Cobalt(II) complexes with linear potentially pentadentate Schiff base ligands have been prepared and their reaction with dioxygen studied. The ligands were synthesized from salicylaldehyde and diamino compounds containing a central donor atom. Various derivatives were produced by using a substituted salicylaldehyde or by placing different groups on the compounds containing a central nitrogen donor. Those ligands containing weak central donors produce both four and five-coordinate complexes. The coordination number is determined by the electron density on the metal as well as the basicity of the central donor. The five-coordinate complexes assume a distorted trigonal bipyramidal structure, but the phosphorus containing complexes are believed to involve a different ligand arrangement from that of the other complexes. Most of the cobalt(II) complexes are stable in the solid state, but all react with oxygen in solution to some extent. A monomeric superoxo adduct was isolated with one of the complexes containing an unsubstituted central nitrogen donor. Other cobalt(II) complexes of this type react with oxygen to form dimeric peroxo adducts. An unusual dimeric dioxygen complex was obtained with a compound in which the central nitrogen donor is substituted with a methyl group. This adduct is believed to involve both superoxo and unreacted species. Comparison of the structure of precursors to that of a dimeric peroxo adduct suggests a different mode of bonding than that which occurs in dioxygen complexes with other types of ligands. The significance of this is explored in terms of the prevention of dimerization. / Ph. D.

Ph.D.

A valence bond perturbation method is developed for the purpose of treating the pi electron spectra of molecules related to a parent conjugated hydrocarbon molecule. A spectral perturbation reflects the change in pi electron transition energy of the parent hydrocarbon as a result of heteroatom replacement of one or more carbon atoms or introducing substituents. Such spectral perturbations may be correlated with inductive and mesomeric heteroatom or substituent effects. Preliminary studies involve a comparison of semi-empirical valence bond and molecular orbital methods using similar approximations and integral values in each. Zero order wave functions and energy eigenvalues required for the perturbation analysis are obtained from the semi-empirical valence bond calculation for butadiene. First order perturbation theory is applied to acrolein, gyloxal, acrylonitrile and methyl butadienes to study inductive effects. These molecules are iso-pi-electronic with butadiene. First and second order perturbation theory is applied to chloroprene, bromoprene, iodoprene and 1,4-dichlorobutadiene. Inductive effects as well as mesomeric effects which arise as a result of additional pi electrons contributing to the conjugated system by the halogen substituents are considered. Inductive and mesomeric effects of the halogen on spectral perturbations are separated and identified. Values for empirical parameters required for agreement between calculated and observed spectral perturbations are correlated with relative substituent or heteroatom inductive and mesomeric effects. / Ph. D.

Ph. D.

The knowledge of particle size and size distribution are important parameters for understanding the behavior of numerous colloid systems. These areas include for example, clays, viruses, paints and blood. Until recently this information could be obtained only by the use of expensive, slow and complex instrumentation. Hydrodynamic chromatography provides a means of investigating particles in the submicron and micron region. The separation mechanism of this method is based upon the flow parameters with which the solute particles interact as they pass through a packed column. In the past the interpretation of these chromatograms has been based upon the mathematical modeling of the column parameters. We have developed a new multiwavelength detector system to be used in conjunction with hydrodynamic chromatography which provides size and concentration information of the eluant directly. The result is a rugged system that provides size and size distribution information rapidly and at low cost. / Ph. D.

The reaction of substituted acetylacetonates with R₃B compounds leads to the production of an interesting series of chelates containing the pseudo-metal ion moiety, BR₂. [see document for image of chemical compound] When the substituents on the acetylacetone are capable of extensive delocalization with the chelate ring (e.g., benzoylacetomethane) and/or when the R groups on boron are sufficiently withdrawing (R = F, C₆H₅), these species are capable of reversible one-electron reduction to the radical ion. These ion radicals are extremely stable, having been kept for many months at room temperature under argon atmosphere. Previous studies have indicated that the dianion radical of the substituted acetylacetonate ligand itself is extremely unstable. It has been trapped at extremely low temperatures and its spectral properties have been reported. Obviously, the main group chelate radical ions that we have studied represent a case where the inherently unstable dianion radical system is stabilized by coordination to the pseudometal ion. The spin densities and charge distribution in the boron chelate radicals and the neutral parent have been calculated by Pariser-Parr-Pople SCF techniques, extended Hückel molecular orbital calculations, and CNDO and INDO methods. The ligand dianion radicals have also been successfully handled. In all cases, good agreement between experimentally observed ESR hyperfine coupling constants, assigned by satisfactory simulation, and calculated hyperfine constants have been obtained. The spin density calculations on the radical anions indicated that there are negligible spin delocalization over the moiety, BR₂. The net charge distribution in the neutral and the radical anions demonstrate that the effect of BR₂ on the radical stability is due to its withdrawing effect. The electronic energy levels and electronic transitions allowed in the neutral and the radical ions have been calculated by closed-shell and open-shell (RSCF) methods of Longuet-Higgins and Pople with the CI treatment of Ishitani and Nagakura. Good agreement with the experimental data is observed. Correlation diagrams connecting the MO levels for the neutral and radical ion species reveal information about the perturbations of energy levels caused by the injection of an extra electron into the previous spin-paired system. / Ph. D.

