The ligands of the ten-membered series, [10]-aneS3, [10]- aneS2N, [10]-aneSN2 and the macrobicyclic ligand - 1,4-bis(1-aza- 4,8-dithia-4-cyclodecyl) ethane, and their transition metal complexes were successfully synthesised. Chromium (III) complexes of the homoleptic hexaaza ligands [18]-aneN6 and [20]-aneN6 were synthesised, structurally characterised and their spectral properties studied. Bis complexes of Ni(II) with [10]-aneS3, [10]-aneS2N and [10]-aneSN2 were octahedral as is evident from their crystal structures. The esr spectra of the corresponding Ni(III) complexes are characteristic of a low spin d7 ion in a compressed octahedral coordination in the complex based on [10]-aneS2N and an elongated octahedral coordination in the complexes based on [10]-aneSN2 and [10]-aneS3. The spectral and electrochemical properties of the various Ni(II) complexes are compared with each other. The redox reactivity of the Ni(II) complex based on [10]-aneS3 was studied. The synthesis of a macrobicyclic ligand is described. The Ni(II)complex of the macrobicyclic ligand is a distorted octahedron and the esr spectrum of the Ni(III) complex is characteristic of a low spin d7 ion in a compressed geometry. The covalency parameter K, and the energy separation between the low spin ground state and the first excited high spin state were determined from the esr and the electronic spectra of the Ni(III) complex. Two isomers for the Pd(II) bis complexes of [10]-aneS2N were obtained and characterised by X-ray methods and nmr spectroscopy. Evidence for the formation of a high spin Pd(II) octahedral species has been provided for the first time. Oxidation of the Pd(II) complex is metal centered and the esr spectra of the Pd(III) complexes are characteristic of a low spin d7 PdS4N2 core. Fe(II), Fe (III), Co(II), Co(III), Ni (II) and Pd(ll) bis complexes of the ligand [10]-aneS3 were synthesised and characterised by elemental analysis, nmr and esr spectroscopies, where appropriate, and their spectral and electrochemical properties studied. The crystal structures of Fe(II), Co (II) and Ni(II) bis complexes of [10]-aneS3 were octahedral with three S atoms from each of the thioether ligands coordinated to the central metal ion. The esr spectra of the Fe(III) bis complexes of [9]-aneS3 and [10]-aneS3 were characteristic of a low spin d5 complex ion. The ligand field distortion parameters were obtained from the electronic and esr spectra and the energies of the Jahn-Teller splitting were estimated. The Co(II, bis complex of [10]-aneS3 is low spin. The half-wave potentials due to the [special characters omitted] and [special characters omitted] couples were obtained by cyclic voltammetry. The electron self exchange rate constant for the [special characters omitted] and the [special characters omitted] couples were determined by the 59Co nmr line broadening technique for the first time. The self exchange rate constant for the [special characters omitted] couple was determined by the 'H nmr line broadening technique. The crystal structure of the Pd(II) bis complex of [10]—aneS3 is essentially square planar with significant interactions from the axial S atoms. This complex is fluxional as is evidenced in the variable temperature nmr spectra. / Graduate

Non-genetic maternal influences on prenatal development have a significant effect on the development of early life behavior. This study assessed the behavioral effect of elevated prenatal progesterone on postnatal emotional reactivity, or underlying fear and stress, in embryos of Northern bobwhite quail (Colinus virginianus). Test groups of progesterone treated eggs, vehicle treated, and no injection were exposed to three measures of emotional reactivity at 48 and 96 hours after hatch: an open field, an emergence test, and a tonic immobility test. Heightened levels of emotional reactivity in the tonic immobility emergence tasks, and decreased levels of emotional reactivity in the open field suggest that elevated prenatal progesterone modifies post natal emotional reactivity up to 96 hours of age.

