Revisiting the frontier of the Zintl–Klemm approach for the examples of three Mo2FeB2‐type intermetallics by means of quantumchemical techniques

Abstract

AbstractThe Zintl–Klemm idea is a remarkable formalism that can guide us through the crystal structure–electronic structure relationships of solids showing a particular correlation between charge transfers, (8–N) rule and the corresponding structural fragments. Accordingly, this approach has been applied to interpret the relationships between the crystal and electronic structures for numerous intermetallics; yet, are all of these applications of the Zintl–Klemm idea indeed helpful? To answer this question, quantumchemical means were used to explore the electronic structures of three prototypical intermetallics, i.e. LiY2Si2, Sc2Si2Al, and Y2Pd2In. These compounds crystallize with the Mo2FeB2 type of structure whose structure model may be derived from that of the widely encountered U3Si2‐type. The explorations of the electronic structures included examinations of the Mulliken charges, the projected crystal orbital Hamilton populations (pCOHP), the recently introduced crystal orbital bond indices (COBI) and the respective integrated pCOHP as well as COBI values (IpCOHP and ICOBI). The outcome of these investigations indicates that widely diverse types of bonding are evident for the inspected intermetallics so that the predictive power of the Zintl–Klemm idea is limited.