Isomeric commo-Ferracarboranes: meso-, dd/ll-[PPh3R][commo-Fe(2,4-closo-C2B8H10)2] and Their Bimetal Ferra–Copper Zwitterion Derivatives

5 years ago

Isomeric commo-Ferracarboranes: meso-, dd/ll-[PPh3R][commo-Fe(2,4-closo-C2B8H10)2] and Their Bimetal Ferra–Copper Zwitterion Derivatives

Igor T. Chizhevsky, Fedor M. Dolgushin, Dmitrii I. D'yachihin, Alexander F. Smol'yakov, Svetlana M. Peregudova, Vadim V. Minin, Anastasia I. Silivonenko, Alexander Yu. Kostyukovich, Elena V. Balagurova

The reaction of [Na][C2B8H11] with anhydrous FeCl2 in THF affords a mixture of dd/ll and meso isomers of anionic paramagnetic commo-ferracarborane [Ph3PR][commo-1,1′-Fe(closo-2,4-C2B8H10)2] (meso, R = Me: 1a; meso, Et: 1b; dd/ll, R = Me: 2a; dd/ll, R = Et: 2b) with unusual closo geometry. Both dd/ll and meso isomers were successfully isolated and their structures were determined using single-crystal X-ray diffraction studies. Their paramagnetic properties were confirmed with EPR spectra and their oxidative–reductive properties were investigated using cyclic voltammetry. It was shown that facile dd/ll meso and meso dd/ll transformations, leading to equilibrium in CH2Cl2 solution, occur. Quantum-chemical calculations of the isomer-to-isomer transformations were performed. Ferra–copper zwitterionic complexes [3,3′,6,7′-exo-{Ph3PCu}-3,3′,6,7′-(µ-H)4-commo-1,1′-Fe(2,4-C2B8H8)2] and [3,3′,6,6′-exo-{Ph3PCu}-3,3′,6,6′-(µ-H)4-commo-1,1′-Fe(2,4-C2B8H8)2] were synthesized and their structures were determined by single-crystal X-ray diffraction studies. The dd/ll and meso isomers of commo-ferracarborane [Ph3PR][commo-1,1′-Fe(closo-2,4-C2B8H10)2], with closo geometry, were obtained and their structures determined. Facile dd/ll meso and meso dd/ll transformations occur in solution and DFT calculations of the interconversions were performed. Ferra–copper zwitterionic complexes of each isomer were synthesized and their structures determined.

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DOI: 10.1002/ejic.201700571