Versatile Coordination of AgI and CuI Ions towards cyclo-As5 Ligands

Abstract

The reactions of the cyclo-As5 complex [Cp*Fe(η5-As5)] (B) with the AgI and CuI salts of the weakly coordinating anion (WCA) [FAl{OC6F10(C6F5)}3]− ([FAl]−) are studied. These reactions allow the synthesis of the mononuclear complexes [M(η5 : η2-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 AgI cation between two π-coordinating cyclo-As5 ligands, which is absent in 2 pointing to a weak interaction of the Ag center towards the cyclo-As5 ligands in B. When the ratio of B/Ag(FAl) is changed to 3 : 1 or 1 : 1, the respective coordination compounds [Ag(η2-B)3][FAl] (3) and [Ag2(η2 : η2-B)2][FAl]2 (4) are accessible. The coordination modes of the cyclo-As5 units in 1, 3 and 4 are all different, reflecting the adaptive coordination behavior of B towards AgI 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.