The Potential of a cyclo-As5 Ligand Complex in Coordination Chemistry

Abstract

The reaction of [Cp*Fe(η5-As5)] (1) with CuI halides leads to the formation of the 1D-polymeric compounds [3(CH3CN)]n (X = Cl (2), Br (3)), [2]n (4) and [3]n (5). The polymers are built up by the π-coordination of the cyclo-As5 ring to (CuX)n moieties forming discrete units, which are additionally linked by weak intermolecular AsCu σ-interactions. Only polymer 4 is an exception revealing a (CuI)n ladder which is alternately coordinated by molecules of 1. In a side arm of polymer 5 a novel η5-coordination of a Cu atom below the cyclo-As5 ring is found, showing an unprecedented heteroleptic triple-decker sandwich complex with a polyarsenic middle-deck. All products are characterised by single crystal X-ray structure analysis. To define the differences in the coordination behaviour of 1 and its phosphorus analogue [Cp*Fe(η5-P5)] (1a), DFT calculations are described.