In 1933, benzo[a]pyrene, a hydrocarbon, which was and still is of very great importance for cancer research, was isolated from coal tar and also was synthesized. In recent years more than 450 synthetic compounds have been found to be carcinogenic, and more than 200 are polycyclic aromatic hydrocarbons, their derivatives and analogues. Recently a new polynuclear hydrocarbon, a seven ring compound naphtho[2,1-a]perylene was synthesized in This Laboratory Physiological tests have revealed this compound to be a potent carcinogen. This experience has prompted a new initiative to prepare a number of related compounds of this type in order to bring further insight to the relation between chemical structure and the mechanism of physiological activity. During the synthesis of the four new seven fused aromatic ring systems and a new eight fused aromatic ring system, several modifications and improvement of existing synthetic procedures were made. A recently published modification of the Rosenmund-von Braun method of nitrile synthesis was successfully applied to the preparation of 2-(2-naphthylmethyl)benzonitrile. It was found that 2-(2-naphthylmethyl)phenyl-1-naphthyl ketone and 2-(2-naphthylmethyl)phenyl-2-naphthyl ketone could be prepared by the reaction of a Grignard reagent with a nitrile as well as by the inverse addition of a Grignard reagent to the appropriate acid chlorides. The alumina cyclodehydrogenation procedure was confirmed to be the, only method of synthesis that yields 12-(1-naphthyl)-benz[a]anthracene from its precursor ketone. The yield of 12-(2-naphthyl)benz[a]anthracene was increased from 61% to 83% when anhydrous hydrogen fluoride was used in place of 48% hydrogen bromide and glacial acidic acid as the cyclodehydration media of the precursor ketone. A new cyclodehydrogenation procedure was developed. This procedure, which employs a mixture of aluminum chloride-stannic chloride and alumina, was used to prepare a new hydrocarbon, naphtho[l,2-a]-perylene. An aluminum chloride-sodium chloride melt permeated with carbon dioxide was successfully employed in the preparation of naphtho[2,2-1]benzo- (a]pyrene, naphtho(l,2-l]benzo[a]pyrene, and naphtho- (2,3-1]benzo[a]pyrene. It was shown that high temperature gas chromatography with ionization detectors can be used with success to analyze all of the above discussed ketones, benz[a]anthracenes as well as the new perylene and pyrenes. Additional support of the validity of the. structures of naphtho[1,2-a]perylene and naphtho- [2,1-1]benzo[a]pyrene was provided when the cyclodehydrogenation of these hydrocarbons yielded one and the same product, naphtho[l,7,8-efg]anthanthrene. It was observed that the correlation between color and structure of the newly prepared hydrocarbons follows the principles of annelation. When the ultraviolet and visible spectra peak frequencies were compared it was found that the values and positions of the peaks follow the principles of the annelation method. The examination of the infrared absorption spectra revealed that naphtho[l,2-a]perylene, naphtho[2,1l-1]benzo[a]pyrene, naphtho[1,2-1]benzo[a]-pyrene, and naphtho[2,3-1]benzo[a]pyrene exhibited Peaks at all four, "solo," "duo," "trio," and "quartet", carbon-hydrogen vibration regions, but as expected naphtho[1,7,8-efg]anthanthrene had the "quartet" carbon-hydrogen peak missing between 770 and 755 cm. which further substantiated the validity of the naphtho[1,7,8-efg]anthanthrene structure. The TNF molecular adducts of the five newly prepared compounds, naphtho[1,2-a]perylene, naphtho- [2,1-1]benzo[a]pyrene, naphtho1l,2-1]benzo[a]pyrene, naphtho[2,3-1]benzo[a]pyrene, and naphtho[1,7,8-efg]-anthanthrene were prepared and their melting points recorded. In order to ascertain the structures of the naphtho[1,2-a]perylene and the naphtho[1,2-l]benzo[a]-pyrene obtained from the cyclodehydrogenation of 12-(1-naphthyl)benz[a]anthracene and 12-(2-naphthyl)-benz[a]anthracene, respectively, other routes of synthesis were undertaken. The hydrocarbon, 11-(1-naphthyl)benz[a]anthracene, was prepared by the reaction of 1-naphthylmagnesium bromide with 11-keto-5,6,8,9,10,11-hexahydrobenz[a]- anthracene which on distillation under reduced pressure gave 11-(1-naphthyl)-5,6,8,9-tetrahydrobenz[a]anthracene and on aromatization yielded 11-(1-naphthyl)benz[a]-anthracene. When 1-naphthyl magnesium bromide was allowed to react with the 11-keto-8,9,10,11-tetrahydrobenz[a]anthracene, 11-(1-naphthyl)-8,9~dihydrobenz[a]anthracene was obtained when distilled under reduced pressure. This, likewise, gave 11-(1-naphthyl)- benz[a]anthracene on aromatization. Naphtho[1,2-a]perylene was synthesized unequivocally from 11-(1-naphthyl)benz[a]anthracene via a cyclodehydrogenation reaction. The hydrocarbon, 1-(1-naphthyl)-1,2,3,4-tetrahydrobenz[a]anthracene, was prepared by the reaction of 1-naphthylmagnesium bromide with 1-keto-1,2,3,4- tetrahydrobenz[a]anthracene. On distillation under reduced pressure 1-(1-naphthyl)-1,2,3,4-tetrahydrobenz[a]anthracene was obtained. Under the conditions of an aromatization procedure, naphtho[1,2-1]benzo[a]-pyrene was obtained. The hydrocarbons 11-(1l-naphthyl)-5,6,8,9-tetrahydrobenz[a]anthracene, 11-(1-naphthyl)-8,9-dihydrobenz[a]anthracene, 11-(1-naphthyl)benz[a]-anthracene, 1-(1-naphthyl)-1,2,3,4-tetrahydrobenz[a]anthracene are additional new compounds. / Ph. D.

