Synthesis of a Neutral Mixed‐Valence Diferrocenyl Carborane for Molecular Quantum‐Dot Cellular Automata Applications

The preparation of 7-Fc+-8-Fc-7,8-nido-[C2B9H10]− (Fc+FcC2B9−) demonstrates the successful incorporation of a carborane cage as an internal counteranion bridging between ferrocene and ferrocenium units. This neutral mixed-valence FeII/FeIII complex overcomes the proximal electronic bias imposed by external counterions, a practical limitation in the use of molecular switches. A combination of UV/Vis-NIR spectroscopic and TD-DFT computational studies indicate that electron transfer within Fc+FcC2B9− is achieved through a bridge-mediated mechanism. This electronic framework therefore provides the possibility of an all-neutral null state, a key requirement for the implementation of quantum-dot cellular automata (QCA) molecular computing. The adhesion, ordering, and characterization of Fc+FcC2B9− on Au(111) has been observed by scanning tunneling microscopy.