Understanding Factors that Control the Structural (Dis)Assembly of Sulphur-Bridged Bimetallic Sites

Autor: Alrefai, Riyadh, Eggenweiler, Henri, Schubert, Hartmut, Berkefeld, Andreas
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Zdroj: Inorganics, Vol 7, Iss 4, p 42 (2019)
Inorganics
Volume 7
Issue 4
ISSN: 2304-6740
Popis: Bimetallic structures of the general type [M2(µ
S)2] are omnipresent in nature, for biological function [M2(µ
S)2] sites interconvert between electronically distinct, but isostructural, forms. Different from structure-function relationships, the current understanding of the mechanism of formation and persistence of [M2(µ
S)2] sites is poorly developed. This work reports on bimetallic model compounds of nickel that interconvert between functional structures [Ni2(µ
S)2]+/2+ and isomeric congeners [2{&kappa
S&ndash
Ni}]2+/+, S = Aryl-S&minus
in which the nickel ions are geometrically independent. Interconversion of the two sets of structures was studied quantitatively by UV&ndash
VIS absorption spectroscopy and cyclic voltammetry. Assembly of the [Ni2(µ
S)2]+ core from [2{&kappa
Ni}]+ is thermodynamically and kinetically highly preferred over the disassembly of [Ni2(µ
S)2]2+ into [2{&kappa
Ni}]2+. Labile Ni-&eta
2/3-bonding to aromatic &pi
systems of the primary thiophenol ligand is critical for modeling (dis)assembly processes. A phosphine coligand mimics the role of anionic donors present in natural sites that saturate metal coordination. Three parameters have been identified as critical for structure formation and persistence. These are, first, the stereoelectronic properties of the metals ions, second, the steric demand of the coligand, and, third, the properties of the dative bond between nickel and coligand. The energies of transition states connecting functional and precursor forms have been found to depend on these parameters.
Databáze: OpenAIRE
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