Jump to main content
Jump to site search

Issue 17, 2018
Previous Article Next Article

Electron-density distributions in selected ferrocenyl-pyrazolyl late transition-metal complexes

Author affiliations

Abstract

57Fe Mössbauer spectroscopy has been used to study electronic dispersions in complexes of Fe, Co, Ni and Pd anchored onto 3-ferrocenyl-5-methylpyrazolylmethylenepyridine and 3-ferrocenylpyrazolylmethylenepyridine ligands. Mössbauer spectroscopy shows that pyrazolyl-derivatizing of ferrocene increases the electron-density at the Fe-centre as well as facilitating the Fe to cyclopentadienyl ring back-donation of electron-density. The coordination of the ferrocenyl-pyrazolyl ligand to transition metals such as Fe, Co, Ni and Pd reduces the electron-density at the Fe-centre of the ferrocenyl moiety while increasing the electron-density at the coordinated metal centre, especially in the Fe complexes. The electron-density change at the coordination metal centre is inversely proportional to the electronegativity of the halide substituent. Furthermore, the type of substituent (Me or H) at position 5 on the pyrazolyl moiety has an influence on the electron density at the ferrocenyl-Fe and the coordinated metal centre. The methyl group as a substituent reduces the π-acceptor ability of the pyrazolyl and therefore increases the electron-density at the ferrocenyl-Fe centre. However, when the substituent is hydrogen, the electron-density at the coordination metal centre increases. Similarly, for other metals (i.e., Co, Ni and Pd) the electron density at the ferrocenyl-Fe is also significantly reduced upon coordination of the ligand to the metal. Additionally, Mössbauer experiments reveal a trivalent Fe species in the synthesized complexes which is not discerned by X-ray and elemental analysis. The species has been identified as the oxidative product [Fe(III)X4] where X = Cl or Br. The study also highlights and cautions on the possibility of photo-oxidation processes involving both ferrocene and the coordinating Fe-halides under standard lighting conditions with possible contributions from aerated solvents.

Graphical abstract: Electron-density distributions in selected ferrocenyl-pyrazolyl late transition-metal complexes

Back to tab navigation

Supplementary files

Publication details

The article was received on 19 Feb 2018, accepted on 27 Mar 2018 and first published on 27 Mar 2018


Article type: Paper
DOI: 10.1039/C8CP01135D
Citation: Phys. Chem. Chem. Phys., 2018,20, 11682-11691
  •   Request permissions

    Electron-density distributions in selected ferrocenyl-pyrazolyl late transition-metal complexes

    M. A. Peck, G. R. Hearne, C. Obuah and J. Darkwa, Phys. Chem. Chem. Phys., 2018, 20, 11682
    DOI: 10.1039/C8CP01135D

Search articles by author

Spotlight

Advertisements