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Heterometallic CuCd and Cu2Zn complexes with o-vanillin and its Schiff-base derivative: slow magnetic relaxation and catalytic activity associated with Cu(II) centres
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Resumo(s)
Abstract
In this work, two novel heterometallic mixed-ligand mixed-anion complexes [CuIICdIIClL(o-Van) (OAc)]·3H2O (1) and [CuII2ZnIICl2L2(o-Van)(OAc)] (2) were prepared by reacting fine copper powder and Cd(II) or Zn(II) acetate with an ethanol solution of the Schiff-base ligand HL formed in situ in the condensation reaction of 2-hydroxy-3-methoxy-benzaldehyde (o-VanH) and CH3NH2·HCl. The compounds were thoroughly characterized by elemental analysis, FT-IR, UV/Vis and EPR spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction, revealing the neutral molecular nature of both the compounds. Catalytic properties of 1 and 2 were studied in the oxidation of hydrocarbons with H2O2 under mild conditions, showing the maximum reaction rate of 4 × 10−5 M s−1 and TOF up to 640 h−1. Both compounds undergo complex transformations in solution as evidenced by kinetic analysis and time-dependent UV/Vis spectroscopy, indicating that the reduced Cu(I) form of 1 is unexpectedly unfavorable. Complex 1 demonstrates slow magnetic relaxation dominated by the direct relaxation process between T = 1.8 and 7 K under an external DC field of 0.2 and 0.4 T, a very rarely observable effect in the coordination compounds of Cu(II).
Complex 2 possesses weak ferromagnetism (J = 4.50 cm−1, zJ’ = −0.201 cm−1 for H = −JS1S2 formalism) occurring through the Cu–O–Cu pathways. Theoretical CASSCF, DFT and TDDFT calculations were applied to investigate the electronic structures of 1 and 2 and rationalize their behavior in solution.
Descrição
This work was funded by the Ministry of Education and Science of Ukraine (grant for the perspective development of the scientific direction “Mathematical sciences and natural sciences” at the Taras Shevchenko National University of Kyiv). The authors acknowledge the OBLIVION Supercomputer (HPC Centre of the University of Évora, Portugal) funded by the “Enabling Green E-science for the SKA Research Infrastructure (ENGAGE SKA)”, reference POCI-01-0145-FEDER-022217 (COMPETE 2020), and Foundation for Science and Technology (FCT), Portugal. This work was supported by computational resources from FCT I.P. under projects 2024.02988.CPCA.A0
(O.V.N.) and 2023.10683.CPCA.A1 (D.S.N.).
Palavras-chave
Heterometallic Schiff-base derivative Magnetic relaxation Catalytic activity POCI-01-0145-FEDER-022217
Contexto Educativo
Citação
Vassilyeva, O. Y., Nesterova, O. V., Bienko, A., Komarnicka, U. K., Buvaylo, E. A., Vasylieva, S. M., Skelton, B. W., Neterov, D. S. (2025). Heterometallic CuCd and Cu2Zn complexes with o-vanillin and its Schiff-base derivative: slow magnetic relaxation and catalytic activity associated with Cu(II) centres. Dalton Transactions, 54, 6117–6132. https://10.1039/d4dt03571b
Editora
Royal Society of Chemistry