Versatile Coordination of Ag(I) and Cu(I) Ions towards cyclo‐As(5) Ligands

The reactions of the cyclo‐As(5) complex [Cp*Fe(η(5)‐As(5))] (B) with the Ag(I) and Cu(I) salts of the weakly coordinating anion (WCA) [FAl{OC(6)F(10)(C(6)F(5))}(3)](−) ([FAl](−)) are studied. These reactions allow the synthesis of the mononuclear complexes [M(η(5) : η(2)‐B)(2)][FAl] (M=Ag (1), Cu (2)) when a ratio of B/M(FAl) 2 : 1 is used. Compound 1 shows an unusual disorder of the central Ag(I) cation between two π‐coordinating cyclo‐As(5) ligands, which is absent in 2 pointing to a weak interaction of the Ag center towards the cyclo‐As(5) ligands in B. When the ratio of B/Ag(FAl) is changed to 3 : 1 or 1 : 1, the respective coordination compounds [Ag(η(2)‐B)(3)][FAl] (3) and [Ag(2)(η(2) : η(2)‐B)(2)][FAl](2) (4) are accessible. The coordination modes of the cyclo‐As(5) units in 1, 3 and 4 are all different, reflecting the adaptive coordination behavior of B towards Ag(I) ions. The optimized geometries in the gas phase of 1–4 are determined by DFT calculations to support the bonding situation observed in their solid‐state structures.