Front Cover: A Tetrapodal Penta‐Carbene Ligand and Iron(III) Complex (Eur. J. Inorg. Chem. 20/2023)

Abstract

The Front Cover shows selected tetrapodal‐pentadentate “butterflies” taking flight. First noted as bearing resemblance to butterflies by Paine and Nordlander, these 5‐coordinate frameworks have found applications in areas such as H2 evolution catalysis, N2 reduction chemistry, and as scaffolds to support high‐valent metal‐oxo compounds. Our contribution to this topology consists of a carbon butterfly composed of five N‐heterocyclic carbene donors bridged by arylborate linkers to provide a dianionic framework upon removal of five protons. More information can be found in the Research Article by J. J. Scepaniak and co‐workers.

A S=3/2 Cr(III) Complex In A Square‐Capping NHC Framework

“…FeCl. [28] While the elongation of the C (ax) -M bond (Cr1-C1 2.029(2) Å vs. Fe1-C1 1.944(3) Å) can be anticipated to lower the trans influence of the axial NHC donor, the subtle geometric change is likely too little to improve orbital overlap between Cr and an incoming σ-donor like the PhC 2…”

“…NHC ligands are an attractive alternative to widely used phosphine ligands as they share strong σ-donor and moderate π-accepting ability, are insensitive to oxidizing conditions, [26] and can support a wide variety of oxidation states best exemplified by isolable complexes of iron ranging from + 6 to 0. [13,19,27] In an extension of our previous work describing the preparation of a square-capping NHC framework and coordination chemistry of an Fe III complex [28] we report herein the preparation and characterization of a Cr III complex as an entrypoint to the study of the coordination chemistry of Cr in this strongly donating framework. Besides finding metallurgical applications, Cr is used in industrial scale chemical transformations including the Philips chromium catalyst and chromium oxide-based dehydrogenation catalyst.…”