Alkali-regulated and molecular clusters and their structural transformation

As a kind of metastable aggregation between iron ions and iron hydroxide precipitates, Fe clusters can only be isolated under narrow synthesis conditions. Here, two Fe clusters with different structural models, [Fe-6(H(2)thmmg)(6)] (Fe-6) and [Fe18O8(OH)(8)(H(2)thmmg)(10)] (Fe-18), are constructed based on a rare N-tris(hydroxymethyl)methylglycine (H(5)thmmg) ligand. The cyclic Fe-6 can be visualized as a six-vane windmill comprised of 6 Fe3+ and 6 H(2)thmmg(3-) ligands. Unlike the cyclic configuration of Fe-6, the Fe-18 cluster features a bricky structure like a Chinese knot coordinated by three species, H(2)thmmg(3-), OH- and O2-. It was obtained by adding more triethylamine to the reactive solution of Fe-6 which yielded more coordinated species OH- and O2-. Moreover, the conversion from Fe-6 to Fe-18 was successfully achieved by adding more triethylamine, realizing nuclearity enlargement and structural regulation of Fe clusters. Furthermore, the magnetic properties of Fe-6 and Fe-18 exhibit antiferromagnetism. This work reports two novel alkali-regulated Fe clusters and further realizes the transformation of nuclearity and structure, which provides some reference for the structural predesign and adjustment of metal nanoclusters.

Automated summary

This study constructed two novel Fe clusters, Fe-6 and Fe-18, with different structural models based on a rare H(5)thmmg ligand. The transition from Fe-6 to Fe-18 was successfully achieved by adding more triethylamine, leading to nuclearity enlargement and structural regulation. Additionally, both Fe-6 and Fe-18 clusters exhibit antiferromagnetism, providing insights for the structural predesign and adjustment of metal nanoclusters.