Oxidation Chemistry of Inorganic Benzene Complexes

The oxidation of the 28 VE cyclo‐E₆ triple‐decker complexes (Cp^RMo)₂(μ,η⁶:η⁶‐E₆)] (E=P, Cp^R=Cp( 2 a ), Cp*( 2 b ), Cp^Bn( 2 c )=C₅(CH₂Ph)₅; E=As, Cp^R=Cp*( 3 )) by Cu⁺ or Ag⁺ leads to cationic 27 VE complexes that retain their general triple‐decker geometry in the solid state. The obtained products have been characterized by cyclic voltammetry (CV), EPR, Evans NMR, multinuclear NMR spectroscopy, MS, and structural analysis by single‐crystal X‐ray diffraction. The cyclo‐E₆ middle decks of the oxidized complexes are distorted to a quinoid ( 2 a ) or bisallylic ( 2 b , 2 c , 3 ) geometry. DFT calculations of 2 a , 2 b , and 3 persistently result in the bisallylic distortion as the minimum geometry and show that the oxidation leads to a depopulation of the σ‐system of the cyclo‐E₆ ligands in 2 a – 3 . Among the starting complexes, 2 c is reported for the first time including its preparation and full characterization.