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

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dc.contributor.authorPeck, M.A.
dc.contributor.authorHearne, G.R.
dc.contributor.authorObuah, C.
dc.contributor.authorDarkwa, J.
dc.date.accessioned2019-07-23T12:20:59Z
dc.date.available2019-07-23T12:20:59Z
dc.date.issued2018-03
dc.description.abstract57Fe Mössbauer spectroscopy has been used to study electronic dispersions in complexes of Fe, Co, Ni and Pd anchored on 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 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.en_US
dc.identifier.otherDOI: 10.1039/C8CP01135D
dc.identifier.urihttp://ugspace.ug.edu.gh/handle/123456789/31671
dc.language.isoenen_US
dc.publisherPhysical Chemistry Chemical Physicsen_US
dc.titleElectron-density distributions in selected ferrocenyl-pyrazolyl late transition-metal complexesen_US
dc.typeArticleen_US

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