Accession Number : ADA192995

Title :   Intervalence Electron Transfer in Bicobaltocene Cations: Comparison with Biferrocenes.

Descriptive Note : Technical rept.,

Corporate Author : PURDUE UNIV LAFAYETTE IN DEPT OF CHEMISTRY

Personal Author(s) : McManis, George E ; Nielson, Roger M ; Weaver, Michael J

PDF Url : ADA192995

Report Date : 17 Feb 1988

Pagination or Media Count : 15

Abstract : The near-infrared absorption parameters for bicobaltocene monocation, (Cp2Co)2+, evaluated in several solvents, are compared with corresponding data for biferrocene cation, (Cp2Fe)2+, in order to ascertain the consequence of metal substitution upon the degree of redox-site electronic coupling. From the markedly (ca. 5 fold) larger intervalence band intensities, narrower bandwidths, and milder solvent dependence of the band energy observed for the former system, the degree of Co(III)-Co(II) electronic coupling is deduced to be substantially greater than for Fe(III)-Fe(II). A similar conclusion is reached from a comparison of near-infrared spectra for bis(fulvalene)-dicobalt and -diiron monocations. These differences are also reflected in more negative comproportionation free energies for the cobalt mixed-valence analogs, as derived from electrochemical data. These findings are consistent with orbital symmetry considerations, since electron transfer for the Co(III)-Co(II) system is expected to involve a ligand-centered 4e1g orbital, as compared with strongly metal-localized 4e2 or 8a1g orbitals that are apparently utilized in the Fe(III)-Fe(II) metallocene case. Keywords: Mixed valence compounds, Donor acceptor orbital overlap, Electronic coupling, Biferrocene, Bicobaltocene.

Descriptors :   *CATIONS, *ELECTRON TRANSFER, *COBALT COMPOUNDS, *ORGANOMETALLIC COMPOUNDS, ABSORPTION, BANDWIDTH, CATIONS, COMPARISON, COUPLING(INTERACTION), ELECTROCHEMISTRY, ELECTRON ACCEPTORS, ELECTRON TRANSFER, ENERGY, ENERGY BANDS, METALS, MIXING, NEAR INFRARED RADIATION, OVERLAP, PARAMETERS, SOLVENTS, SUBSTITUTES, SYMMETRY, VALENCE, ABSORPTION SPECTRA, MOLECULAR ORBITALS, FERROCENES

Subject Categories : Organic Chemistry
      Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE