Studies of the Mechanisms of Reactions of Binary Metal Carbonyls (open access)

Studies of the Mechanisms of Reactions of Binary Metal Carbonyls

A kinetic study of the reactions of Group VI-B hexacarbonyls with primary amine and halide ligands was undertaken in order to determine the possible mechanisms of these reactions. As well as the expected dissociative pathway, the reactions with the primary amines were seen to proceed by a concurrent pathway which was dependent upon the ligand concentration. Since nitrogen donor ligands are expected to be poor donor ligands, the mechanism proposed was a "dissociative interchange" mechanism which should not be too dependent upon the nucleophilicity of the ligand. Comparison of the rate constants for the amines studied as well as those of the previously investigated Lewis base ligands indicated all such reactions may proceed through the same mechanism. The similarity in rate constants for the ligand-independent and ligand-dependent pathways supports this mechanism. The rate of formation of the final product was seen to be dependent upon the square of the mercuric halide concentration. Therefore, the conversion of Fe(CO)4(HgX)2 to the final product was proposed to proceed by the successive abstraction by each HgX group of two molecules of mercuric halide. These oxidative elimination reactions are related to a chemical model for the intermediate step in the reduction of dinitrogen to ammonia …
Date: May 1977
Creator: Pardue, Jerry E.
System: The UNT Digital Library
Spectroscopic Investigation of Some Allyl Alkali Metal Compounds (open access)

Spectroscopic Investigation of Some Allyl Alkali Metal Compounds

To gain better understanding of the nature of the carbonmetal bonding in 3-neopentylallyl alkali metal (5,5-dimethyl- 2-hexenyl alkali metal) systems, an investigation is extended to 3-neopentylallylpotassium. In addition, pertinent data on the 3-neopentylallyl systems are re-examined in an attempt to understand the trends in the bonding habits, as affected by the solvent, the cation and the temperature.
Date: May 1976
Creator: Moore, Michael L.
System: The UNT Digital Library
Aldohaloketenes and the Stereochemistry of Aldohaloketene Cycloadditions (open access)

Aldohaloketenes and the Stereochemistry of Aldohaloketene Cycloadditions

The objective of this research problem was to synthesize aldohaloketenes and investigate the chemistry of this new class of ketenes.
Date: May 1970
Creator: Hoff, Edwin Frank
System: The UNT Digital Library
The Stereochemistry of the Cycloaddition of Unsymmetrical Phenyl Ketenes to Cyclopentadiene (open access)

The Stereochemistry of the Cycloaddition of Unsymmetrical Phenyl Ketenes to Cyclopentadiene

This dissertation is a study involving the synthesis and chemistry of arylhaloketenes and cyclopentadiene cycloadducts, and a study of the cycloadduct isomer distribution was begun.
Date: May 1970
Creator: Parry, Fred H.
System: The UNT Digital Library
Kinetic Studies and Vibrational Spectra of Disubstituted Metal Carbonyls (open access)

Kinetic Studies and Vibrational Spectra of Disubstituted Metal Carbonyls

The oxidative elimination reactions of (5-X-phen)Mo(C0)₄ (X = H, CH₃, Cl, NO₂; phen = o-phenanthroline) and (3,4,7,8-(CH₃)₄-phen)Mo(CO)₄ with mercuric chloride in acetone have been investigated. In these reactions, a carbon monoxide group is replaced by two univalent ligands, accompanied by the corresponding increase in coordination number and formal oxidation state of the central metal atom, to give products of the type, (X-phen)Mo(CO)₃(Cl)HgCl. With the exception of (3,4,7,8-(CH₃)₄-phen), the substituted o-phenanthrolines were selected so as to minimize steric differences from one substrate to another while obtaining the widest range of pKₐ of the ligand.
Date: May 1972
Creator: Jernigan, Robert Thorne
System: The UNT Digital Library
Electric Dichroism Spectroscopy in the Vacuum Ultraviolet (open access)

Electric Dichroism Spectroscopy in the Vacuum Ultraviolet

When a molecule, which possess a permanent dipole moment is exposed to an intense electric field, its absorption spectrum may be altered. These alterations are manifest as shifts in energy and as changes in band shape and intensity. The electric dichroism of absorption bands can be used to probe the excited state that is formed when a molecule undergoes a transition. The properties that may be investigated include transition polarization, excited state dipole moment and mean polarizability, and field-induced mixing of symmetrically equivalent excited states. The theoretical model and experimental devices that have been developed to determine these properties are presented and discussed. The data, taken in total, and its combination with other existing evidence, adds credence to the assignment of the second excited singlet of aldehydes and ketones to be extravalent, accompanied by relatively large delocalization of electronic charge, and polarized in-planiie and perpendicularly to the C-0 axis.
Date: May 1978
Creator: Causley, Gary C.
System: The UNT Digital Library
Halogenated 2-Oxetanones (open access)

Halogenated 2-Oxetanones

The purpose of this investigation is threefold: (1) to examine in detail the cycloaddition of halogenated ketenes and carbonyl compounds, (2) to study the decarboxylation of the resulting halogenated 2-oxetanones,and (3) to investigate the effect of halogens in the halogenated 2-oxetanones on the nucleophilic addition reaction.
Date: May 1973
Creator: Patel, Arvind D.
System: The UNT Digital Library
Hyperconjugative Interactions in Silylanilines (open access)

Hyperconjugative Interactions in Silylanilines

The purpose of the present work is to study the bonding interactions between the substituents and the ring π system for a series of ortho and para MeₙH₃₋ₙM (M = C or Si, n = 0-3) substituted N,N-dimethylaniline . Both ground and excited-state interactions were studied and their magnitudes determined. The experimental data were then used in conjunction with molecular orbital calculations to differentiate among inductive, hyperconjugative, and d-pπ interactions on the ground and excited states. Overall, the study indicates that d orbital involvement in the interactions of organosilicon substituents with unsaturated systems is much less significant than is generally held. The importance of pₛᵢ⁻π and pₛᵢ⁻π* hyperconjugative interactions between silicon σ* orbitals and π system in producing the effects of silicon substitution on unsaturated systems has become more apparent.
Date: May 1975
Creator: Jung, Il Nam
System: The UNT Digital Library
Organometallic Precursors to Cyclic Organosilanes (open access)

Organometallic Precursors to Cyclic Organosilanes

This investigation deals with the preparations of cyclic organosilanes via two different types of organometallic precursors: borane adducts to chlorovinylsilanes and tertbutyllithium adducts to chlorovinylsilanes. The regiospecificity of the hydroboration of various types of boranes to chlorovinylsilanes was studied by three different methods. It was found that, by using bulky hydroborating agents, about 80% isomerically pure terminal borane adducts to chlorovinylsilanes could be obtained. While the adducts are potential precursors to silacyclopropanes, when these borane adducts were treated with bases such as sodium methoxide and methyl Grignard, no evidence for silacyclopropane formation was found.
Date: May 1977
Creator: Lim, Thomas Fay-Oy
System: The UNT Digital Library