Magneto-thermal properties and slow magnetic relaxation in Mn(ii)Ln(iii) complexes: influence of magnetic coupling on the magneto-caloric effect

Abstract

A family of Mn(II)Ln(III) dinuclear and tetranuclear complexes (Ln = Gd and Dy) has been prepared from the compartmental ligands N,N’-dimethyl-N,N’-bis(2-hydroxy-3-formyl-5-bromobenzyl)ethylenediamine (H2L1) and N,N’,N”-trimethyl-N,N”-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H2L2). The Mn(II)Gd(III) complexes exhibit antiferromagnetic...

Field induced slow magnetic relaxation in a linear homotrinuclear manganese heterospin coordination compound with S = 7/2 ground state and intriguing spin density distribution

“…And even in the LS state Mn( ii ) is not a good SMM candidate because for S = 1/2 spin systems the magnetic anisotropy D parameter is undefined. SMM properties for Mn( ii ) compounds were reported earlier in the heteronuclear compounds with other metals, for example with lanthanides, 18,19 mixed valence Mn( ii / iii / iv ), and Cu II /Mn II . 20 Homopolynuclear Mn( ii ) compounds with slow magnetization relaxation have not been reported to the best of our knowledge.…”

Linear versus Bent 3d/4f-Heterometallic Clusters: The Carboxylate Effect on the Metal Topology and Magnetic Properties of Two {MnIII2Dy2} Complexes Supported by N-Naphthalidene-o-Aminophenol

“…The room-temperature χ M T values for well-dried 1 (34.01 cm 3 K mol –1 ) and 2 (33.28 cm 3 K mol –1 ) are in excellent agreement with the expected value of 34.34 cm 3 K mol –1 for two Dy III ( 6 H 15/2 , free ion; S = 5/2, L = 5, g J = 4/3; χ M T = 14.17 cm 3 K mol –1 ) and two high-spin Mn III ( S = 2 with g = 2.0) noninteracting ions. Upon cooling, the χ M T products of the two complexes decrease slowly in the 300–50 K temperature range and then more rapidly reaching the values of 9.62 ( 1 ) and 3.49 ( 2 ) cm 3 K mol –1 at 2.0 K. The decrease of χ M T in both cases is likely due to a combination of intramolecular Mn···Dy and Dy···Dy antiferromagnetic exchange interactions and depopulation of the m J sublevels of the ground J state of the Dy III ions. − Given the similar metrical parameters in 1 and 2 (Mn–N/O and Dy–O bond distances and Mn–O–Dy and Dy–O–Dy angles), the observed difference in the shapes of the χ M T vs T plots and the fact that the χ M T value of 2 is much lower than that of 1 at 2 K could be attributed to the dissimilar coordination polyhedra of the Dy III atoms in the two complexes and, subsequently, the different degree of interaction of the J ground manifold with the crystal field. , A fit of the experimental data to the Curie–Weiss law in the 5–300 K region gives a Curie constant, C , of 34.81 (for 1 ) and 34.44 (for 2 ) cm 3 K mol –1 and a Weiss temperature, θ, of −7.10 (for 1 ) and −12.65 (for 2 ) K (Figure ). The negative values of θ indicate the presence of antiferromagnetic interactions between the Mn III ···Dy III and (possibly) Dy III ···Dy III pairs.…”

Ferromagnetically coupled CoII2LnIII2 complexes (where LnIII = Ho, Er, Yb): experimental and theoretical investigations

“…[1][2][3][4][5][6][7][8] The nature and the strength of magnetic exchange interactions were noticed to play a crucial role in modulating the slowmagnetic relaxation (a typical signature of single-molecule magnets, SMMs) and magnetothermal (magnetocaloric effect, MCE) properties of multinuclear metal clusters. [9][10][11][12][13][14][15][16][17][18][19][20][21] On the one hand, molecules with SMM signatures are the proposed candidate for technological applications such as moleculebased spintronics and high-density storage devices. Conversely, molecules with MCE properties are the proposed candidate to achieve ultra-cooling and can replace expensive liquid 3 He.…”

“…[25][26][27] In general the 4f and 3d-4f metal clusters consisting of isotropic metal ions such as Gd III (S = 7/2, 8 S 7/2 ), Mn II , Fe III , Co II , Ni II , and Cu II are widely used to investigate MCE behavior. 12,13,[28][29][30][31][32][33][34][35][36][37][38] Although the high spin and small or negligible magnetic anisotropy are the pre-requisite to achieve magnetothermal properties, a recent report on [{Dy(OAc) 3 (H 2 -O) 2 } 2 ]•4H 2 O (ref. 39) shows that anisotropic metal complexes can also be proposed for MCE properties.…”