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I. The Crystal Structure of Potassium Bis-(Tricyanovinyl) Amine. II. Nuclear Magnetic Resonance Studies of Alkali Halide Solutions. III. Elucidation of the Intramolecular Hydrogen Bond in Acetylacetone by the Deuterium Isotope Effect on the Chemical Shift of the Bridge Hydrogen

Citation

Lin, Leroy Chi-tsun (1968) I. The Crystal Structure of Potassium Bis-(Tricyanovinyl) Amine. II. Nuclear Magnetic Resonance Studies of Alkali Halide Solutions. III. Elucidation of the Intramolecular Hydrogen Bond in Acetylacetone by the Deuterium Isotope Effect on the Chemical Shift of the Bridge Hydrogen. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/125N-CX62. https://resolver.caltech.edu/CaltechTHESIS:12212015-083027456

Abstract

Part I

Potassium bis-(tricyanovinyl) amine, K+N[C(CN)=C(CN)2]2-, crystallizes in the monoclinic system with the space group Cc and lattice constants, a = 13.346 ± 0.003 Å, c = 8.992 ± 0.003 Å, B = 114.42 ± 0.02°, and Z = 4. Three dimensional intensity data were collected by layers perpendicular to b* and c* axes. The crystal structure was refined by the least squares method with anisotropic temperature factor to an R value of 0.064.

The average carbon-carbon and carbon-nitrogen bond distances in –C-CΞN are 1.441 ± 0.016 Å and 1.146 ± 0.014 Å respectively. The bis-(tricyanovinyl) amine anion is approximately planar. The coordination number of the potassium ion is eight with bond distances from 2.890 Å to 3.408 Å. The bond angle C-N-C of the amine nitrogen is 132.4 ± 1.9°. Among six cyano groups in the molecule, two of them are bent by what appear to be significant amounts (5.0° and 7.2°). The remaining four are linear within the experimental error. The bending can probably be explained by molecular packing forces in the crystals.

Part II

The nuclear magnetic resonance of 81Br and 127I in aqueous solutions were studied. The cation-halide ion interactions were studied by studying the effect of the Li+, Na+, K+, Mg++, Cs+ upon the line width of the halide ions. The solvent-halide ion interactions were studied by studying the effects of methanol, acetonitrile, and acetone upon the line width of 81Br and 127I in the aqueous solutions. It was found that the viscosity plays a very important role upon the halide ions line width. There is no specific cation-halide ion interaction for those ions such as Mg++, Di+, Na+, and K+, whereas the Cs+ - halide ion interaction is strong. The effect of organic solvents upon the halide ion line width in aqueous solutions is in the order acetone ˃ acetonitrile ˃ methanol. It is suggested that halide ions do form some stable complex with the solvent molecules and the reason Cs+ can replace one of the ligands in the solvent-halide ion complex.

Part III

An unusually large isotope effect on the bridge hydrogen chemical shift of the enol form of pentanedione-2, 4(acetylacetone) and 3-methylpentanedione-2, 4 has been observed. An attempt has been made to interpret this effect. It is suggested from the deuterium isotope effect studies, temperature dependence of the bridge hydrogen chemical shift studies, IR studies in the OH, OD, and C=O stretch regions, and the HMO calculations, that there may probably be two structures for the enol form of acetylacetone. The difference between these two structures arises mainly from the electronic structure of the π-system. The relative population of these two structures at various temperatures for normal acetylacetone and at room temperature for the deuterated acetylacetone were calculated.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Chemistry and Physics)
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Minor Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Hughes, Edward Wesley
Thesis Committee:
  • Unknown, Unknown
Defense Date:21 November 1967
Record Number:CaltechTHESIS:12212015-083027456
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:12212015-083027456
DOI:10.7907/125N-CX62
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9335
Collection:CaltechTHESIS
Deposited By:INVALID USER
Deposited On:21 Dec 2015 17:49
Last Modified:22 Mar 2024 19:36

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