This work illustrates that manganese(V) nitrido complexes are able to undergo a coordination-induced spin-state change by altering the ligand field from trigonal to tetragonal symmetry. For the reversible coordination of acetonitrile to trigonal [(TIMEN(xyl))Mn(N)](2+) (1; high-spin S = 1; with TIMEN(xyl) = tris[2-(3-xylylimidazol-2-ylidene)ethyl]-amine), a temperature-dependent coordination-induced spin-state switch is established. Starting from the manganese(V) nitrido complex 1, the synthesis and characterization of a series of octahedral, low-spin (S = 0) manganese(V) nitrido complexes of the type [(TIMEN(xyl))Mn(N)(L)](n+) (L = MeCN (2), (t)BuNC (3), CN(-) (4), NCS(-) (5), F(-) (6), μ-{Ag(CN)2}(-) (7), with n = 1, 2) is described. These represent the first examples of d(2) transition metal complexes showing a coordination-induced spin-state change. Spectroscopic, as well as ligand-field theory and density functional theory studies suggest a transition from a 2 + 2 + 1 orbital splitting in the trigonal case to a 1 + 2 + 1 + 1 splitting in tetragonal symmetry as the origin of the coordination-induced spin-state change.
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http://dx.doi.org/10.1021/acs.inorgchem.5b00112 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.
Electron spin plays a critical role in chemical processes, particularly in reactions involving metal complexes with unpaired electrons. However, more definitive state-to-state experiments are needed to better elucidate the role of electronic spin. Herein, we chose nickel (II) 5,10,15,20-tetrakis(pentafluorophenyl) porphyrin 1 as a catalyst, which allows switching from a low spin to a high spin state of Ni (II) center through an axial pyridine coordination, for electrocatalytic hydrogen evolution reaction (HER).
View Article and Find Full Text PDFSmall
January 2025
Departamento de Química Física, Universidad de Sevilla, c/ Prof. García González, s/n, Sevilla, 41012, Spain.
Dalton Trans
May 2024
Department of Chemistry, Inorganic Chemistry, University of Bayreuth, 95447 Bayreuth, Germany.
The simultaneous presence of different electrophores provides an interesting playground for responsive materials. Herein, we present the incorporation of a twice-reversibly oxidizable tetrathiafulvalene (TTF) unit into a binucleating ligand, bridging two metal centers in a fully conjugated plane. A two-step synthesis scheme gave the D symmetric Schiff base-like ligand HL in moderate yields from which the corresponding copper(II) [Cu2L], nickel(II) [Ni2L], [Ni2L(py)4] and iron(II) complexes [Fe2L(py)4], [Fe2L(dmap)4] and [Fe2L(bpee)2]·1 Tol could be obtained.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
July 2024
Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510006, P. R. China.
Integrating controllable spin states into single-molecule magnets (SMMs) enables precise manipulation of magnetic interactions at a molecular level, but remains a synthetic challenge. Herein, we developed a 3d-4f metallacrown (MC) magnet [DyNi(quinha)(sal)(py)](ClO) ⋅ 4HO (Hquinha=quinaldichydroxamic acid, Hsal=5-chlorosalicylaldehyde) wherein a square planar Ni is stabilized by chemical stacking. Thioacetal modification was employed via post-synthetic ligand substitutions and yielded [DyNi(quinha)(saldt)(py)](ClO) ⋅ 3HO (Hsaldt=4-chloro-2-(1,3-dithiolan-2-yl)phenol).
View Article and Find Full Text PDFAngew Chem Int Ed Engl
April 2023
School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland.
Reversible proton-induced spin state switching of an Fe complex in solution is observed at room temperature. A reversible magnetic response was detected in the complex, [Fe (sal 323)]ClO (1), using Evans' method H NMR spectroscopy which indicated cumulative switching from low-spin to high-spin upon addition of one and two equivalents of acid. Infrared spectroscopy suggests a coordination-induced spin state switching (CISSS) effect, whereby protonation displaces the metal-phenoxo donors.
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