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. Zwitterionic molecular switches: A neutral mixed‐valence compound has been synthesized and characterized. Spectroscopic data, in conjunction with TD‐DFT calculations, indicate a bridge‐mediated charge transfer that allows for an all‐neutral null state vital to QCA molecular switch applications.