Two-Dimensional Networks of Lanthanide Cubane-Shaped Dumbbells

Abstract

The syntheses, structures, and magnetic properties are reported for three new lanthanide complexes, [Ln(III)(4)(mu(3)-OH)(2)(mu(3)-O)(2)(cpt)(6)(MeOH)(6)(H(2)O)](2) (Ln = Dy (1.15MeOH), Ho (2.14MeOH), and Tb (3.18MeOH)), based on 4-(4-carboxyphenyl)-1,2,4-triazole ligand (Hcpt). The three complexes were confirmed to be isomorphous by infrared spectroscopy and single-crystal X-ray diffraction. The crystal structure of 1 reveals that the eight-coordinate metal centers are organized in two cubane-shaped moieties composed of four Dy(III) ions each. All metal centers in the cubane core are bridged by two mu(3)-oxide and two mu(3)-hydroxide asymmetrical units. Moreover, each cubane is linked to its neighbor by two externally coordinating ligands, forming the dumbbell {Dy(III)(4)}(2) moiety. Electrostatic interactions between the ligands of the triazole-bridged dimers form an extended supramolecular two-dimensional arrangement analogous to a metal-organic framework with quadrilateral spaces occupied by ligands from axial sheets and by four solvent molecules. The magnetic properties of the three compounds have been investigated using dc and ac susceptibility measurements. For 1, the static and dynamic data corroborate the fact that the {Dy(III)(4)} cubane-shaped core exhibits slow relaxation of its magnetization below 5 K associated with a single-molecule magnet behavior.

3D Organization of Dysprosium Cubanes

“…However, the χ M ЈЈ/χ M Ј ratio is very small (0.07), and a very small part of the sample is able to relax slowly. This is in agreement with what was recently observed in isolated (χ M ЈЈ/χ M Ј = 0.046 [85] and χ M ЈЈ/χ M Ј = 0.036 [87] ) and in 2D lanthanide-based cubane networks (χ M ЈЈ/χ M Ј = 0.083 [86] ). Even if a frequency dependence is seen for [Dy 4 (μ 3 -OH) 3 12 ] ϱ , we do not consider this significant enough to extract dynamic parameters that usually characterize SMMs or SCMs (SCM = single-chain magnet).…”

A salen-type Dy4 single-molecule magnet with an enhanced energy barrier and its analogues

“…Fig. 33 Such a phenomenon is similar to the reported lanthanide complexes. The solid lines correspond to the best fit obtained using two modified Debye functions.…”

In situ ligand formation in the synthesis of an octanuclear dysprosium ‘double cubane’ cluster displaying single molecule magnet features

“…There are two recent reports of Dy 4 cubanes being bridged to form Dy 8 clusters by two μ 1,3 -carboxylates 15 and two triazole(N)-carboxylates(O,O′). 16 On the periphery of each of the two cubane units are five cmnm ligands, all which have a μ 2 -η 2 (N,N′)Dy:η 1 (O)Dy′ coordination mode, where the cmnm ligand chelates to a dysprosium atom via the nitrogen atoms of the nitroso and the imine groups and bridges to another dysprosium ion via the oxygen atom of the nitroso group (Scheme 2, Fig. 1c, Table 1).…”