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Published on: July 27, 2022
Structural diversity of mixed polypnictogen complexes: dicationic E2E'2 (E ≠ E' = P, As, Sb, Bi) chains, cycles and
Luis Dütsch1, Christoph Riesinger1, Gábor Balázs1
1Department of Inorganic Chemistry, University of Regensburg D-93040 Regensburg Germany manfred.scheer@chemie.uni-regensburg.de.
Abstract:
The reactivity of the tetrahedral dipnictogen complexes [{CpMo(CO)2}2(μ,η2:η2-EE')] (E, E' = P, As, Sb, Bi; "Mo") towards different one-electron oxidation agents is reported. Oxidation with [Thia][TEF] (Thia+ = C12H8S2 +; TEF- = Al{OC(CF3)3}4 -) leads to the selective formation of the radical monocations [Mo2EE']˙+, which immediately dimerize to the unprecedented dicationic E2E'2 ligand complexes [{CpMo(CO)2}4(μ4,η2:η2:η2:η2-E'EEE')]2+ via E-E bond formation. Single crystal X-ray diffraction revealed that, in the case of Mo and Mo, P-P bond formation occurs yielding zigzag E2P2 (E = As (1), Sb (2)) chains, whereas Mo forms a Sb2Bi2 (5) cage, Mo an unprecedented As2Sb2 unit representing an intermediate stage between a chain- and a cage-type structure, and Mo a novel planar As2Bi2 (4a) cycle. Therefore, 1-5 bear the first substituent-free, dicationic hetero-E4 ligands, stabilized by transition metal fragments. Furthermore, in the case of Mo, the exchange of the counterion causes changes in the molecular structure yielding an unusual, cyclic As2Sb2 ligand. The experimental results are corroborated by DFT calculations.
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