Tetrakis(ferrocenecarbonitrile) Copper(I) Complexes

Abstract

The homoleptic tetrakis(ferrocenecarbonitrile) copper(I) complexes [Cu(N≡CFc)4]A [A = BF4 (3a), A = SO3CF3 (3b)] were succefully prepared by treatment of copper with the copper(II) salt [CuA2]·xH2O [A = BF4, x = 5 (1a); A = SO3CF3, 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]BF4 (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 FeII/FeIII and/or CuI/FeIII 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–CuI–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.

Crystal structure of ruthenocenecarbonitrile

“…A synthesis for ferrocenecarbonitrile has already been described in 1957 (Graham et al, 1957); however, only one example of an application in electrochemical studies has been described by Dowling et al (1981). This prompted us to synthesize ferrocenecarbonitrile transition metal complexes to investigate the electronic properties of the -C N-M-N Cbridging units (Strehler et al 2013(Strehler et al , 2014. In a continuation of this work, we present herein the synthesis and crystal structure of the related ruthenocenecarbonitrile, (I).…”

RuII and RuIII Chloronitrile Complexes: Synthesis, Reaction Chemistry, Solid State Structure, and (Spectro)Electrochemical Behavior

“…A three electrode cell, which utilized a Pt auxiliary electrode, a glassy carbon working electrode (surface area 0.031 cmò) and an Ag/Ag + (0.01 mol · L –1 AgNO 3 ) reference electrode was used as described in reference. [ 36,41–50 ] Successive experiments under the same experimental conditions showed that all formal potentials were reproducible within ±5 mV. Experimental potentials were referenced against an Ag/Ag + reference electrode, but results are presented referenced against ferrocene [FcH/FcH + couple = 220 mV vs. Ag/Ag + , Δ E p = 61 mV; FcH = Fe(η 5 ‐C 5 H 5 ) 2 ] as an internal standard.…”

Crystal structure of paddle-wheel sandwich-type [Cu2{(CH3)2CO}{μ-Fe(η5-C5H4C[triple-bond]N)2}3](BF4)2·(CH3)2CO

“…In contrast, a weak electron transfer by generation of the mixedvalence species [Ru(N CFc)(NH 3 ) 5 ] 3+ [Fc = Fe( 5 -C 5 H 4 )( 5 -C 5 H 5 )] has been described (Dowling et al, 1981). We recently reported on the synthesis, characterization and electrochemical properties of platinum and copper complexes containing a -C N-M-N C-(M = Cu or Pt) bridging unit between two redox-active ferrocenyl moieties (Strehler et al, 2013(Strehler et al, , 2014 to achieve a direct comparison with the -C C-M-C C-building blocks. In addition, the coordination of ferrocene-1,1 0 -dicarbonitrile towards PtCl 2 resulted in an oligomeric complex (Strehler et al, 2014).…”