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I. The heptacyanomolybdate (III) ion : spectroscopic and magnetic properties and chemical reactivity. II. Spectroscopic and magnetic studies of monomeric and dimeric d^5 systems. III. Spectroscopic and magnetic studies of polymeric oxo- and hydroxobridged systems

Citation

Rossman, George Robert (1971) I. The heptacyanomolybdate (III) ion : spectroscopic and magnetic properties and chemical reactivity. II. Spectroscopic and magnetic studies of monomeric and dimeric d^5 systems. III. Spectroscopic and magnetic studies of polymeric oxo- and hydroxobridged systems. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/JZTQ-Q938. https://resolver.caltech.edu/CaltechTHESIS:12202016-092448657

Abstract

Heptacyanomolybdate(III), isolated as the potassium salt, K4Mo(CN)7 · 2H2O has been studied by infrared, raman, ESR, magnetic susceptibility, optical spectral, and x-ray techniques. Solutions of the ion have been identified as having a seven-coordinate pentagonal bipyramidal structure, while the structure in the solid potassium salt has been proposed to be a capped trigonal prism. The anhydrous potassium salt, K4Mo(CN)7, and the hydrated cesium salt, Cs4Mo(CN)7 · xH2O also assume the pentagonal bi pyramidal geometry. The molecule is chemically reactive, combining readily in solution with oxygen to form [Mo(CN)7OH2]4- and with halogens to form products which when isolated are waxy and presumably polymeric.

Optical spectra have been obtained for four-, five-, six-, and seven-coordinate manganese(II) and iron(III) compounds. These are used as a basis of comparison for interpretation of the detailed optical and magnetic data obtained on the oxobridged iron(III) dimer enH2[(FeHEDT A)2O] · 6H2O.

The occurrence of simultaneous pair electronic excitations in the dimer is described, and evaluation of the relative merits of the spin-coupling and molecular orbital models for oxobridged dimers is presented. A dihydroxobridged ferric dimer is described as well as a series of dialkoxobridged iron(m) and aluminum dimers derived from metal acetylacetonate and dipivaloylmetane complexes. The extent of antiferromagnetic coupling between the two iron atoms in the dihydroxo- and the dialkoxobridged iron dimers has been found to be nearly identical through variable temperature magnetic susceptibility studies. The magnetic and infrared studies are extended to include a variety of metal oxides, oxy-hydroxides, and natural and synthetic minerals which have various forms of oxo- and hydroxobridging. The OH infrared bands are identified and in some instances, the LN2 temperature positions of the band are compared to the room temperature position. Ferritin models and ferritin micelles are compared to these iron polymers, and the similarity of the infrared spectrum of ferric hydroxide to ferritin micelles is discussed.

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:26 February 1971
Funders:
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
Record Number:CaltechTHESIS:12202016-092448657
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:12202016-092448657
DOI:10.7907/JZTQ-Q938
ORCID:
AuthorORCID
Rossman, George Robert0000-0002-4571-6884
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9999
Collection:CaltechTHESIS
Deposited By: Benjamin Perez
Deposited On:20 Dec 2016 19:17
Last Modified:21 Dec 2019 02:12

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