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Ninety square planar Rh(I) complexes of the type cis-[Rh(CO)₂(X)(L)], [Rh(COD)(X)(L)], [Rh(CO)₂(L)₂]ClO₄ and [Rh(COD)(L)₂]ClO₄ (X is Cl or Br; COD is 1,5-cyclooctadiene; L is aniline, pyridine, pyridine N-oxide, imidazole and ammonia), as well as their isotopically labelled derivatives (¹³CO, ²H and ¹⁵N) were prepared, characterized by microanalysis and melting point, and investigated by the following spectroscopic techniques: infrared, Raman, ultraviolet, mass spectrometry, and 1H, ¹³C and ¹⁵N nmr spectroscopy. The comprehensive isotopic labelling studies allowed unambiguous assignment of the infrared modes in the 4000-50 cm⁻¹ region. The infrared assignments are discussed with reference to their vᴰ/Vᴴ ratios, the various ligands and halogens used, the charges on the complexes, and are compared to similar compounds. The 1H, ¹³C and ¹⁵N nmr runs were performed at room and low temperatures. Fluxionality of the ligands (L) was observed and the exchange process was monitored by variable temperature nmr. The enthalpy and entropy values for the intermolecular exchange of L in the complexes cis-[Rh(CO)₂(X)(L)] were obtained by a complete computer simulated band shape analysis of the carbonyl region of the ¹³C nmr spectra. The non-equivalence, and specific assignment of the carbonyl groups in the cis- [ Rh(CO)₂(X)(L)] complexes were determined by recording the variable temperature ¹³C nmr spectra of the doubly enriched species cis[Rh(¹³CO)₂(X)(¹⁵N-ligand)]. ²J(¹³C-Rh-¹⁵N) values are reported for the first time. The ¹J(¹⁵N-¹⁰³Rh) coupling constants are rationalized in terms of the metal-nitrogen bonding, and correlate with the s-character of the bonding electron on nitrogen. While the solution electronic spectra reveal that the complexes are discrete monomeric entities in solution, there are indications of metal-metal interactions in the solid-state. The normal coordinate analysis study of the complexes cis-[Rh(CO)₂(X)(L)] involved the calculation of a general valence force field by applying the eigenvector method of Becher and Mattes. The results show that point-mass-modelling and simplified force field, as assumed in our treatment, describes, to a good approximation, the vibrational properties of the complexes. The potential energy distribution provided further support for the proposed infrared assignments of the complexes.

