Characteristics of possible phases of the dense 3,4-connected net 'glitter' and other structural studies.

摘要

A. F. Wells' work in structural inorganic chemistry has led to many novel structure types some of which have been realized in natural and synthetic chemistry. Chapter One presents an introduction to this work. An examination of three dimensional nets with 3-connected, 4-connected and 3,4-connected vertices described by Wells, and of a paper by Hoffmann et al on the crystal and electronic structures of a series of 3,4-connected nets, led to the discovery of a novel 3,4-connected net built upon the 1,4-cyclohexadiene motif. The geometrical structure and electronic structure of this hypothetical net are described in Chapter Two.; Chapter Three describes a new diamond anvil cell design. High pressure cells are important for determining equations of state of materials and for related applications involving simultaneous pressure-temperature measurements. The high pressure chamber of the cell is constructed from the top and bottom diamond anvil faces and a gasket made from a refractory metal such as rhenium. A constant volume is maintained in the high pressure chamber based upon planimetric and interferometric measurements to high temperatures. Isochores of water have been measured to the phase boundary of the {dollar}alpha{dollar}-{dollar}beta{dollar} transition in quartz. Crystallographic studies of minerals immersed in water in the cell enable the pressure-temperature dependence of the lattice parameters to be determined.; The determination of the crystal structure of a nucleoside analog, 2-methylthio-6-{dollar}beta{dollar}-D-ribofuranosylimidazo (2,1-f) (1,2,4) triazin-4(3H)-one is discussed in Chapter Four. External dimensions of the single crystal were {dollar}sim{dollar}5 {dollar}mu{dollar} m x {dollar}sim{dollar}10 {dollar}mu{dollar} m x {dollar}rmsim{dollar}100 {dollar}mu m,{dollar} and because of this small external volume the data collection was limited to only several hundred unique reflections. A conventional four circle diffractometer was used to collect a set of data on the microcrystal and synchrotron radiation and a charge couple device (CCD) detector was used to collect another set of data. Structure solution using the synchrotron dataset yielded 19 of 21 heavy atoms by the program MULTAN 11/82. A difference Fourier map revealed the remaining two atoms. Isotropic refinement of this structure was carried out with the SHELXL 93 program to a reliability index of 5.75%. Anisotropic refinement yielded unphysical thermal ellipsoids for the heavy atoms. Presumably this was due to the microcrystal following a skewed path about the x-ray beam during data collection.