title: Two-Coordinate Co(II) Imido Complexes as Outstanding Single-Molecule Magnets.
abstract: 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.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, PR China.
authors.forename: Xiao-Nan
authors.initials: XN
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, PR China.
authors.forename: Jing-Zhen
authors.initials: JZ
authors.lastname: Du
authors.affiliation: Jiangsu Key Laboratory for NSLSCS, School of Physical Science and Technology, Nanjing Normal University , Nanjing 210023, PR China.
authors.forename: Yi-Quan
authors.initials: YQ
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, PR China.
authors.forename: Xue-Bing
authors.initials: XB
authors.lastname: Leng
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, PR China.
authors.forename: Mu-Wen
authors.initials: MW
authors.lastname: Yang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, PR China.
authors.forename: Shang-Da
authors.identifier: 0000-0003-0204-9601
authors.initials: SD
authors.lastname: Jiang
authors.affiliation: Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology , Wuhan 430074, PR China.
authors.forename: Zhen-Xing
authors.initials: ZX
authors.lastname: Wang
authors.affiliation: Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology , Wuhan 430074, PR China.
authors.forename: Zhong-Wen
authors.initials: ZW
authors.lastname: Ouyang
authors.affiliation: State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, PR China.
authors.forename: Liang
authors.initials: L
authors.lastname: Deng
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, PR China.
authors.forename: Bing-Wu
authors.identifier: 0000-0001-8092-5959
authors.initials: BW
authors.lastname: Wang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, PR China.
authors.forename: Song
authors.initials: S
authors.lastname: Gao