Controlling the Reactivity of Ferrocenyl Carbocations: Routes to Enantiomerically Pure Chlorophosphites and Solid‐State Characterization of a Benzopentalene Dimer

A range of enantiopure ferrocenyl diols possessing a variety of electron‐withdrawing groups at the carbinol centre was investigated in the reaction with phosphorus trichloride. Subtle changes in the electronic properties of these groups led, after reaction with phosphorus trichloride, to distinctly different products: α‐substituted ferrocenes, (bis)phosphinic dichlorides, benzopentalene dimers or chlorophosphites. A mechanistic rationale was developed based upon the observed α‐ferrocenyl carbocation behaviour to account for the formation of such diverse products. Two benzopentalene dimers were isolated and successfully characterized by X‐ray crystallography, representing the first examples of such compounds in the solid‐state. The synthesis and characterization of an enantiopure ferrocenophane‐phosphoramidite‐gold(I) complex is also described.