An array of carbazole-bis(azole) (CzTR and CzTrR, Cz = carbazole, T = tetrazole, Tr = triazole, R = Me, iPr, Bz and CH2Mes) pincer ligands were synthesized and fully characterized by NMR, X-ray crystallography and high resolution mass spectrometry. The physical properties of these ligands, as well as their applications in metal coordination compounds, were extensively studied. Mono, bis- and tris-ligand lanthanide (Y, Yb, Er, Sm, and Ce) complexes were synthesized and the solid state crystal structures of these complexes revealed the unusual binding modes of these ligands. The capability of these ligands to distort from planarity and bind in a fac type fashion, as well as bidentate, rather than tridentate modes was unexpected. The reactivity of the mono-ligand lanthanide complexes was explored and showed modest activity in ring-opening polymerization of lactones, as well as some unusual one electron redox chemistry. Bis-ligand complexes of some first row transition metals (Fe, Co, Ni and Zn) were also explored. These air-stable complexes proved invaluable in studying the physical properties of the ligands themselves, as well as the metal complexes. The bis-ligand zinc complexes (CzTiPr)2Zn and (CzTriPr)2Zn showed reversible oxidation of the CzT and CzTr ligands at modest potentials, as well as ligand-based fluorescence. Two bis-ligand iron complexes were synthesised using sterically diverse ligands (CzTiPr)2Fe and (CzTCH2Mes)2Fe and while (CzTCH2Mes)2Fe showed temperature-independent paramagnetism, the similar (CzTiPr)2Fe complex showed a two-step thermally induced spin crossover phenomenon near room temperature in the solid state. The oxidation of (CzTiPr)2Fe yielded [(CzTiPr)2Fe]+ BF4-; we have speculated that this complex is initially oxidized at the ligand and then undergoes an electron transfer from the metal to the ligand to result in an Fe(III) complex. Mono-ligand iron complexes using the CzTiPr ligand were also synthesized. While ligand redistribution hindered initial progress, the use of a bulky phenoxide ancillary ligand arrested the redistribution pathway and allowed the synthesis of (CzTiPr)Fe(OAr)(THF). This iron complex proved to be the most successful in terms of isolating stable and reactive complexes with our ligands, and several adducts (THF, tBuNC, TPPO) were synthesized. Synthetic and DFT studies of these complexes demonstrated the tendency for the Fe to bind σ-donor ligands, but not π-acceptor ligands. This led to the isolation of a thermally sensitive four-coordinate iron complex (CzTiPr)Fe(OAr). The catalytic activity of these Fe phenoxide complexes in the hydrosilylation of styrene with phenylsilane was explored. These catalysts were able to selectively produce the Markovnikov hydrosilylation product with good activity. The apparent preservation of the Fe(II) oxidation state throughout the catalytic transformation suggests a possible ligand-assisted mechanism where the CzT ligand acts as a proton reservoir. / Graduate / 2021-11-23

Abstract: The choice ofsuitable ligand platforms is crucial to organometallic coordination chemistry and homogeneous catalysis. Among the various ligand platforms available, pincer ligands offer a convenient route to manipulate the properties of the resulting complexes. The pincer chemistry of rhodium has attracted attention for over 40 years, and Rh complexes are dominated by Rh(I) and Rh(III) low-spin states, thus they are more predictable than other paramagnetic species. Compared to other pincer ligand platforms, pyridine-based pincer complexes are particularly attractive as they exhibit diverse reactivities. Our group realized a new class of the PN3 (P) pincer system, with altered the unique catalytic performances, thermodynamic and kinetic properties due to their pseudo-dearomatized nature. In Chapter 2, selective carbonylation of benzene to benzaldehyde using a phosphorus nitrogen PN3P Rh(I) complex was realized. The PN3P Rh pincer chloride complex cPePN3PRhCl was capable of activating C−H bond of benzene to give the phenyl complex cPePN3PRh(C6H5) using KN(SiMe3)2 as a base. Furthermore, the benzoyl complex cPePN3PRh(CO)(C6H5) was obtained by treating a benzene solution of cPePN3PRh(C6H5) with CO gas. In dilute HCl, a high yield of 90% benzaldehyde was formed with regeneration of the cPePN3PRhCl. This is the first example of selective carbonylation of benzene into benzaldehyde accomplished by directly inserting CO without irradiation. In Chapter 3, the ligand-centered reactivity of a pseudo-dearomatized PN3P *rhodium complex towards molecular oxygen wasrealized. For the dearomatized rhodium carbonyl complex (tBuPN3P*RhCO), one of the C−H bonds of the pseudo-dearomatized pyridine ring was oxidized by O2 to create an α, β-unsaturated carbonyl functionality. Moreover, the resulting metal complex with the post-modified PN3P ligand could react with thiophenol and 4-methylaniline to afford the corresponding oxidative Michael addition products. In Chapter 4, to further explore the ligand-centered reactivity of tBuPN3P *RhCO, a series of second-generation diimine-amido PN3P-pincer carbonyl complexes were synthesized by reaction of tBuPN3P*RhCO and various alkyl/benzyl halides via a post-modification strategy, and these complexes were well characterized by NMR, HRMS, FT-IR, and single crystal diffraction. Moreover, a plausible mechanism for the formation of 2nd -generation PN3P complexes was proposed

The mechanism or a thermal amino group transfer-fragmentation reaction yielding carboxyamides from mixed phosphoric-carboxylic anhydrides (RO(R¹R²N)P(O)OC(O)R³; R = R¹ = alkyl; R² = H, alkyl, aryl; R³ = alkyl, aryl) was elucidated from structure reactivity studies using a model system, R = R¹ = R² = Me, R³ = Ph. Kinetic data was obtained using ¹H nmr spectroscopy; MNDO molecular orbital and molecular mechanics calculations, and the crystal structure or N-methyl-2-benzoyloxy-2-oxo-1, 3, 2-oxazaphosphorinane (Pna2₁; a = 22.229(6)Å, b = 7.597(2)Å, c = 7.210(2)Å; v = 1217.6(6)ų. Final R = 3. 08% for 1037 reflections with I (rel )> 2αI (rel) and 15 7 parameters) were userul in providing additional in formation about the reaction mechanism .