Polyarylethers have been synthesized earlier via nucleophilic aromatic substitution, using aqueous caustic and polar solvent such as DMSO. This route even though rapid, suffers from serious limitations. We have modified this procedure considerably to synthesize a wide variety of high molecular weight polyarylethers. Our methodology utilized a higher boiling solvent namely N-methylpyrrolidone, a weak base such as K₂CO₃ and an azeotroping solvent such as toluene. Such a process allows one to synthesize the polymer in situ. We have also shown the feasibility of utilizing the procedure to synthesize functionally terminated controlled molecular weight oligomers. High molecular weight tetramethyl substituted bis A arylene ether ketones, sulfones, and nitrile functional polyarylethers have been synthesized successfully. The ketone containing tetramethyl bisphenol A polymers has been found to be a photocrosslinkable resin and hence a potential candidate as a negative photo-resist for electronic materials. Investigation of the thermal behavior of these polymers have indicated considerable interchain forces to be operating with the nitrile functional polymers. The nitrile functional polymers have been modified via hydrolysis to produce more hydrophilic and thermally stable amide functional polymers. Attempts at crosslinking the pendant nitrile groups via cyclization using Lewis acid were not as successful as expected. However, the use of the pendant nitrile group as a site for anionic grafting has been demonstrated. A wide variety of crystalline poly aryl ether ketones have been synthesized by using a modified synthetic strategy in which an amorphous polymer is first synthesized to high molecular weight in NMP and then chemically modified to produce crystalline polymers. All amorphous ketone functional polymers have been modified to produce, more hydrophilic, less thermally stable but potentially crosslinkable, alcohol functional polymers. All the homo and copolymers synthesized have been characterized at the molecular level by solution ¹³C NMR and FT-IR spectroscopy. Proton NMR was also used for compositional analysis. All polymers were also characterized thermally by DSC; other thermal characterization techniques such as TG and TMA have also been used. Molecular weight characterization included intrinsic viscosity measurement on all polymers and selective utilization of GPC. For crystalline insoluble polymers, solid state ¹³C NMR was used extensively for molecular level characterization. Wide angle x-ray measurement and DSC have been obtained in order to prove the existence and the level of crystallinity in these samples. Limited characterization by SEM and EDAX was also conducted, primarily to gain information concerning the surface structure. / Ph. D.

Ph. D.

All entirely new method had previously been perfected (1) for the determination of molecular weight of cellulose acetate in solution. The applicability of the dielectric dispersion method to other cellulosics was the next step in the development of this new procedure. Ethyl celluloee fractions were refractionated by a fractional precipitation procedure in order to obtain fractions that were homogeneous with respect to chain length. Ethyl acetate and acetone were used in the ratio of three to one (3:1) as solvents, and water acetone in the ratio of ninety-five to five (9515) was employed as a precipitating agent. The homogeneous ethyl cellulose fractions were investigated in a number of solvents – dioxane, benzene, toluene, carbon tetrachloride and n-butyl acetate. This was done in order that the applicability of different solvents could be observed as well as the relation between the viscosity and the critical frequency. The critical frequency is defined as the frequency at which the dispersion is fifty percent completed. 1. Havkine, M. C., Master of Science Thesis, Virginia Polytechnic Institute, 1956. / Ph. D.