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Electronic Structures of Metallocene Complexes. I. Electronic Structure of Metallocenes. Optical Spectroscopic Study of Metallocene Complexes. II. Magnetic Susceptibility Study of the Ferricenium Ion. III. Synthesis and Characterization of Several Oxidation Products of Ruthenocene

Citation

Sohn, Youn Soo (1970) Electronic Structures of Metallocene Complexes. I. Electronic Structure of Metallocenes. Optical Spectroscopic Study of Metallocene Complexes. II. Magnetic Susceptibility Study of the Ferricenium Ion. III. Synthesis and Characterization of Several Oxidation Products of Ruthenocene. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/pg0q-y417. https://resolver.caltech.edu/CaltechTHESIS:09262017-114444994

Abstract

I. ELECTRONIC STRUCTURE OF METALLOCENES

The electronic absorption spectra of various low-spin d5 and d6 metallocene complexes have been studied in different environments (glasses, KBr pellets, and single crystals) and as a function of temperature. Ferrocene, phenylferrocene, ruthenocene, and cobalticenium ion were selected in the d6 study and several ferricenium, n-butylferricenium, and 1,1' -di-n-butylferricenium salts were examined in the d5 case. The electronic spectra of ferrocene and phenylferrocene single crystals at 4.2°K clearly indicate that the bands at 22,700 cm-1 and 22,400 cm-1, respectively, consist of two electronic transitions each. The corresponding band systems in ruthenocene and cobalticenium ion also exhibit asymmetry at 77 °K. Ligand field theory has been successfully applied to the above d6 metallocenes, utilizing the three observed spin-allowed d-d absorption band positions. Emission of ruthenocene has been observed at 23,300 cm-1 and discussed in conjunction with the reported ferrocene emission. The visible absorption spectra of the various ferricenium complexes show a low-energy charge transfer transition (16,200 cm-1 in the unsubstituted ion). Ring substitution and temperature effects have been used to assign this band to the ligand-to-metal 2E2g2E1u transition. The vibrational structure observed for this band at 77°K appears as a doubled progression of the lowest energy a1g vibration. The doubling has been attributed to splitting of the 2E1u excited state. Detailed assignments of this vibrational structure are given for [Fe(cp)2]PF6 and [Fe(cp)2](CCl3CO2H)3. The intense charge transfer band of ferrocene(~ 50,000 cm-1), as well as the corresponding bands in the other d6 metallocenes, have been assigned as ligand-to-metal transitions. A similar assignment has been proposed for the three strong (f ≈ 0.1) bands observed in the ferricenium ultraviolet absorption spectrum.

II. MAGNETIC SUSCEPTIBILITY STUDY OF THE FERRICENIUM ION

The ground electronic state [2E2g(a1g)2(e2g)3] of the ferricenium ion has been further characterized by a variable-temperature (40-300°K) magnetic susceptibility study of nine ferricenium and two analogous Fe(III) dicarbollide (1,2-B9C2H112- state. Solvent and counter ion effects on the magnetic properties of the ferricenium ion are appreciable.

III. SYNTHESIS AND CHARACTERIZATION OF SEVERAL OXIDATION PRODUCTS OF RUTHENOCENE

Attempts to prepare ruthenicenium salts have resulted in the synthesis and characterization of several interesting ruthenocene derivatives. Contrary to a previous report, electrochemical oxidation of ruthenocene employing a mercury anode yields the mercury-bridged dimer [(cp)2Ru-Hg-Ru(cp)2](ClO4)2. Analytical, infrared, Raman, and electronic absorption spectral data were utilized in assigning the molecular structure. In particular, a Raman band at 110 cm-1 was assigned to the symmetrical Ru-Hg-Ru stretching mode. Preliminary X-ray crystallographic data for the hexafluorophosphate salt, which was obtained by anion exchange, are in agreement with the above dimeric formulation. Chemical oxidation of ruthenocene by iodine and bromine gives [Ru(cp)2I]I3 and [Ru(cp)2Br]Br3, respectively, as indicated by analytical and spectral data.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Gray, Harry B.
Thesis Committee:
  • Unknown, Unknown
Defense Date:7 August 1970
Funders:
Funding AgencyGrant Number
CaltechUNSPECIFIED
NSFUNSPECIFIED
Record Number:CaltechTHESIS:09262017-114444994
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:09262017-114444994
DOI:10.7907/pg0q-y417
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10458
Collection:CaltechTHESIS
Deposited By: Benjamin Perez
Deposited On:26 Sep 2017 22:31
Last Modified:19 Apr 2021 22:30

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