Issue 21, 2024

Binucleating Jäger-type {(N2O2)2}4− ligands: magnetic and electronic interactions of Fe(ii), Ni(ii) and Cu(ii) across an in-plane TTF-bridge

Abstract

The simultaneous presence of different electrophores provides an interesting playground for responsive materials. Herein, we present the incorporation of a twice-reversibly oxidizable tetrathiafulvalene (TTF) unit into a binucleating ligand, bridging two metal centers in a fully conjugated plane. A two-step synthesis scheme gave the D2h symmetric Schiff base-like ligand H4L in moderate yields from which the corresponding copper(II) [Cu2L], nickel(II) [Ni2L], [Ni2L(py)4] and iron(II) complexes [Fe2L(py)4], [Fe2L(dmap)4] and [Fe2L(bpee)2]·1 Tol could be obtained. Characterization was performed through 1H-NMR, IR, UV-vis and 57Fe-Mössbauer spectroscopy, SQUID magnetometry and cyclic voltammetry, supported by density functional theory (DFT) calculations. Single crystal X-ray analysis of [Ni2L(py)4] revealed six-coordinate paramagnetic centers, whereas [Ni2L] underwent gradual coordination induced spin state switching (CISSS) in solution. The magnetic independence of both metal centers is echoed by close-to-ideal Curie-plots of the [Cu2L] system and the gradual spin crossover of all iron(II) compounds. By contrast, cyclic voltammetry measurements in solution indicated oxidation-dependent TTF–metal interactions, as well as metal–metal interactions. The reversible TTF-borne events in H4L and [Ni2L] are overlaid with metal-borne events in the case of [Fe2L(py)4], as is corroborated by an analysis of the frontier orbital landscapes and through diagnostic spectral features upon chemical oxidation.

Graphical abstract: Binucleating Jäger-type {(N2O2)2}4− ligands: magnetic and electronic interactions of Fe(ii), Ni(ii) and Cu(ii) across an in-plane TTF-bridge

Supplementary files

Article information

Article type
Paper
Submitted
18 Febr. 2024
Accepted
29 Apr. 2024
First published
03 Maijs 2024
This article is Open Access
Creative Commons BY license

Dalton Trans., 2024,53, 9092-9105

Binucleating Jäger-type {(N2O2)2}4− ligands: magnetic and electronic interactions of Fe(II), Ni(II) and Cu(II) across an in-plane TTF-bridge

C. Schreck, S. Schönfeld, P. Liebing, G. Hörner and B. Weber, Dalton Trans., 2024, 53, 9092 DOI: 10.1039/D4DT00479E

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