Divergent Coordination Chemistry: Parallel Synthesis of [2×2] Iron(II) Grid‐Complex Tauto‐Conformers

Abstract

The coordination of iron(II) ions by a homoditopic ligand L with two tridentate chelates leads to the tautomerism‐driven emergence of complexity, with isomeric tetramers and trimers as the coordination products. The structures of the two dominant [FeII 4 L 4]8+ complexes were determined by X‐ray diffraction, and the distinctness of the products was confirmed by ion‐mobility mass spectrometry. Moreover, these two isomers display contrasting magnetic properties (FeII spin crossover vs. a blocked FeII high‐spin state). These results demonstrate how the coordination of a metal ion to a ligand that can undergo tautomerization can increase, at a higher hierarchical level, complexity, here expressed by the formation of isomeric molecular assemblies with distinct physical properties. Such results are of importance for improving our understanding of the emergence of complexity in chemistry and biology.

Molecular Spin Crossover Materials: Review of the Lattice Dynamical Properties

“…This isotope sensitivity implies certain limitations, but can also provide advantages. Notably, in the case of iron‐based SCO complexes, this feature was used at several instances to analyze vibrational modes of the coordination octahedron . As an example, Figure shows the partial VDOS of the SCO complex [Fe(HB(tz) 3 ) 2 ] in the two spin states extracted from NIS experiments .…”

Exploring the light-induced dynamics in solvated metallogrid complexes with femtosecond pulses across the electromagnetic spectrum

“…The prospect of overcoming these hurdles is currently spurring a significant synthetic effort toward oligonuclear complexes, since they often interconvert between stable and adaptable conformers that respond to the changes in the surroundings (Bodenthin et al, 2009;Halder, 2002;and Wang et al, 2013). For example, homometallic, heterometallic, and mixed valence [2 × 2] grid complexes, which are actively pursued for high-density data storage and miniaturization in the field of molecular electronics, have recently emerged as self-assembling nanosized platforms that can sustain multiple spin-switching (Schäfer et al, 2016;Matsumoto et al, 2014;Schneider et al, 2013;Schneider et al, 2010;Wu et al, 2009;and Nihei et al, 2005), charge transfer (Ohkoshi et al, 2011;Liu et al, 2010;, and redox modulation (Shen et al, 2015;Wang et al, 2013;Schneider et al, 2010;Ruben et al, 2004;. The optimization of these properties could ultimately produce photosensitizers, reactive centers, or catalysts achieving superior operando performances.…”

Expanding the Family of Pyrazole‐Bridged Mixed‐Spin and Mixed‐Valence Tetranuclear [2 × 2] Iron Grid Complexes

“…Alternatively, different and interconvertible electronic or magnetic configurations may exist for mixed‐valent Fe II 2 Fe III 2 grids. However, so far relatively few Fe 4 grid complexes are known to display these phenomena …”