Evidence of Next-Nearest-Neighbor Electronic Coupling in a Series of Cyano-Bridged trans-Fe(II)-Pt(IV)-M(II) (M=Fe, Ru) Asymmetric Trimers
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This work describes the synthesis and characterization of a series of cyano-bridged dimers and trimers of the M-Pt (M = Fe, Ru) and M-Pt-M’ (M/M’ = Fe, Ru) type and their electronic properties in the UV-Visible spectrum. These compounds were synthesized and their electronic properties were examined in the UV-Visible region in order to gain understanding of weakly-coupled metal-to-metal charge transfer (MMCT) in Robin and Day Class II systems. From a theoretical point of view, the electronic properties of mixed valence (MV) compounds are based on four factors: (1) the symmetry of a given species, (2) the effects of spin-orbit coupling on the electron-transfer processes, (3) the effect of nearest-neighbor (NN) electronic coupling, and (4) the effect of next-nearest-neighbor (NNN) electronic coupling. We have observed remote (NNN) electronic coupling between the Fe(II) and Ru(II) metal center in the asymmetric [(CN)5Fe(μ-CN)Pt(NH3)4(μ-CN)Ru(CN)5]4- MV species. In contrast, the symmetric [(CN)5Fe(μ-CN)Pt(NH3)4(μ-CN)Fe(CN)5]4- and [(CN)5Ru(μ-CN)Pt(NH3)4(μ-CN)Ru(CN)5]4- species, the trimers can be treated as two back-to-back donor-acceptor pairs that happen to share a Pt(IV) molecular orbital acceptor. This type of a long-distance electronic communication is important in the design of many different types of chemical systems as diverse as molecules that are useful as solar energy conversion catalysts, molecular electronic devices, and in the understanding of long-range electron transfer in biological systems.
Esposito, Michael C., "Evidence of Next-Nearest-Neighbor Electronic Coupling in a Series of Cyano-Bridged trans-Fe(II)-Pt(IV)-M(II) (M=Fe, Ru) Asymmetric Trimers" (2018). Chemistry Honors Papers. 8.