Octanuclear Heterobimetallic {Ni4Ln4} Assemblies Possessing Ln4 Square Grid [2 × 2] Motifs: Synthesis, Structure, and Magnetism
Octanuclear heterobimetallic complexes, [Ln4Ni4(H3L)4(μ3-OH)4(μ2-OH)4]4Cl·xH2O·yCHCl3 (Dy3+, x = 30.6, y = 2 (1); Tb3+, x = 28, y = 0 (2) ; Gd3+, x = 25.3, y = 0 (3); Ho3+, x = 30.6, y = 3 (4)) (H5L = N 1,N 3-bis(6-formyl-2-(hydroxymethyl)-4-methylphenol)diethylenetriamine) are reported. These ar...
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Veröffentlicht in: | Inorganic chemistry 2016-09, Vol.55 (17), p.8422-8436 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Octanuclear heterobimetallic complexes, [Ln4Ni4(H3L)4(μ3-OH)4(μ2-OH)4]4Cl·xH2O·yCHCl3 (Dy3+, x = 30.6, y = 2 (1); Tb3+, x = 28, y = 0 (2) ; Gd3+, x = 25.3, y = 0 (3); Ho3+, x = 30.6, y = 3 (4)) (H5L = N 1,N 3-bis(6-formyl-2-(hydroxymethyl)-4-methylphenol)diethylenetriamine) are reported. These are assembled by the cumulative coordination action of four doubly deprotonated compartmental ligands, [H3L]2–, along with eight exogenous −OH ligands. Within the core of these complexes, four Ln3+’s are distributed to the four corners of a perfect square grid while four Ni2+’s are projected away from the plane of the Ln4 unit. Each of the four Ni2+’s possesses distorted octahedral geometry while all of the Ln3+’s are crystallographically equivalent and are present in an elongated square antiprism geometry. The magnetic properties of compound 3 are dominated by an easy-plane single-ion anisotropy of the Ni2+ ions [D Ni = 6.7(7) K] and dipolar interactions between Gd3+ centers. Detailed ac magnetometry reveals the presence of distinct temperature-dependent out-of-phase signals for compounds 1 and 2, indicative of slow magnetic relaxation. Magnetochemical analysis of complex 1 implies the 3d and the 4f metal ions are engaged in ferromagnetic interactions with SMM behavior, while dc magnetometry of compound 2 is suggestive of an antiferromagnetic Ni–Tb spin-exchange with slow magnetic relaxation due to a field-induced level crossing. Compound 4 exhibits an easy-plane single-ion anisotropy for the Ho3+ ions and weak interactions between spin centers. |
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ISSN: | 0020-1669 1520-510X |
DOI: | 10.1021/acs.inorgchem.6b01019 |