Synthesis, structure, electrochemistry and magnetism of cobalt-, nickel- and zinc-containing [M₄(OH)₃(H₂O)₂(α-SiW₁₀O_36.5)₂]¹³⁻ (M = Co²⁺, Ni²⁺, and Zn²⁺)

Abstract

Interaction of the trilacunary 9-tungstosilicate [A-α-SiW9O34]10- with cobalt(II), nickel(II) and zinc(II) ions in pH 9 aqueous medium at room temperature led to the formation of the respective M4-containing heteropolytungstates [M4(OH)3(H2O)2(α-SiW10O36.5)2]13-...

Search for Structurally Resembled Mn/Ca Cubane Core of the Oxygen Evolving Complex of Photosystem II Yielded MnIV, MnIII3MnII and MnIII2CaII2Entities: Structure and Magnetism

“…Variables A and B are defined in equations (6) and (7). It should be noted that phenomena such as temperature independent magnetism and axial zero field splitting were not considered, as one would risk over‐parameterization [66,67] …”

“…It should be noted that phenomena such as temperature independent magnetism and axial zero field splitting were not considered, as one would risk overparameterization. [66,67] b…”

Speciation of Transition-Metal-Substituted Keggin-Type Silicotungstates Affected by the Co-crystallization Conditions with Proteinase K

“…Recently, Cs salts of tetrasubstituted sandwich Keggin silicotungstates have been reported. 22 However, different routes for the synthesis of {SiW 10 M 2 } 2 have been used. While the structures reported by Haider et al.…”

“…The UV/vis spectra of Na­{SiW 10 Ni 2 } 2 and Na­{SiW 10 Co 2 } 2 show an absorption maximum at ∼221 nm, with a shoulder at ∼250 nm attributed to the pπ­(O b ) → dπ*­(W) ligand-to-metal charge-transfer (LMCT) transitions typical for the Keggin POTs (Figure S8A). , The visible spectrum of Na­{SiW 10 Co 2 } 2 displays a peak located at ∼512 nm, which is typical for octahedrally coordinated Co II centers (Figure S8B). ,, Considering the pronounced peak at ∼512 nm, time-dependent UV/vis studies were performed in water at pH 6.8 on Na­{SiW 10 Co 2 } 2 in the presence and absence of proteinase K, thereby circumventing potential peak overlap with the protein (Figure S12).…”

“… , The visible spectrum of Na­{SiW 10 Co 2 } 2 displays a peak located at ∼512 nm, which is typical for octahedrally coordinated Co II centers (Figure S8B). ,, Considering the pronounced peak at ∼512 nm, time-dependent UV/vis studies were performed in water at pH 6.8 on Na­{SiW 10 Co 2 } 2 in the presence and absence of proteinase K, thereby circumventing potential peak overlap with the protein (Figure S12). A negligible decrease in absorption can be observed over 240 min for the POT in water in the absence of protein (Figure S11A), whereas a dramatic drop in absorption at ∼512 nm in the presence of proteinase K indicates strong POT–protein interactions via the Co II site upon the formation of POT–protein adducts, which eventually leads to precipitation (Figure S11B).…”