Intermetallic Chemistry - American Chemical Society

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Editorial pubs.acs.org/accounts

Cite This: Acc. Chem. Res. 2018, 51, 213−213

Intermetallic Chemistry: New Advances in Humanity’s Age-Old Exploration of Metals and Alloys Guest Editorial for the Accounts of Chemical Research special issue on “Advancing Chemistry through Intermetallic Compounds”.

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the search for trends, the identification of key parameters, and the development of models to predict new materials. Another striking feature in these Accounts is the use of chemical insight in the search for new compounds and to optimize their properties. The notion that transition metals have greater flexibility in their coordination environments than Si or Ge leads to unprecedented clathrate-related materials, whereas incorporating them into fluxes to synthesize antimonides can lead to low-dimensional materials. Complex doping regimens are designed to engineer the thermoelectric properties, while the electronic structure and geometrical arrangements of intermetallic surfaces are correlated with catalytic properties. Overall, one of the greatest contributions of this issue is its illustration of the strong interplay between intermetallic compounds and molecular chemistry. Molecular concepts of bonding and structure continually inform the design of experiments and calculations, as well as the interpretation of their results. At the same time, many of the intermetallic systems explored in this issue yield opportunities to broaden these molecular concepts, offer new reactivity through their catalytic properties, and reveal the behavior of the elements of the periodic table in an expanded range of contexts. It will be exciting to see what avenues the millennia-old exploration of the metallic state will next open for science and civilization.

he preparation of new metallic materials is an endeavor that stretches back to antiquity and is closely tied to the progress of civilization and the development of chemistry as a science. And yet, it was only during the early 20th century that their richness as chemical systems began to be fully appreciated, with X-ray diffraction experiments revealing a staggering diversity of intermetallic crystal structures. As might be expected from structure−function relationships elsewhere in chemistry, this breadth of atomic arrangements underlies a wealth of chemical and physical properties, including catalysis, superconductivity, magnetic phenomena, thermoelectric effects, and shape memory. These outcomes, however, only hint at the full potential of intermetallic phases for advancing chemistry and applications in society. Synthetic exploration continues to reveal new compounds, the properties of the majority of known intermetallic compounds have not been characterized, and establishing relationships among bonding, structure, and behavior remain open challenges for most classes of these phases. This special issue of Accounts of Chemical Research celebrates the substantial and expanding role that intermetallic phases play within the broader context of chemistry. Throughout this collection, the discovery, elucidation, and application of intermetallic phases will be repeatedly seen to be a chemical endeavor, with far reaching implications for the field. A nearly universal theme is the boundless diversity of intermetallic structures and properties, which continue to develop through advances in experimental capabilities, such as new synthetic approaches and in situ experiments using synchrotron radiation. Structural intergrowths, incommensurate modulations, phase transitions, and a plethora of new bonding phenomena will all be encountered in these pages. Also evident in these Accounts is the pressing desire for concepts that make sense of intermetallic compounds and offer predictions for their structures and properties. The growing catalog of structural and thermodynamic data has outgrown the confines of printed volumes leading to massive online databases. As a result, a wide range of approaches needed to wrestle the collected observations on intermetallic compounds is taken. Bonding analysis is used to find commonalities and progressions within intermetallic structures, often placing different compounds along a continuum between structures governed by the octet rule and localized two-center, twoelectron bonds at one extreme (the simplest Zintl compounds) and perturbations on the free electron gas (Hume-Rothery phases) at the other, with exceptional multicenter bonding arising in the middle ground. Recognizing recurring structural themes in the solid state is also prevalent and thoughtprovoking, even prompting proposals about the existence of clusters in the melt. Finally, by acknowledging the limitations and subjectivity of the human mind, computers are enlisted in © 2018 American Chemical Society

Daniel C. Fredrickson, Guest Editor University of WisconsinMadison

Gordon J. Miller, Guest Editor

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Iowa State University

AUTHOR INFORMATION

ORCID

Daniel C. Fredrickson: 0000-0002-3717-7008 Gordon J. Miller: 0000-0001-5717-8000 Notes

Views expressed in this editorial are those of the authors and not necessarily the views of the ACS.

Published: February 20, 2018 213

DOI: 10.1021/acs.accounts.8b00035 Acc. Chem. Res. 2018, 51, 213−213