Electronic Interactions between Ferrocenyl Units Facilitated by the Cobalt Bis(dicarbollide) Anion Linker: An Experimental and DFT Study

Kothanda Rama Pichaandi, Lakshmi Nilakantan, Alexander V. Safronov, Yulia V. Sevryugina, Satish S. Jalisatgi, M. Frederick Hawthorne

Index: 10.1002/ejic.201701019

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Abstract

The electronic interaction between two terminal ferrocenyl units connected by the cobalt bis(dicarbollide) anion linker was investigated. The bis(ferrocenylethynyl)cobalt bis(dicarbollide) anion (3) linking the two ferrocenyl units with the cobalt bis(dicarbollide) anion was synthesized by the reaction of a zinc derivative of ethynylferrocene with the diiodocobalt bis(dicarbollide) anion using Pd0 catalyst in 75 % yield. Complex 3 was unambiguously characterized by NMR and IR spectroscopy, mass spectrometry, and single-crystal X-ray crystallography. The X-ray structure of 3 reveals that the two ferrocenyl units are perpendicular to each other with a total distance of 1.86 nm between the two Fe metal centers. The cyclic voltammogram of 3 shows a single oxidation potential corresponding to the two ferrocenyl units. Time-dependent density functional theory (TD-DFT) studies on complex 3 in tandem with UV/Vis spectroscopic analysis indicate the dominance of the dicarbollide moiety in the LUMOs, and HOMOLUMO transitions at 435 nm illustrate the charge transfer from the two ferrocenyl units to the cobalt bis(dicarbollide) linker. The electronic interaction between two terminal ferrocenyl units connected by the cobalt bis(dicarbollide) anion was investigated by cyclic voltammetry, UV/Vis spectroscopy, and TD-DFT calculations.