title: Half-Sandwich Complexes of Dy(III): A Janus-Motif with Facile Tunability of Magnetism.
abstract: Three half-sandwich organometallics [(Cp(R))Dy(DBM)2(THF)]·solvent [Cp(R) = Cp* (1Dy, Cp* = C5Me5), Cp(4PrPh) (2Dy, Cp(4PrPh) = C5Pr4Ph), Cp' (3Dy, Cp' = C5Me4TMS, solvent = THF), DBM(-) = dibenzoylmethanoate anion, THF = tetrahydrofuran, TMS = trimethylsilyl] with a Janus structural motif, where the ligands of DBM(-) and [Cp(R)](-) are widely used in Dy(III)/β-diketonate and Ln(III)/cyclopentadienyl systems, were synthesized, structurally and magnetically characterized, and theoretically investigated. Single-crystal structural analysis reveals that the three complexes crystallize in the same space group P21/c. All the molecules display slow magnetic relaxation in the absence of an applied magnetic field, and the magnetic hysteresis loops of 2Dy and 3Dy can be observed under a magnetic field sweep rate of 10 Oe/s, indicating all three complexes are single-ion magnets (SIMs). The modifications of the Cp-ring lead to the distinct increment of the energy barrier from 46 K (1Dy) to 76 K (2Dy) to 320 K (3Dy). Ab initio calculations show that the ground Kramers doublet is strongly axial with gz approaching the value of 20 expected for the pure MJ = ±15/2 state, and the magnetic anisotropy axes for three complexes share a similar orientation which is perpendicular to the molecular pseudosymmetric axis. Electrostatic analyses confirm the magnetic anisotropy orientations and reveal that proper charge distribution of the coordination sphere (including the first and second) around Dy(III) ion enhances the magnetic anisotropy. Further investigation of the relaxation mechanisms suggests the energy barrier should be carefully used to evaluate single-ion magnets if Raman process is dominant in the low temperature range.
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, No. 5 Yiheyuan Road, Beijing 100871, China.
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Liu
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, No. 5 Yiheyuan Road, Beijing 100871, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Xu
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, No. 5 Yiheyuan Road, Beijing 100871, China.
authors.forename: Shang-Da
authors.initials: SD
authors.lastname: Jiang
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, No. 5 Yiheyuan Road, Beijing 100871, China.
authors.forename: Yi-Quan
authors.initials: YQ
authors.lastname: Zhang
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, No. 5 Yiheyuan Road, Beijing 100871, China.
authors.forename: Yin-Shan
authors.initials: YS
authors.lastname: Meng
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, No. 5 Yiheyuan Road, Beijing 100871, China.
authors.forename: Zitao
authors.initials: Z
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, No. 5 Yiheyuan Road, Beijing 100871, China.
authors.forename: Bing-Wu
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, No. 5 Yiheyuan Road, Beijing 100871, China.
authors.forename: Wen-Xiong
authors.initials: WX
authors.lastname: Zhang
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, No. 5 Yiheyuan Road, Beijing 100871, China.
authors.forename: Zhenfeng
authors.initials: Z
authors.lastname: Xi
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, No. 5 Yiheyuan Road, Beijing 100871, China.
authors.forename: Song
authors.initials: S
authors.lastname: Gao