Dr. Svilen Bobev
University of Delaware
Department of Chemistry and Biochemistry
Friday, February 24, 2023
Room 120 – Meyerhoff Chemistry Building
Host: Dr. Joe Bennett
“Novel Zintl phases based on group 15 elements with and late d-metals”
Zintl phases are compounds of the alkali or alkaline-earth metals and the early post-transition elements. The electropositive metals are the “cations” and they donate their valence electrons to the electronegative elements from groups 13, 14 and 15, which in turn, form covalent bonds to form the anionic building blocks of the structure. The electron transfer is typically considered to be “complete”, and all constituent atoms should attain closed-shell configurations. Many known solid-state compounds in the ternary A–M–Pn systems (A = alkali or alkaline-earth metals, M = Cu, Zn, Cd, Pn = pnictogen, i.e., group 15 elements) can be classified as Zintl phases.
As part of an ongoing effort to better understand the structure-property relationships in intermetallic compounds containing metals/semimetals with different electronegativities, we focused our attention on the structures, and physical properties on antimonides and bismuthides. Recent experimental work carried out by our group led to the discovery of several new classes of d-metal based compounds. Common features in the structures of all of these are the M-centered tetrahedra of Sb or Bi, MSb4 and MBi4, respectively, which are interconnected through shared corners or edges to form chains, ribbons, or layers with complex topologies. These systems present a case where a strikingly delicate balance between the packing efficiency (size effects) and the valence electron concentration (electronic effects) governs the stability of a particular arrangement over another. The structural relationship between these and other structures with two-dimensional layers or three-dimensional four-connected nets will be discussed as well.