by Ho Kai Wing Kevin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 94-98). / ABSTRACT --- p.iv / ACKNOWLEDGEMENTS --- p.vi / Chapter CHAPTER ONE: --- INTRODUCTION --- p.1 / Chapter 1.1 --- Basic Co-NMR Theory --- p.1 / Chapter 1.2 --- Method Employed --- p.5 / Chapter 1.2.1 --- Solvent Dependent Studies on Cobalt(III) complexes using 59Co NMR Spectroscopy --- p.5 / Chapter 1.2.2 --- Relationship between δiso and NQCC of Cobalt(III) Complexes in Solid --- p.7 / Chapter 1.3 --- Donor Acceptor Interactions --- p.8 / Chapter 1.4 --- Objectives of this Thesis --- p.10 / Chapter CHAPTER TWO: --- EXPERIMENTAL --- p.11 / Chapter 2.1 --- Synthesis --- p.11 / Chapter 2.2 --- NMR Measurements --- p.13 / Chapter 2.2.1 --- 59Co NMR Measurements --- p.13 / Chapter 2.2.2 --- 13c NMR Measurements (T1 Measurements) --- p.14 / Chapter 2.3 --- Viscosity Measurements --- p.15 / Chapter 2.4 --- UV-Vis Spectral Measurements --- p.15 / Chapter CHAPTER THREE --- 59Co NMR STUDY OF MAGNETIC COBALT(III) COMPLEXES --- p.16 / Chapter 3.1 --- Solvent-Dependent Studies of Cobalt(III) Complexes --- p.16 / Chapter 3.1.1 --- "Study of [Co(en)3]Cl3 and cis, trans-[Co(en)2(N3)2]NO3" --- p.17 / Chapter 3.1.2 --- Study of trans- [Co(en)2(NH3)2]Cl3 and trans- [Co(en)2(N02)2]NO3 --- p.29 / Chapter 3.1.3 --- "Study of trans- Na[Co(acac)2 (N02)2],trans- [Co(acac)2(N02)(NH3)] and trans-[Co(acac)2(NH3)2]I" --- p.36 / Chapter 3.1.4 --- Summary --- p.48 / Chapter 3.2 --- "Simultaneous Determination of CSA, ic, and NQCC of Cobalt(III) complexes in Different Solvents" --- p.49 / Chapter 3.2.1 --- Method --- p.49 / Chapter 3.2.2 --- "Study of trans- Na[Co(acac)2(N02)2],trans- [Co(acac)2(N02)(NH3)] and trans-[Co(acac)2(NH3)2]I and trans-[Co(acac)2(MeNH2)2]I" --- p.52 / Chapter 3.2.3 --- Study of trans- [Co(en)2(N〇2)2]N03 and trans- [Co(en)2(NCS)2]NCS --- p.58 / Chapter 3.2.4 --- Study of trans- [Co(en)2(NH3)2]Cl3 and trans- [Co(en)2(N3)2]NO3 --- p.63 / Chapter 3.2.5 --- Summary --- p.68 / Chapter 3.3 --- Resolution of the d-d Electronic Transition Energies in Cobalt Complexes and its Application to the Donor-Acceptor Interactionsin Cobalt Complexes - Application of Equation 3.3.1 --- p.70 / Chapter 3.3.1 --- Method --- p.70 / Chapter 3.3.2 --- "Study of trans- [Co(en)2(N02)2]N03,trans- [Co(en)2(NCS)2]NCS, trans- [Co(en)2(N3)2]N03 and trans- [Co(en)2(NH3)2]Cl3" --- p.72 / Chapter 3.3.3 --- "Study of trans- Na[Co(acac)2(NO2)2],trans- [Co(acac)2(N02)(NH3)] and trans-[Co(acac)2(NH3)2]I" --- p.86 / Chapter CHAPTER FOUR --- CONCLUSION AND FUTURE WORKS --- p.92 / REFERENCES --- p.94

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Ph.D. / Organic Chemistry / The use of electron impact mass spectrometry for isotopic analysis is an established technique; however, its application to problems involving biologically produced molecules enriched in 13C has been severely limited. This limitation is shown to arise because of data reduction techniques which are, for practical purposes, incapable of dealing with the complex situation of multiple enrichment sites, limited isotope abundance, and complex spectral regions. Two approaches for detailed isotopic analysis of EIMS intensity are presented and illustrated using model data, literature data, and original data from biosynthetically enriched compounds. The first approach which allows for sequential variation of any one parameter is shown to be of value in experimental design through construction of ion cluster contour diagrams which summarize the variation of isotopic distribution, molecular size, and uncertainty in measurement with total isotopic content. The second approach differs in concept from previous methods and is especially promising for application to problems involving multiple sites of enrichment, limited isotopic abundance, and complex spectral regions. The key concept of this approach is that the roots of the polynomials constructed from observed spectral intensities are analytically related to the isotopic content and the isotopic distribution of the ions giving rise to the intensities.

Graduation date: 1992

A. Roberts, Y. Beers [and] A.G. Hill. / "June 6, 1949." / Includes bibliographical references. / Army Signal Corps Contract No. W-36-039-sc-32037 Project No. 102B. Dept. of the Army Project No. 3-99-10-022.

AbstractIn this study a coincidence circuit composed of Ortec modules with Ge(Li)-NaI(Tl) detectors was utilized. An investigation of the different fractional threshold settings of a Constant Fraction of Pulse Height Trigger was made.Two different isotopes were investigated. A sample of 22Na was used as a prompt source. The half-life of the 0.081 Mev energy levelof 133Cs was studied. This half-life has been reported as being 6.3 nsec. Results were compared with results of a previous study at Ball State University which had used a conventional single channel analyzer and had used the zero crossover point for timing purposes.The best value received for the 133Cs energy state using a slope measurement was 8.12 t 0.25 nsec. Using a centroid shift measurement the best value of the 133Cs energy state was 5.66 nsec.Ball State UniversityMuncie, IN 47306