Synthesis and characterisation of water soluble ferrocenes: Molecular tuning of redox potentials

Nottingham Trent University, Nottigham, England, United Kingdom
Journal of Organometallic Chemistry (Impact Factor: 2.17). 11/2007; 692(23):5173-5182. DOI: 10.1016/j.jorganchem.2007.07.048


A range of novel water-soluble alkylated ferrocene sulfonate compounds are reported. Mono- and di-sulfonation on a series of alkyl ferrocenes produced 1,1′-dimethyl ferrocene sulfonate, 1,1′-dimethyl ferrocene disulfonate, 1,1′-diethyl ferrocene sulfonate, 1,1′-diethyl ferrocene disulfonate, t-butyl ferrocene sulfonate, t-butyl ferrocene disulfonate, ethyl ferrocene sulfonate, ethyl ferrocene disulfonate, n-butyl ferrocene sulfonate and n-butyl ferrocene disulfonate. All compounds were characterized by NMR spectroscopy, UV/Vis spectroscopy and electrochemical analysis. 1H and 13C NMR studies have revealed the formation of several isomers with sulfonation occurring on positions α and β to the alkyl substituent or on the unsubstituted cyclopentadienyl ring. Variation of the alkyl group allowed the isomeric pattern to be tuned such that the final products followed either electronic or steric control. Cyclic voltammetry of the resulting products showed that the redox potential of the iron centre can be easily manipulated by changing the substituents on the cyclopentadienyl rings. This result has significant implications in the future development of homogenous redox mediators for sensing applications.

11 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: The syntheses and characterization of two ferrocene oils, 4-octyloxy-2-{5-[1,1,3,3-tetramethyl-3-(11-oxo-11-ferrocenyl-undecyl)-disiloxanyl]-pentyloxy}-benzoic acid 4′-undecyloxy-biphenyl-4-yl ester, Fc1SiM and an octakis(ferrocene) species, Fc8Si8M′ are reported, and their biphasic aqueous voltammetry contrasted. Surprisingly, both hydrophobic species undergo single-wave electrochemical dissolution. This can be advantageous to electroanalytical applications.
    Electrochemistry Communications 11/2008; 10(11):1720-1723. DOI:10.1016/j.elecom.2008.08.046 · 4.85 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new and facile method is presented for the synthesis of zirconocene carboxylate compounds, in which zirconocene dichloride (Cp2ZrCl2) is dissolved in 1 M aqueous HCl solution and the requisite ligand is dissolved in an organic solvent. Five such compounds [Cp2ZrCl(μ2-O′,O′′C-C6H5)] (1), [Cp2ZrCl(μ2-O′,O′′C-C6H3Cl2)] (2), [Cp2Zr(μ2-O′,O′′C-C6H3(OH)Cl)2] (3), [Cp2Zr(μ2-O′,O′′C-C6H3(OH)(NO2))2] (4), and [Cp2Zr(μ2-O′,O′′C-C6H(OH)Cl3)2] (5) have been obtained by this method. The effect of pH on the stability of Cp2ZrCl2 in 1 M HCl solution has been investigated by UV/vis spectrophotometry and 1H NMR spectrometry. The results showed that the aqueous Cp2ZrCl2 solutions became less stable with increasing pH, liberating cyclopentadiene. Accordingly, at higher pH (∼7), two trinuclear zirconium monocyclopentadienyl compounds, [(CpZr)3(μ2-O′,O′′C-C6H3Cl2)3(μ3-OH)(μ2-OH)3](Cl2C6H3COO)2 (6) and [(CpZr)3(μ2-O′,O′′C-C6H4Cl)3(μ3-OH)(μ2-OH)3]Cl2·CH2Cl2 (7), were obtained. All compounds 1–7 have been characterized by FT-IR, 1H NMR spectra and elemental analysis. In all of the compounds, the aromatic acid acts as a bidentate ligand in coordinating to the zirconium; both chelating and bridging modes are observed. X-ray crystallographic studies on 1, 6, and 7 have revealed that the geometries at zirconium are distorted octahedral in 6 and 7, and distorted trigonal-bipyramidal in 1.
    Journal of Organometallic Chemistry 10/2009; 694(21):3444–3451. DOI:10.1016/j.jorganchem.2009.06.032 · 2.17 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A comparison of the electrochemical properties of a series of dinuclear complexes [M(2)(L)(RCO(2))(2)](+) with M = Mn or Co, L = 2,6-bis(N,N-bis-(2-pyridylmethyl)-sulfonamido)-4-methylphenolato (bpsmp(-)) or 2,6-bis(N,N-bis(2-pyridylmethyl)aminomethyl)-4-tert-butylphenolato (bpbp(-)) and R = H, CH(3), CF(3) or 3,4-dimethoxybenzoate demonstrates: (i) The electron-withdrawing sulfonyl groups in the backbone of bpsmp(-) stabilize the [M(2)(bpsmp)(RCO(2))(2)](+) complexes in their M(II)(2) oxidation state compared to their [M(2)(bpbp)(RCO(2))(2)](+) analogues. Manganese complexes are stabilised by approximately 550 mV and cobalt complexes by 650 mV. (ii) The auxiliary bridging carboxylato ligands further attenuate the metal-based redox chemistry. Substitution of two acetato for two trifluoroacetato ligands shifts redox couples by 300-400 mV. Within the working potential window, reversible or quasi-reversible M(II)M(III)↔ M(II)(2) processes range from 0.31 to 1.41 V for the [Co(2)(L)(RCO(2))(2)](+/2+) complexes and from 0.54 to 1.41 V for the [Mn(2)(L)(RCO(2))(2)](+/2+) complexes versus Ag/AgCl for E(M(II)M(III)/M(II)(2)). The extreme limits are defined by the complexes [M(2)(bpbp)(CH(3)CO(2))(2)](+) and [M(2)(bpsmp)(CF(3)CO(2))(2)](+) for both metal ions. Thus, tuning the ligand field in these dinuclear complexes makes possible a range of around 0.9 V and 1.49 V for the one-electron E(M(II)M(III)/M(II)(2)) couple of the Mn and Co complexes, respectively. The second one-electron process, M(II)M(III)↔ M(III)(2) was also observed in some cases. The lowest potential recorded for the E°(M(III)(2)/M(II)M(III)) couple was 0.63 V for [Co(2)(bpbp)(CH(3)CO(2))(2)](2+) and the highest measurable potential was 2.23 V versus Ag/AgCl for [Co(2)(bpsmp)(CF(3)CO(2))(2)](2+).
    Dalton Transactions 02/2011; 40(13):3336-45. DOI:10.1039/c0dt01552k · 4.20 Impact Factor
Show more