Mn^III ₂Ln^III ₂ (Ln = Gd, Dy, Ho) Complexes From The Initial Employment of 1,3-Propanediol In Mixed 3d/4f Metal Cluster Chemistry

Abstract

The initial employment of 1,3-propanediol (pdH 2) in the synthesis of 3d/4f metal clusters has afforded a new family of tetranuclear [Mn 2 Ln 2 O 2 {(CH 3) 3 CCO 2 } 8 {(CH 3) 3 CCO 2 H} 2 (pdH 2) 2 ] (Ln = Dy, 1; Gd, 2; Ho, 3) complexes. Compounds 1-3 represent new additions to the small family of Mn III 2 Ln 2 clusters possessing planar or diamond-like cores. Variable-temperature, dc and ac magnetization measurements were performed on compounds 1-3 and revealed the existence of very weak antiferromagnetic exchange interactions between the metal centers leading to a ground state spin value S = 5 in case of 2•2(CH 3) 3 CCO 2 H•2H 2 O.

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.…”

Metallo‐Ligand Based 3d/4f Coordination Polymers: Synthesis, Structure and Magnetic Properties

“…There has been an increasing interest in the synthesis and characterization of new 3d/4f complexes mainly due to their interesting magnetic properties which most often originate from the inherent uniaxial anisotropy of the 4f ions [1–9] . The combination of 3d and 4f metal ions may result in either discrete polynuclear metal complexes [10–35] exhibiting high spin ground states and in several occasions single‐molecule magnet behavior or in polymeric species [36–45] …”