This experiment tested three hypotheses regarding right cerebral involvement in hostility and physiological arousal. First, replication of previous research indicating heightened physiological responding to stress among high hostile individuals was attempted. Second, high hostile individuals were predicted to an increased tendency toward right hemisphere dominance following exposure to a stressor. Third, high hostile individuals were expected to maintain their physiological arousal and shift in cerebral laterality longer than the low-hostile comparison group. Low- and high-hostile participants (25 males per group, drawn from the undergraduate Psychology pool) were identified using the Cook-Medley Hostility Scale (CMHS). Physiological measures (SBP, DBP, HR) were recorded at baseline, as were results from a dichotic listening procedure. Participants were then administered the cold-pressor procedure, and physiological recordings were taken again. Dichotic listening procedures were then administered 3 consecutive times to monitor for shifts in cerebral laterality. After the final dichotic listening procedure, physiological measures were taken once again to determine recovery rates. Results did not support the a priori hypotheses. Specifically, low-hostile individuals were consistently higher on the physiological measures when compared to the high-hostiles. The predicted maintenance of increased physiological arousal was also not supported by the data. Neuropsychological measures also failed to differentiate between the groups, and failed to demonstrate the predicted shift in cerebral laterality. / Master of Science

The aim of the current study was to examine how thinking about qualitatively different social network members may differentially affect cardiovascular reactivity to a subsequent stressor. Eighty-two undergraduates were asked to think and write about different types of relationships preceding a social stressor. No differences between conditions in CVR were found during social support induction phase or the stressor task. Women in the supportive condition were found to have slower SV recovery than those in the ambivalent condition. The results of this study are inconsistent with previous evidence for a relationship between mental representations of social ties and CVR. Future research should seek to rule out confounding variables and clarify this effect.

No description available.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Vita. / Includes bibliographical references. / by Scott M. Rocklage. / Ph.D.

La réactivité totale OH est la perte totale du radical hydroxyle (le principal oxydant de l'atmosphère) avec les gaz réactifs dans l'air ambiant. Elle représente la mesure de la quantité totale des réactifs dans un environnement donné.Nous présentons ici un travail expérimental se concentrant sur les améliorations techniques d'une méthode appelée "Comparative Reactivity Method" pour mesurer la réactivité OH su le terrain ainsi que sur des résultats obtenus sur deux sites ciblés dans le bassin méditerranéen.La réactivité OH mesurée était élevée dans les deux sites. Sur le site récepteur en Corse (France) au cours de l'été 2013, nous avons observé que la réactivité OH était en moyenne de 5,5 s-1 (avec un maximum de 17 s-1). Ces mesures ont été comparées avec les observations de composés en phase gazeuse réalisées pendant la campagne. Il a été noté que pendant une période de la campagne, seulement 50% de la réactvité était expliqué par les mesures complémentaires.Lors de mesures dans une forêt de chênes pubescents, émetteurs isoprène, dans le sud de la France, nous avons observé que la réactivité OH maximale était très élevée (69 s-1), en accord avec la réactivité calculée à partir des mesures des gaz réactifs.Ce travail de thèse met en évidence que: (i) le bassin méditerranéen est un fort émetteur de gaz réactifs, (ii) la réactivité mesurée dans ces deux sites de la Méditerranée a été fortement impactée par les émissions biogéniques, (iii) il reste encore beaucoup de composés inconnus associés aux émissions biogéniques primaires et secondaires. A l'avenir, plusieurs approches pourraient etre utilisées pour identifier ces composés inconnus: en couplant la mesure de la réactivité OH avec des mesures de plantes dans des enceintes fermées (composés primaires), études en chambre de vieillissement (composés primaires et secondaires), ainsi que des approches de modélisation. / The total OH reactivity is the total loss rate of the hydroxyl radical with the reactive gases in ambient air. It represents the measure of the total loading of reactants in a given environment.Here we present an experimental work focusing on the technical improvements of the Comparative Reactivity Method to measure the OH reactivity on the field and field measurements of OH reactivity at two targeted sites in the Mediterranean basin.The measured OH reactivity was high at both sites. At a receptor site in Corsica (France) during summer 2013, we observed that the OH reactivity was maximum 17 s-1, on average 5.5 s-1 and during one week only 50% was explained by the complementary measurements in the gas phase.At a forest of downy oak trees, high isoprene emitters, in the south of France, we observed that the OH reactivity was maximum 69 s-1, in agreement with the reactivity calculated from the measurements of reactive gases only during daytime.This thesis work highlights that: (i) the Mediterranean basin is a strong emitter of reactive gases, (ii) the reactivity measured in these two sites in the Mediterranean was strongly impacted by the biogenic emissions, (iii) there are still many unknowns associated to measures of biogenic volatiles primary emitted and secondary produced. Such unknowns might be reduced in the future by coupling the measurement of the OH reactivity with plants enclosures and chambers studies as well as modelling approaches.