Synthesis of arsenic-rich Asn ligand complexes from yellow arsenic

The reaction of [{eta(5)-Cp''' Co}(2){mu,eta(4:4)-toluene}] with yellow arsenic yields the arsenic-rich As-n ligand complexes [{Cp''' Co(mu,eta(2:2)-As-2)}(2)] (1), [(Cp''' Co)(4)(mu(4),eta(4:4:2:2:1:1)-As-10)] (2) and [(Cp''' Co)(3)(mu(3),eta(4:4:2:1)-As-12)] (3), which were comprehensively characterized. The molecular structure of 1 show a triple-decker complex with two As-2 units forming the middle-deck; compound 2 contains an all-arsenic As-10 analogue of dihydrofulvalene in the molecular structure. The As-12 ligand in 3 represents the largest Asn ligand complex reported so far.