Citation
Hamilton, Walter Clark (1954) I. The Crystal Structure of Dimethyl Phosphino-Borine Trimer. II. The Method of Least Squares in Electron Diffraction. III. Some Structural Studies by the Electron Diffraction by Gas Molecules. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/FCYP-NV05. https://resolver.caltech.edu/CaltechETD:etd-12152003-090535
Abstract
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The crystal structure of dimethyl phosphino-borine trimer, [(CH[subscript 3][subscript 2]PBH[subscript 2][subscript 3], has been determined by analysis of its x-ray diffraction maxima. Use was made of a three-dimensional Patterson function, least squares on the structure factors, and a three-dimensional electron-density difference map. The space group is P[subscript nma]; the unit cell constants are a = 11.16 [angstroms], b = 13.16 [angstroms], and c = 10.53 [angstroms]. There are four molecules per unit cell. The molecule has a cyclohexane-like ring of alternating phosphorus and boron atoms, with two methyl groups attached to each phosphorus atom. It has a plane of symmetry, and the environment of each phosphorus atom is C[subscript 2v]. The following average structural parameters were found: [...].ome attention is given to the determination of temperature factors from the difference map and to fitting of atomic form factors by Gaussians. The R factor for the final structure is 0.169. The advantages of the method of least squares, as contrasted to the usual correlation treatment, in electron diffraction investigations of molecular structure are outlined. Special attention is given to visual data and to the weighting of observations, including remarks on the use of a non-diagonal weight matrix and the derivation of weights from the goodness of fit, and to obtaining reliable estimates of error, and of error correlation, for the parameters. The method of least squares has been applied to electron diffraction photographs of bicycloheptadiene, C[subscript 7]H[subscript 8], and bicyclo-octane, C[subscript 8]H[subscript 14]. In the case of bicyeloheptadiene, a simple valence-force potential function adequately explains the values found for the structural-parameters. The structure of difluoromethane has been reinvestigated by electron diffraction.
Item Type: | Thesis (Dissertation (Ph.D.)) |
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Subject Keywords: | (Chemistry and Mathematics) |
Degree Grantor: | California Institute of Technology |
Division: | Chemistry and Chemical Engineering |
Major Option: | Chemistry |
Minor Option: | Mathematics |
Thesis Availability: | Public (worldwide access) |
Research Advisor(s): |
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Thesis Committee: |
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Defense Date: | 1 January 1954 |
Record Number: | CaltechETD:etd-12152003-090535 |
Persistent URL: | https://resolver.caltech.edu/CaltechETD:etd-12152003-090535 |
DOI: | 10.7907/FCYP-NV05 |
Default Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. |
ID Code: | 5000 |
Collection: | CaltechTHESIS |
Deposited By: | Imported from ETD-db |
Deposited On: | 17 Dec 2003 |
Last Modified: | 08 Jun 2023 22:23 |
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