Arsenic-Rich Polyarsenides Stabilized by Cp*Fe Fragments

Angewandte Chemie - International Edition

5 years ago

Arsenic-Rich Polyarsenides Stabilized by Cp*Fe Fragments

Alexander V. Virovets, Gabor Balázs, Felix Riedlberger, Monika Schmidt, Eugenia V. Peresypkina, David Konieczny, Michael Bodensteiner, Hannes Krauss, Manfred Scheer

The redox chemistry of [Cp*Fe(η5-As5)] (1, Cp*=η5-C5Me5) has been investigated by cyclic voltammetry, revealing a redox behavior similar to that of its lighter congener [Cp*Fe(η5-P5)]. However, the subsequent chemical reduction of 1 by KH led to the formation of a mixture of novel Asn 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(μ,η2:2-As2)}2] (2) and the arsenic-rich complexes [K(dme)3]2[(Cp*Fe)2(μ,η4:4-As10)] (3), [K(dme)2]2[(Cp*Fe)2(μ,η2:2:2:2-As14)] (4), and [K(dme)3]2[(Cp*Fe)4(μ4,η4:3:3:2:2:1:1-As18)] (5). Compound 4 and the polyarsenide complex 5 are the largest anionic Asn ligand complexes reported thus far. Complexes 2–5 were characterized by single-crystal X-ray diffraction, 1H NMR spectroscopy, EPR spectroscopy (2), and mass spectrometry. Furthermore, DFT calculations showed that the intermediate [Cp*Fe(η5-As5)]−, which is presumably formed first, undergoes fast dimerization to the dianion [(Cp*Fe)2(μ,η4:4-As10)]2−. The chemical reduction of [Cp*Fe(η5-As5)] (1) with KH leads to a mixture of polyarsenic ligand complexes, such as [K(dme)2][{Cp*Fe(μ,η2:2-As2)}2] (2), [K(dme)3]2[(Cp*Fe)2(μ,η4:4-As10)] (3), [K(dme)2]2[(Cp*Fe)2(μ,η2:2:2:2-As14)] (4), and [K(dme)3]2[(Cp*Fe)4(μ4,η4:3:3:2:2:1:1-As18)] (5). Complexes 4 and 5 are the largest anionic polyarsenic ligand complexes reported thus far. Compound 1 is therefore a powerful starting material for generating polyarsenic moieties.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/anie.201702903