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Verfasst von:Ahmed, Naushad [VerfasserIn]   i
 Sharma, Tanu [VerfasserIn]   i
 Spillecke, Lena [VerfasserIn]   i
 Koo, Changhyun [VerfasserIn]   i
 Ansari, Kamal Uddin [VerfasserIn]   i
 Tripathi, Shalini [VerfasserIn]   i
 Caneschi, Andrea [VerfasserIn]   i
 Klingeler, Rüdiger [VerfasserIn]   i
 Rajaraman, Gopalan [VerfasserIn]   i
 Shanmugam, Maheswaran [VerfasserIn]   i
Titel:Probing the origin of ferro-/antiferromagnetic exchange interactions in Cu(II)-4f complexes
Verf.angabe:Naushad Ahmed, Tanu Sharma, Lena Spillecke, Changhyun Koo, Kamal Uddin Ansari, Shalini Tripathi, Andrea Caneschi, Rüdiger Klingeler, Gopalan Rajaraman, and Maheswaran Shanmugam
E-Jahr:2022
Jahr:March 29, 2022
Umfang:16 S.
Fussnoten:Gesehen am 15.07.2022
Titel Quelle:Enthalten in: Inorganic chemistry
Ort Quelle:Washington, DC : American Chemical Society, 1962
Jahr Quelle:2022
Band/Heft Quelle:61(2022), 14, Seite 5572-5587
ISSN Quelle:1520-510X
Abstract:The mechanistic investigations between Cu(II) and the anisotropic lanthanides (Ln(III)) are not much explored to date. This is due to the complicated energy spectrum which arises due to the orbital angular momentum of anisotropic lanthanides. Interestingly, the exchange coupling J in Ln(III)-Cu(II) systems was found to be antiferromagnetic for <4f7 metal ions and ferromagnetic for ≥4f7 metal ions, while the net magnitude of JTotal strength gradually decreases moving from f1 to f13. While this is established in several examples, the reason for this intriguing trend is not rationalized. In this article, we have taken up these challenging tasks by synthesizing a family of complexes with the general molecular formula [Cu2Ln(HL)4(NO3)](NO3)2, where Ln = La (1-La), Ce (2-Ce), Pr (3-Pr), Gd (4-Gd), Tb (5-Tb), Dy (6-Dy), and Ho (7-Ho) and HL = C15H15N1O3; (2-methoxy-6-[(E)-2′-hydroxymethyl-phenyliminomethyl]-phenolate) is a monodeprotonated tridentate Schiff base ligand. Detailed dc magnetic susceptibility measurements performed for all the complexes reveal that the Cu(II) ion is coupled ferromagnetically to the respective Ln(III) ion, which has more than seven electrons in the 4f shell, while an antiferromagnetic coupling is witnessed if Ln(III) has less than seven electrons. The strength of the exchange coupling constant was quantitatively determined for representative complexes from the high-field/high-frequency electron paramagnetic resonance spectroscopy which follows the order of 4-Gd (1.50(10) cm-1) > 5-Tb (1.18(10) cm-1) > 6-Dy (0.56(10) cm-1 based on the −2JCu−Ln(SCu1→·JLnz→+SCu2→·JLnz→) spin Hamiltonian. The increased axiality in 5-Tb and 6-Dy due to the presence of 3d ions in the near vicinity of an oblate ion and the increased exchange coupling strength between Cu(II) and Tb(III) or Dy(III) is the ideal combination to stabilize magnetic bistability in these complexes in the absence of an external magnetic field with the effective energy barrier of 15.7 K (τo = 2.49 × 10-6 s) and 12.6 K (τo = 1.70 × 10-5 s), respectively. To rationalize this experimental trend, we have performed ab initio CASSCF and DFT calculations. To compute the J values, we have employed POLY_ANISO routines and utilized the computed data to establish the generic mechanism of magnetic coupling in {Cu-Ln-Cu} motifs. These mechanistic findings reveal the importance of 5d orbitals and their energy with respect to the dx2-y2 orbital of Cu(II) ions in controlling the magnetic coupling of {Cu-4f} complexes.
DOI:doi:10.1021/acs.inorgchem.2c00065
URL:Bitte beachten Sie: Dies ist ein Bibliographieeintrag. Ein Volltextzugriff für Mitglieder der Universität besteht hier nur, falls für die entsprechende Zeitschrift/den entsprechenden Sammelband ein Abonnement besteht oder es sich um einen OpenAccess-Titel handelt.

Volltext: https://doi.org/10.1021/acs.inorgchem.2c00065
 DOI: https://doi.org/10.1021/acs.inorgchem.2c00065
Datenträger:Online-Ressource
Sprache:eng
K10plus-PPN:1810597439
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