Nancy T. Kawai

Main Group Metal Halide Complexes with Sterically Hindered Thioureas: Part XVII. The Crystal and Molecular Structures of Two New Tellurium Chloride Complexes with 1,3-dimethyl-2(3H)-imidazolethione

Abstract In an attempt to determine the crystal and molecular structure of previously reported [TeCl2(dmit)4] (1) [dmit=1,3-dimethyl-2(3H)-imidazolethione], recrystallization in hot acetonitrile yielded two new complexes, [TeCl2(dmit)2] (2) and [TeCl4(dmit)2] (3) as determined by X-ray crystallography. The structure of 2 consists of a cis-substituted square planar geometry with the thione rings both oriented on the same side of the TeS2Cl2 plane. The complex undergoes very slow decomposition in air. The structure of 3 is a near-octahedral arrangement with the thione ligands trans to each other

The Order-Disorder Phase Transition in the Cage Hydrocarbon Quadricyclane

Abstract The phase behavior of quadricyclane has been investigated by differential scanning calorimetry and vibrational spectroscopy. An order-disorder phase transition occurs at 153 K on cooling and at 180 K on heating.

Effect of high pressure on the infrared spectra of the thiamine enzyme ‘active aldehyde’ intermediate 2-(α-hydroxybenzyl)thiamine chloride (HBT) and the mercury(II) complex, Hg(HBT)Cl3

Abstract The effects of high external pressures (∼30 kbar) on the IR spectra of the protonated form of 2-(α-hydroxybenzyl)thiamine chloride (HBT·HCl) and the zwitterionic mercury(II) complex Hg(HBT)Cl 3 have been investigated at room temperature. With the exception of the v (OH) peak of the HBT ligand, all the observed peaks shift towards higher wavenumbers with increasing pressure. The most pressure-sensitive peaks (d v /d P >;0.6 cm −1 /kbar) are chiefly associated with vibrations of the pyrimidine ring. The S conformation of the pyrimidine and thiazolium rings is apparently retained under high pressure in both HBT and Hg(HBT)Cl 3 , as is also the case in solution.

High‐pressure studies of the vibrational spectra of 1,4‐dibromo‐ and 1,4‐diiodocubane

The Raman and infrared spectra of 1,4-dibromo- and 1,4-diiodocubane were measured in the solid state and the peak splittings correlated with their crystal structures. The pressure dependences of the vibrational modes of the dibromocubane were studied. Neither compound appears to exhibit a phase transition in the solid state either as a function of temperature between 103 and 500 K or, in the case of dibromocubane, as a function of pressure up to 15 kbar. Copyright

Pressure-tuning FT-Raman spectroscopy

Pressure-tuning dispersive Raman spectroscopy, using diamond anvil cells, has many of the common limitations of Raman spectroscopy such as low signal intensity, as well as photodecomposition and fluorescence of many samples. In the present investigations, the pressure-tuning experiment has been successfully coupled to an FT-Raman spectrometer using a microscope for sample alignment and measurement. The use of a holographic notch filter to eliminate the intense scattering due to the diamond anvil cell is discussed and studies involving organometallic complex, polymers, and biomolecules are presented.