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Controlling the Regioselectivity of Topochemical Reduction Reactions Through Sequential Anion Insertion and
Romain Wernert1, Bodoo Batnaran1, Michael A Hayward1
1Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK.
Angewandte Chemie (International Ed. in English)
|September 10, 2025
Summary
Researchers modified topochemical reduction reactions by introducing a fluorinate-then-reduce strategy. This approach enables the synthesis of novel reduced phases with tunable dimensionality and magnetic properties.
Area of Science:
- Solid-state chemistry
- Materials science
- Inorganic chemistry
Background:
- Ruddlesden-Popper oxides are a class of materials with layered structures.
- Topochemical reduction is a method to modify oxide structures by removing oxygen.
- Controlling the dimensionality of transition metal arrangements is key for tuning material properties.
Purpose of the Study:
- To investigate the effect of a fluorinate-then-reduce strategy on topochemical reduction of Ruddlesden-Popper oxides.
- To synthesize and characterize new reduced oxyfluoride phases.
- To explore the relationship between crystal structure dimensionality and magnetic properties.
Main Methods:
- Topochemical reduction of LaSr2CoRuO7 to LaSr2CoRuO5.3.
- Fluorination of LaSr2CoRuO7 to LaSr2CoRuO5.5F3.5.
- Subsequent reduction of the oxyfluoride to LaSr2CoRuO4.5F1.5.
- Structural characterization using X-ray diffraction.
- Magnetic property measurements.
Main Results:
- The fluorinate-then-reduce strategy successfully yielded LaSr2CoRuO4.5F1.5, an oxyfluoride with a 2D infinite sheet structure of (Co/Ru)O4 squares.
- This contrasts with the 1D infinite double-chain structure obtained by direct reduction of LaSr2CoRuO7.
- Both LaSr2CoRuO5.3 and LaSr2CoRuO4.5F1.5 exhibit glassy magnetic states, with stronger interactions in the 1D phase.
- The fluorinated intermediate LaSr2CoRuO5.5F3.5 directs the regioselectivity of the reduction.
Conclusions:
- The fluorinate-then-reduce strategy offers a versatile route to control the dimensionality of transition metal connectivity in reduced phases.
- This method allows access to novel "infinite-layer" reduced compounds not achievable through direct reduction.
- The dimensionality of transition metal networks significantly influences magnetic interactions in these materials.
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