Rare single-molecule magnets with six-coordinate Ln^IIIions exhibiting a trigonal antiprism configuration

Abstract

Four Ni-Ln-Ni heterometallic complexes, [Ni2LnL2]NO3·3H2O (H3L = tri(((3-methoxysalicylidene)amino)ethyl)amine, Ln = Gd for , Tb for and Dy for , respectively) and [Ni2DyL2]ClO4·MTBE·0.65H2O (, MTBE = methyl tert-butyl ether) have been synthesized by diffusion of methyl tert-butyl ether vapor into the reaction solution. The X-ray analyses demonstrated that the Gd(III) ion in exhibits rare seven-coordination, the Tb(III) and Dy(III) ions in display unusual six-coordination, and two Ni(II) ions and one Ln(III) ion are bridged by six phenolato atoms to form linear Ni-Ln-Ni heterotrinuclear complexes for . All complexes exhibit weak ferromagnetic interactions between Ni(II) and Ln(III) ions. Alternating current susceptibility measurements demonstrated that compounds and behave as single-molecule magnets with the effective energy barriers of 14.17 and 11.13 K under zero direct current field. They are rare single-molecule magnets containing six-coordinate Dy(III) ions.

Trinuclear NiII-LnIII-NiII Complexes with Schiff Base Ligands: Synthesis, Structure, and Magnetic Properties

“…Complexes [(NiL 1 ) 2 Ln](ClO 4 ) (H 3 L 1 = (S)P[N(Me)N=CH-C 6 H 3 -2-OH-3-OMe] 3 , Ln III = La-Er, except Pm) [11,12], [(NiL 2 ) 2 Gd](NO 3 ) (H 3 L 2 = 6,6 -((1E)-((2-(((E)-(2-hydroxy-3-methoxybenzylidene)amino)methyl)-2-methylpropane-1,3-diyl)bis(azanylylidene))bis(methanyl ylidene))bis(2-methoxyphenol) [13], [(NiL 3 ) 2 Ln](NO 3 ) (Ln III = Gd, Tb, Dy) and [(NiL 3 ) 2 Dy](ClO 4 ) (H 3 L 3 = 6,6 ,6"-((1E,1 E)((nitrilotris(ethane-2,1-diyl))tris(azanylylidene))tris(methanylylidene))tris(2methoxyphenol) [14], [(NiL 4 ) 2 Ln(H 2 O) 1/0 ](ClO 4 ) (H 3 L 4 = 6,6 ,6"-((1,4,7-triazonane-1,4,7-triyl)tris(methyl ene))tris(2-methoxy-3-methylphenol), Ln III = Y, La, Ce-Lu, except Pr, Pm, Yb) [15], [(NiL 5 )Tb](ClO 4 ) (H 3 L 5 = 6,6 ,6"-((1,4,7-triazonane-1,4,7-triyl)tris(methylene)) tris (2,3-dimethylphenol) [16], [(NiL 6…”

“…3 ) 2 Ln](NO 3 ) (HL 6 = (Z)-2-methoxy-6-((phenylimino)methyl)phenol, Ln III = La, Pr, Gd, Tb) [17,18], and [{Ni{L 7 ) 1.5 } 2 Ln(OH)] (H 2 L 7 = 7,7 -(ethane-1,1-diyl)bis(quinolin-8-ol), Ln III = Eu, Tb, Gd) [19] Each of the terminal Ni II ions in the above complexes [11][12][13][14][15][16][17][18][19][20][21][22][23][24] is coordinated to three phenolato oxygen atoms and three nitrogen atoms, consisting of in situ formed (NiL) − metalloligand. The coordination geometry around the Ni II ions is distorted octahedral except in the case of [{Ni{L 7 ) 1.5 } 2 Ln(OH)] [19] in which the N 3 O 3 atoms create a regular trigonal-antiprismatic geometry around the Ni II ions.…”

Syntheses and Properties of Three Types of 3,4‐Dichlorobenzoate‐based Ni(II)‐Ln(III) Heterometallic Clusters

“…The data can be fitted by the Debye model, giving rise to the α values of 0.09000–0.25497 for all temperatures (Table S10). These α values imply a fairly wide distribution of the magnetic relaxation times . A single relaxation process is consistent with only one type of coordination environment of Dy(III) in the crystal structure of 6 (Ni 2 Dy 2 ) .…”

The Exploration and Analysis of the Magnetic Relaxation Behavior in Three Isostructural Cyano-Bridged 3d–4f Linear Heterotrinuclear Compounds

“…Owing to the coordination ability of the sterically hindered ligands and the difficulty of controlling the coordination orientation, the low-coordinate lanthanide compounds with an axial symmetry are more difficult to obtain. Several reported cases include the nearly linear 2-coordinate (D ∞h ) [21], the equatorially coordinated triangle (C 3 ) [22], the trigonal-pyramidal (pseudo-C 3 ) [23], the five-coordinate [24], and the six-coordinate complexes [9,13,20,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41].…”

“…Considerable energy barriers under zero direct-current (dc) field have been discovered in octahedrally coordinated Dy-containing systems with one or two especially short Dy=C, Dy-N, Dy-O, and Dy-F bonds, such as a monometallic dysprosium(III) bis(methanediide) (U eff = 813 K) [9], a mononuclear six-coordinate dysprosium complex with trigonal-prismatic coordination geometry (U eff = 190 K) [25], a dysprosium thiolate cage (U eff = 66 K) [26], a Dy5 pyramid (U eff = 528 K) [20], a {Dy 4 K 2 } cluster (U eff = 692 K) [27], and the first dysprosium complex with a terminal fluoride ligand (U eff = 760 K) [28]. Relatively lower zero-field energy barriers have been acquired in some six-coordinate Dy-containing examples with a coordination geometry substantially deviated from the ideal octahedron (O h ), such as a trigonal antiprism (U eff = 11 and 14 K) [29], a distorted trigonal prism (U eff = 159 K) [30] and an axially compressed octahedron (for the diluted sample, U eff = 75 K) [31]. Only field-induced energy barriers or even no relaxation parameters could be deduced from the alternating-current (ac) measurements in most of the six-coordinate complexes with more uniform bond lengths [13,[32][33][34][35][36][37][38][39][40][41].…”