Enhancing Ueff in oxime-bridged [MnIII6LnIII2] hexagonal prisms

Abstract

The first 3d-4f clusters built using derivatised salicylaldoximes (R-saoH(2)) describe unusual hexagonal prisms. Replacement of the paramagnetic Gd(III) ions with diamagnetic Ln(III) ions allows for a more thorough understanding of the magnetic properties, whilst replacement with Tb(III) doubles U(eff).

From antiferromagnetic to ferromagnetic exchange in a family of oxime-based MnIII dimers: a magneto-structural study

“…[28][29][30][31][32][33][34] A highly promising family of ligands for constructing magnetically interesting clusters based on Mn III are the phenolic oximes (R-saoH 2 , Scheme 1). [40][41][42] Our most recent research attempts have therefore focused on deliberately targeting Mn III clusters with the R-saoH 2 family of ligands whose building blocks are not [Mn III 3 O(R-sao) 3 ] + triangles. 37 Nearest neighbour magnetic exchange is dominated by the twisting of the -N-Omoiety of the phenolic oxime and the sign and magnitude of the pairwise exchange can be controlled via chemical substitution at the oximic C-atom.…”

[MnIII6O3Ln2] Single‐Molecule Magnets: Increasing the Energy Barrier Above 100 K

“…Numerous synthetic approaches have been developed to reach this goal, among them the insertion of anisotropic high-spin lanthanide ions [1b] into mono-and polynuclear 4f metal complexes, [3,4] but also in variety of heterometallic 3d-4f systems. [5, 6] To date, the record for the barrier to magnetization relaxation for a 3d-4f complex, 74 K, has been held by a high-nuclearity complex with an {Mn 21 Dy} core.[5]Here we report the first examples of a new family of heterometallic lanthanide-manganeseA C H T U N G T R E N N U N G (III) SMMs with an {Mn III 6 O 3 Ln 2 } core (1 and 2; Ln= La and Tb respectively); these complexes were synthesized by means of a facile twostep self-assembly process (Scheme 1) and they display remarkably high SMM energy barriers, reaching 103 K for 2.As summarized in Scheme 1, stoichiometric amounts of MnCl 2 ·4 H 2 O and the salicylaldoxime ligand (Scheme 2) in methanol were mixed with tetraethylammonium hydroxide before adding two equivalents of solid lanthanide nitrate (1:. After 12 h of stirring, concentration on rotary evaporator and filtration, the resulting black solution was layered by diethyl ether.…”

“…Considering the S T = 12 ground state of 1 and D/k B = DS 2 T /k B = 32.8 K, the D parameter [2] can be estimated at about À0.23 K. The SMM energy barrier of 103 K found in 2 is one of the highest that have ever been reported and the largest measured among the 3d and 3d-4f SMMs. [5] It is more than three times larger than for 1 as a result of a simultaneous increase of both magnetic anisotropy and effective spin ground state achieved by the replacement of the diaA C H T U N G T R E N N U N G magnetic La III by paramagnetic and anisotropic Tb III ions. Above 1.8 K, the quantum relaxation pathway does not influence the thermally activated process as proved by the ac measurements performed under small dc fields, which do not show a slowing down of the relaxation ( Figure S12, S13, S18, and S19 in the Supporting Information).…”

“…These hypotheses have been verified by the fit of the cT versus T data to the theoretical susceptibility calculated by MAG-PACK program, [9] and treating the intercomplex magnetic interactions in the frame of the mean-field approximation. [10] As shown in Figure 2 and Figure S5 in the Supporting Information, the theoretical curve (red line) is well superposed to the experiment data allowing for a good estimation of J 1 / k B = + + 1.1(2) K, J 2 /k B = + + 6.0(5) K, zJ'/k B = À0.011(2) K [11] and g = 1.99 (5). This result indicates that 1 possesses an S T = 12 spin ground state with a low-lying S = 11 excited state at about 6.3 K above in energy ( Figure S6 in the Supporting Information).…”

“…[5,6] To date, the record for the barrier to magnetization relaxation for a 3d-4f complex, 74 K, has been held by a high-nuclearity complex with an {Mn 21 Dy} core. [5] Here we report the first examples of a new family of heterometallic lanthanide-manganeseA C H T U N G T R E N N U N G (III) SMMs with an {Mn III 6 O 3 Ln 2 } core (1 and 2; Ln= La and Tb respectively); these complexes were synthesized by means of a facile twostep self-assembly process (Scheme 1) and they display remarkably high SMM energy barriers, reaching 103 K for 2.…”