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Article

A Mixed-Valence Tetra-Nuclear Nickel Dithiolene Complex: Synthesis, Crystal Structure, and the Lability of Its Nickel Sulfur Bonds

Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, 17489 Greifswald, Germany
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Received: 9 March 2020 / Revised: 29 March 2020 / Accepted: 3 April 2020 / Published: 9 April 2020
In this study, by employing a common synthetic protocol, an unusual and unexpected tetra-nuclear nickel dithiolene complex was obtained. The synthesis of the [Ni4(ecpdt)6]2− dianion (ecpdt = (Z)-3-ethoxy-3-oxo-1-phenylprop-1-ene-1,2-bis-thiolate) with two K+ as counter ions was then intentionally reproduced. The formation of this specific complex is attributed to the distinct dithiolene precursor used and the combination with the then coordinated counter ion in the molecular solid-state structure, as determined by X-ray diffraction. K2[Ni4(ecpdt)6] was further characterized by ESI-MS, FT-IR, UV-Vis, and cyclic voltammetry. The tetra-nuclear complex was found to have an uncommon geometry arising from the combination of four nickel centers and six dithiolene ligands. In the center of the arrangement, suspiciously long Ni–S distances were found, suggesting that the tetrameric structure can be easily split into two identical dimeric fragments or two distinct groups of monomeric fragments, for instance, upon dissolving. A proposed variable magnetism in the solid-state and in solution due to the postulated dissociation was confirmed. The Ni–S bonds of the “inner” and “outer” nickel centers differed concurrently with their coordination geometries. This observation also correlates with the fact that the complex bears two anionic charges requiring the four nickel centers to be present in two distinct oxidation states (2 × +2 and 2 × +3), i.e., to be hetero-valent. The different coordination geometries observed, together with the magnetic investigation, allowed the square planar “outer” geometry to be assigned to d8 centers, i.e., Ni2+, while the Ni3+ centers (d7) were in a square pyramidal geometry with longer Ni–S distances due to the increased number of donor atoms and interactions. View Full-Text
Keywords: mixed-valence complex; dithiolene ligand; tetra-nuclear nickel complex; X-ray structure; magnetic moment mixed-valence complex; dithiolene ligand; tetra-nuclear nickel complex; X-ray structure; magnetic moment
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MDPI and ACS Style

Ahmadi, M.; Correia, J.; Chrysochos, N.; Schulzke, C. A Mixed-Valence Tetra-Nuclear Nickel Dithiolene Complex: Synthesis, Crystal Structure, and the Lability of Its Nickel Sulfur Bonds. Inorganics 2020, 8, 27. https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics8040027

AMA Style

Ahmadi M, Correia J, Chrysochos N, Schulzke C. A Mixed-Valence Tetra-Nuclear Nickel Dithiolene Complex: Synthesis, Crystal Structure, and the Lability of Its Nickel Sulfur Bonds. Inorganics. 2020; 8(4):27. https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics8040027

Chicago/Turabian Style

Ahmadi, Mohsen, Jevy Correia, Nicolas Chrysochos, and Carola Schulzke. 2020. "A Mixed-Valence Tetra-Nuclear Nickel Dithiolene Complex: Synthesis, Crystal Structure, and the Lability of Its Nickel Sulfur Bonds" Inorganics 8, no. 4: 27. https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics8040027

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