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Two-Coordinate Co(II) Imido Complexes as Outstanding Single-Molecule Magnets.

Xiao-Nan YaoJing-Zhen DuYi-Quan ZhangXue-Bing LengMu-Wen YangShang-Da JiangZhen-Xing WangZhong-Wen OuyangLiang DengBing-Wu WangSong Gao
Published in: Journal of the American Chemical Society (2016)
The pursuit of single-molecule magnets (SMMs) with better performance urges new molecular design that can endow SMMs larger magnetic anisotropy. Here we report that two-coordinate cobalt imido complexes featuring highly covalent Co═N cores exhibit slow relaxation of magnetization under zero direct-current field with a high effective relaxation barrier up to 413 cm-1, a new record for transition metal based SMMs. Two theoretical models were carried out to investigate the anisotropy of these complexes: single-ion model and Co-N coupling model. The former indicates that the pseudo linear ligand field helps to preserve the first-order orbital momentum, while the latter suggests that the strong ferromagnetic interaction between Co and N makes the [CoN]+ fragment a pseudo single paramagnetic ion, and that the excellent performance of these cobalt imido SMMs is attributed to the inherent large magnetic anisotropy of the [CoN]+ core with |MJ = ± 7/2⟩ ground Kramers doublet.
Keyphrases
  • single molecule
  • transition metal
  • atomic force microscopy
  • living cells
  • room temperature
  • reduced graphene oxide
  • metal organic framework