Coordination Behavior of [Cp″₂Zr(µ^1:1-As₄)] towards Lewis Acids

The functionalization of the arsenic transfer reagent [Cp″₂Zr(η^1:1-As₄)] (1) focuses on modifying its properties and enabling a broader scope of reactivity. The coordination behavior of 1 towards different Lewis-acidic transition metal complexes and main group compounds is investigated by experimental and computational studies. Depending on the steric requirements of the Lewis acids and the reaction temperature, a variety of new complexes with different coordination modes and coordination numbers could be synthesized. Depending on the Lewis acid (LA) used, a mono-substitution in [Cp″₂Zr(µ,η^1:1:1:1-As₄)(LA)] (LA = Fe(CO)₄ (4); B(C₆F₅)₃ (7)) and [Cp″₂Zr(µ,η^3:1:1-As₄)(Fe(CO)₃)] (5) or a di-substitution [Cp″₂Zr(µ₃,η^1:1:1:1-As₄)(LA)₂] (LA = W(CO)₅ (2); CpMn(CO)₂ (3); AlR₃ (6, R = Me, Et, ⁱBu)) are monitored. In contrast to other coordination products, 5 shows an η³ coordination in which the butterfly As₄ ligand is rearranged to a cyclo-As₄ ligand. The reported complexes are rationalized in terms of inverse coordination.