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Tetrakis(ferrocenecarbonitrile) Copper(I) Complexes
Author(s) -
Strehler Frank,
Hildebrandt Alexander,
Korb Marcus,
Lang Heinrich
Publication year - 2013
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201300133
Subject(s) - homoleptic , copper , chemistry , crystallography , electrochemistry , redox , ligand (biochemistry) , metal , electron transfer , transition metal , absorption spectroscopy , inorganic chemistry , electrode , biochemistry , physics , receptor , organic chemistry , quantum mechanics , catalysis
The homoleptic tetrakis(ferrocenecarbonitrile) copper(I) complexes [Cu(N≡CFc) 4 ] A [ A = BF 4 ( 3a ), A = SO 3 CF 3 ( 3b )] were succefully prepared by treatment of copper with the copper(II) salt [Cu A 2 ] · x H 2 O [ A = BF 4 , x = 5 ( 1a ); A = SO 3 CF 3 , x = 0 ( 1b )] in presence of cyanoferrocene ( 2 ). For 3a the tetrahedral arrangement of the four ferrocenecarbonitrile ligands at the copper atom was proven by single X‐ray diffraction studies. The FcC≡N units are weakly bonded to copper, which is reflected by a complete ligand exchange upon addition of MeC≡N forming [Cu(N≡CMe) 4 ]BF 4 ( 4 ). Electrochemical measurements of 3a revealed that all four ferrocenyl units are oxidized in a close potential range and the individual processes are not resolved in the cylic voltammogram. Due to the decrease of electron density at the ferrocenyl termini, the redox event is merely shifted to 456 mV (for comparison, free 2 has E °′ = 436 mV). For 3a intervalence charge transfer (IVCT) absorption between Fe II /Fe III and/or Cu I /Fe III could not be observed in the in situ UV/Vis/NIR spectra in any oxidation state. This alluded that no electronic interaction between the Fc/Fc + termini over the –C≡N–Cu I –N≡C– connectivities takes place. Nevertheless, upon oxidation a ligand‐to‐metal charge transfer (LMCT) band of the ferrocenium groups at 643 nm is visuable accompanied with a shift in the d‐d transition absorptions of the central iron atoms.