European Journal of Inorganic Chemistry
European Journal of Inorganic Chemistry
4 years ago

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

Expanding the Family of Pyrazole-Bridged Mixed-Spin and Mixed-Valence Tetranuclear [2 × 2] Iron Grid Complexes
Jin Tong, Serhiy Demeshko, Franc Meyer, Sebastian Dechert
The new bis(tridentate) compartmental proligand 3,5-bis[6-(1-methyl-1H-imidazole-2-yl)pyrid-2-yl]pyrazole (HLim) was synthesized and used for the self-assembly of a rugged tetranuclear [2 × 2] Fe4 grid complex [FeII4Lim4](ClO4)4 (1), which readily forms upon reaction of HLim with Fe(ClO4)2·6H2O in the presence of a base (NaOtBu). According to cyclic voltammetry, all-ferrous 1 can be sequentially oxidized in four steps, with pronounced stability of the twice-oxidized dimixed-valent form [FeII2FeIII2Lim4]6+. Treatment of 1 with the oxidant AgClO4 yielded the dimixed-valent molecular grid [FeII2FeIII2Lim4](ClO4)6 (2) and an unusual heterometallic grid [FeIII2(AgI2)2Lim4](ClO4)6. (3), depending on reaction conditions. 3 can also be synthesized via the intermediate “corner complex“ [FeII(HLim)2](ClO4)2. Complexes 1, 2 and 3 were characterized by single-crystal X-ray diffraction analysis as well as by SQUID magnetometry and Mössbauer spectroscopy. 1 is shown to adopt a dimixed-spin trans-[HS-LS-HS-LS] configuration (HS: high-spin; LS: low-spin) while 2 features ferromagnetic coupling in a trans-[FeIII(LS)-FeII(HS)-FeIII(LS)-FeII(HS)] configuration. Correlations between structural parameters and magnetic properties are analyzed and discussed in comparison with previously reported Fe4 grids based on related pyrazole-bridged ligands. A new pyrazole-based bis(tridentate) ligand has been synthesized and used for the self-assembly of an all-ferrous Fe4 [2 × 2] grid complex, which can be oxidized twice to its dimixed-valent congener. Trans dimixed-spin configurations for both grids were established by a combination of crystallographic, magnetic and Mössbauer studies.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/ejic.201700733

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.