Pentanuclear {Cr₂Ln₃} (Ln = Dy, Tb) Heterometallic Clusters Based on an Amino Acid Ligand: Slow Relaxation of Magnetization and Substitution Reactions

Abstract

Reactions between Ln3+ (Ln = Dy, Tb), Cr3+, and glycine (HGly) in aqueous solution led to two pentanuclear compounds, Na3[Dy3Cr2(HGly)6(μ3‐OH)6(H2O)9]·(ClO4)8·Cl4·14H2O (1) and Na3[Tb3Cr2(HGly)6(μ3‐OH)6(H2O)9]·(ClO4)6·Cl6·6H2O (2). Structural analyses showed that both 1 and 2 have a {Ln3Cr2} compressed trigonal‐bipyramidal skeleton in which an axial Cr3+ ion lies above and below the triangular equatorial plane defined by the three Ln3+ ions. Magnetic measurements indicated that 1 and 2 exhibit single‐molecule magnetic behavior with Ea ≈ 14.1 K and τ0 = 4.2 × 10–8 s for 1 and Ea ≈ 13.0 K and τ0 = 6.4 × 10–7 s for 2. Interestingly, the clusters are soluble in aqueous solution. The two terminal water molecules of 1 can be substituted by two monocoordinated 4,4′‐dipyridyl N,N′‐dioxide (dpyo) molecules to afford [Dy3Cr2(HGly)6(dpyo)2(μ3‐OH)6(H2O)7]·(ClO4)9·15H2O (3) with a three‐dimensional cds network formed through π–π interactions. Magnetic analysis indicated that 3 also displays slow relaxation of the magnetization with Ea ≈ 13.24 K and τ0 = 9.16 × 10–8 s.

Syntheses, Structures, and Magnetic Properties of a Series of Heterotri-, Tetra- and Pentanuclear LnIII–CoII Compounds

“…The pentanuclear compounds reported in the literature are mostly concentrated in the 3d metal region [ 23 , 24 , 25 , 26 ], and the pentanuclear compounds of 3 d– 4 f heterometallic metals are relatively few [ 27 , 28 , 29 ]. In the reported 3 d– 4 f pentanuclear compounds, the arrangement shapes of pentanuclear metals can be roughly divided into the following types: (a) Trigonal-bipyramidal type [ 30 ], (b) Goblet-like [ 31 ], (c) Butterfly-shaped [ 32 ], (d) Open-book type [ 33 ], (e) T-shaped [ 34 ] and (f) Sandwich-type [ 35 ]. Only one case is similar to the linear structure reported in this paper [ 36 ].…”

Coordination Cluster Nuclearity Decreases with Decreasing Rare Earth Ionic Radius in 1:1 Cr/Ln N-Butyldiethanolamine Compounds: A Journey across the Lanthanide Series from Cr4IIILa4–Cr4IIITb4 via Cr3IIIDy3 and Cr3IIIHo3 to Cr2IIIEr2–Cr2IIILu2

“…In some structures, some or all of the lattice solvent could not be refined satisfactorily and was treated using the SQUEEZE option within the PLATON software. 36 Details of data collection and structure refinement (for fully refined structures) and unit cell data are summarized in Supporting Information , Table S1.…”

A Series Three-Dimensional Ln4Cr4 (Ln = Gd, Tb, Er) Heterometallic Cluster-Based Coordination Polymers Containing Interesting Nanotubes Exhibiting High Magnetic Entropy

“…As far as we know, most of previous works in the field of constructing 3d–4f heterometallic clusters have focused on mixing the later 3d transition metal (TM) (Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ) − ,,− with lanthanide ions, only less efforts have been placed to construct 3d–4f heterometallic clusters by combining early TM ion Cr 3+ with lanthanide ions; this is probably because that Cr 3+ owns an inert nature and strict coordination characteristic. − Nonetheless, due to the isotropic of Cr 3+ and the strong spin orbit coupling of lanthanides, combining Cr 3+ and lanthanides to form 3d–4f clusters with admirable MEC is proved to be a successful approach. , Inspired by the results mentioned above and our previous work, we chose nicotinic acid (HNA) as a rigid ligand to construct a 3D 3d–4f heterometallic clusters-based coordination polymer. This is because, in some cases, HNA can act as a bridge and provide oxygen and nitrogen donors to coordinate with transition metals and lanthanides to participate in the construction of a 3D 3d–4f heterometallic clusters-based framework.…”