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

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• 作者：Xiao-Nan Yao ; Jing-Zhen Du ; Yi-Quan Zhang ; Xue-Bing Leng ; Mu-Wen Yang ; Shang-Da JiangZhen-Xing Wang ; Zhong-Wen Ouyang ; Liang Deng ; Bing-Wu Wang ; Song Gao
• 刊名：Journal of the American Chemical Society
• 出版年：2017
• 出版时间：January 11, 2017
• 年：2017
• 卷：139
• 期：1
• 页码：373-380
• 全文大小：485K
• ISSN：1520-5126

文摘

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 |M_J = ± 7/2⟩ ground Kramers doublet.