Abstract
The redox chemistry of [Cp*Fe(eta(5)-As-5)] (1, Cp* = eta(5)-C5Me5) has been investigated by cyclic voltammetry, revealing a redox behavior similar to that of its lighter congener [Cp*Fe(eta(5)-P-5)]. However, the subsequent chemical reduction of 1 by KH led to the formation of a mixture of novel As-n scaffolds with n up to 18 that are stabilized only by [Cp*Fe] fragments. These include the ...
Abstract
The redox chemistry of [Cp*Fe(eta(5)-As-5)] (1, Cp* = eta(5)-C5Me5) has been investigated by cyclic voltammetry, revealing a redox behavior similar to that of its lighter congener [Cp*Fe(eta(5)-P-5)]. However, the subsequent chemical reduction of 1 by KH led to the formation of a mixture of novel As-n scaffolds with n up to 18 that are stabilized only by [Cp*Fe] fragments. These include the arsenic-poor triple-decker complex [K(dme)(2)][{Cp*Fe(mu,eta(2:2)-As-2)}(2)] (2) and the arsenic-rich complexes [K(dme)(3)](2)[(Cp*Fe)(2)(mu,eta(4:4)-As-10)] (3), [K(dme)(2)](2)[(Cp*Fe)(2)(mu,eta(2:2:2:2)-As-14)] (4), and [K(dme)(3)](2)[(Cp*Fe)(4)(mu(4),eta(4:3:3:2:2:1:1)-As-18)] (5). Compound 4 and the poly-arsenide complex 5 are the largest anionic As-n ligand complexes reported thus far. Complexes 2-5 were characterized by single-crystal X-ray diffraction, H-1 NMR spectroscopy, EPR spectroscopy (2), and mass spectrometry. Furthermore, DFT calculations showed that the intermediate [Cp*Fe(eta(5)-As-5)](-), which is presumably formed first, undergoes fast dimerization to the dianion [(Cp*Fe)(2)(mu,eta(4:4)-As-10)](2-).
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