the thermoelectric material, Fe 1+ x Ga 3 . Here, an appropriate redistribution of the available valence electrons between the two‐ and three‐atomic interactions is realized and a saturated bonding picture is achieved (electron deficiency supports also the participation of the d electrons in the bonding interactions).…”