Redox Chemistry of an End-Deck cyclo-As3 Nickel Complex

The redox chemistry of [Cp‴Ni­(η3-As3)] (A), an end-deck cyclo-As3 complex, is explored in terms of systematically accessing a series of Ni2As3 triple-decker compounds. While oxidation of A affords the cationic complex [{Cp‴Ni}2(μ,η3:3-As3)]­[FAl] (1, [FAl]− = [FAl­{O­(1-C6F5)­C6F10}3]−), reduction of A yields the anionic [K@crypt]­[{Cp‴Ni}2(μ,η3:3-As3)] (2, crypt = [2.2.2]-cryptand). One-electron reduction of 1 and one-electron oxidation of 2 yield the neutral compound [{Cp‴Ni}2(μ,η3:3-As3)] (3), representing the missing link between 1 and 2, which is corroborated electrochemically. The cyclo-As3 ligand in 2 undergoes bond weakening and splitting of one As–As bond upon stepwise oxidation to 3 and 1, finally displaying an allylic As3 ligand. In-depth experimental studies shed light onto the reaction pathway of the oxidation of A, and additional DFT computations give insight into the electronic structure of the obtained complexes.