(Electrochemical) Properties and Computational Investigations of Ferrocenyl-substituted Fe33-PFc)2(CO)9 and Co44-PFc)2(CO)9 Clusters and Their Reduced Species

Marcus Korb, Xianming Liu, Sebastian Walz, Marco Rosenkranz, Evgenia Dmitrieva, Alexey A. Popov, Heinrich Lang

Research output: Contribution to journalArticle

Abstract

The formation of ferrocenyl-functionalized iron and cobalt carbonyl clusters is reported, based on a reaction of FcPCl2 (3) (Fc = Fe(η5-C5H5)(η5-C5H4)) with Fe2(CO)9 and Co2(CO)8, respectively. Therein, nido-Fe3(CO)93-PFc)2 (4) and nido-Co4(CO)103-PFc)2 (5) clusters were obtained as the first diferrocenyl-substituted carbonyl clusters with a symmetrical cluster core. Cluster 4 shows two reversible one-electron processes within the anodic region, based on Fc/Fc+ redox events, as well as two processes in the cathodic region. In situ IR and electron paramagnetic resonance (EPR) measurements of all electronic states confirmed an Fc-based oxidation and a core-based reduction. On the basis of the results of a single-crystal X-ray analysis of structures of 4 and 5, computational studies of the highest occupied molecular orbital-lowest unoccupied molecular orbital energies, the spin density, quantum theory of atom-in-molecule delocalization indices, and the atomic charges were performed to explain the experimental results. The latter revealed a reorganization of the cluster core upon reduction and the existence of weak P···P interactions in 4 and 5. Ferrocenyl-related redox processes, occurring reversibly in case of 4, were absent for 5, due to a different distribution of the HOMO energies. EPR measurements furthermore confirmed the core-based radical anion and the formation of a decomposition product at potentials lower than [M]2- (M = Fe, Co).

Original languageEnglish
Pages (from-to)6147-6160
Number of pages14
JournalInorganic Chemistry
Volume59
Issue number9
DOIs
Publication statusPublished - 4 May 2020

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