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Publication: Templated syntheses of heterometal tungsten-cobalt-sulfur clusters with different nuclearities

Prof Xudong Chen published his research papers in DALTON TRANSACTIONS (202005,49(17),5523-5530)


A series of new W-Co-S clusters have been synthesized utilizing the complex [Et4N][(Tp*)WS3] (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate(1-)) as the synthetic template, by rational control of the stoichiometry of reactants and by employment of a reductant or precipitant as an auxiliary reagent. By solubility control or addition of a precipitant to avoid the involvement of Cl- in the reaction, the cluster [(Tp*)WS3](2)Co (2) could be obtained. With different ratios of the Co source to the template, together with the use of an appropriate amount of reducing reagent, clusters [{(Tp*)WS3}(2)Co](1-) (3) and [{(Tp*)WS3}(2)Co2Cl](1-) (4) could be synthesized as their Et4N+ salts, and [{(Tp*)WS3}(2)Co4Cl2(DMF)](1-) (5) could be isolated as its [Co(DMF)(6)](2+) salt. A common structural feature of these clusters is that they all have a pair of [(Tp*)WS3] templates chelating different numbers of Co atoms to form W-Co-S clusters with distinct nuclearities. The clusters [(Tp*)WS3](2)Co (2) and [{(Tp*)WS3}(2)Co](1-) (3) both have one Co atom chelated by two [(Tp*)WS3] templates, and the difference lies in not only the oxidation states but also the fact that the Co atom in 2 adopts an octahedral coordination environment while that in 3 bears a tetrahedral coordination sphere, which means that the [(Tp*)WS3] template is tri-dentate in 2 and bi-dentate in 3. The cluster [{(Tp*)WS3}(2)Co2Cl](1-) (4) has two Co atoms chelated by a pair of [(Tp*)WS3] templates, in which one of the Co atoms is also terminally bound by a Cl- ligand. There are four Co atoms chelated by two [(Tp*)WS3] templates in the cluster [{(Tp*)WS3}(2)Co4Cl2(DMF)](1-) (5), two of which are bound terminally by the Cl- ligands. Studies of redox properties by cyclic voltammetry indicate the existence of two reversible redox pairs related to clusters 2 and 3, respectively.