A Tetrairon Dication Featuring Tetraethynylbenzene Bridging Ligand: a Molecular Prototype of Quantum-Dot Cellular Automata.

the unprecedented tetrairon dication [{Cp*(dppe)FeC identical withC-} 4 -mu-(1,2,4,5-C 6 H 2 )](PF 6 ) 2 ( 1 ) was obtained through a sequence of three reactions from 1,2,4,5-tetraethynylbenzene, Cp*(dppe)FeCl (Cp* = C 5 Me 5 , dppe = 1,2-bis(diphenylphosphino)-ethane), KOBu t , and ferrocenium hexafluorophosphate. The cyclic voltammogram of the target molecule isolated in 77% yield, exhibits four well separated and reversible redox events showing that 1 is thermodynamically stable with respect to disproportionation ( K c > 10 6 ). The tetranuclear dication 1 was characterized by XRD on single crystal, IR and NMR spectroscopies and Mossbauer spectrometry. The experimental data show that 1 behaves as a class II mixed-valence complex with the positive charges preferentially disposed on antipodal positions. This new molecule can be regarded as a potential molecular prototype of quantum-dot cellular automata.