Assisted Self‐Assembly to Target Heterometallic Mn‐Nd and Mn‐Sm SMMs: Synthesis and Magnetic Characterisation of [Mn₇Ln₃(O)₄(OH)₄(mdea)₃(piv)₉(NO₃)₃] (Ln=Nd, Sm, Eu, Gd)**

Abstract

In an assisted self-assembly approach starting from the [Mn 6 O 2 (piv) 10 (4-Me-py) 2 (pivH) 2 ] cluster a family of MnÀ Ln compounds (Ln = PrÀ Yb) was synthesised. The reaction of [Mn 6 O 2 (piv) 10 (4-Me-py) 2 (pivH) 2 ](1) with N-methyldiethanolamine (mdeaH 2 ) and Ln(NO 3 ) 3 • 6H 2 O in MeCN generally yields two main structure types: for Ln = TbÀ Yb a previously reported Mn 5 Ln 4 motif is obtained, whereas for Ln = PrÀ Eu a series of Mn 7 Ln 3 clusters is obtained. Within this series the Gd III analogue represents a special case because it shows both structural types as well as a third Mn 2 Ln 2 inverse butterfly motif. Variation in reaction conditions allows access to different structure types across the whole series. This prompts further studies into the reaction mechanism of this cluster assisted self-assembly approach. For the Mn 7 Ln 3 analogues reported here variable-temperature magnetic susceptibility measurements suggest that antiferromagnetic interactions between the spin carriers are dominant. Compounds incorporating Ln = Nd III (2), Sm III (3) and Gd III (5) display SMM behaviour. The slow relaxation of the magnetisation for these compounds was confirmed by ac measurements above 1.8 K.

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.…”

Synthesis, structures, and magnetic properties of butterfly-shaped hexanuclear [FeIII4LnIII2] single-molecule magnets

“…Since the first observation of SMM behavior in a Cu II 2 Tb III 2 coordination compound, 14,15 the construction and characterization of polynuclear 3d–4f coordination clusters have become a very active research area. 16 However, research on 3d–4f SMMs has mainly been focused on Ln–Mn, 17–21 Ln–Co, 22–27 Ln–Ni, 28–32 and Ln–Zn 33,34 heterometallic systems and there are relatively few reports on Ln–Fe complexes. Although some Ln III –Fe III heterometallic coordination clusters have been reported, only a few exhibit slow magnetization relaxation in the absence of a static field.…”

Cooperative Effects in Heterometallic Complexes

“…[5,7,12,13,15,22] There are two reviews: one is focused on elucidating the magnetic benefits and challenges of cooperativity within 3d-4f based coordination clusters of archetypical butterfly type, [21] and the other one highlights more generally the advancement of inorganic coordination chemistry by spectroscopy of isolated molecules in view of the applied methods and the achieved applications. [18] Three communications, [3,12,22] one concept article [8] and 17 full papers [1,2,[4][5][6][7][9][10][11][13][14][15][16][17]19,20,23] document and discuss particular 3MET species and their relevance for our understanding of the TM interactions within. A contribution on the development and application of a complete active space spin-orbit configuration interaction program designed for molecule magnets deserves special mention: this manuscript appears in a more specialized sister journal.…”

“…The current special issue of Chemistry -a European Journal issue comprises 23 contributions in total, 17 of which stem from work that was conducted within the framework of the 3MET.de center, [1][2][3][4]6,[8][9][10][11]14,[16][17][18][19][20][21]23] and six from outside. [5,7,12,13,15,22] There are two reviews: one is focused on elucidating the magnetic benefits and challenges of cooperativity within 3d-4f based coordination clusters of archetypical butterfly type, [21] and the other one highlights more generally the advancement of inorganic coordination chemistry by spectroscopy of isolated molecules in view of the applied methods and the achieved applications.…”