ACS MEETING - DALLAS, TEXAS 
ACS MEETING - DALLAS, TEXAS
The reaction of [(tBu)Ga(Te)]4 with elemental sulfur or selenium yields the corresponding cubane compounds, [(tBu)Ga(E)]4 (E = S, Se), via sequential chalcogenide exchange reactions. Each of the mixed cubane intermediate compounds, [(tBu)4Ga4(Te)4-x(E)x] (x = 1, 2, 3, 4) have been characterized by NMR spectroscopy and mass spectrometry. The kinetics of the chalcogenide exchange reactions have been investigated under pseudo first order conditions. The observed reactions are rationalized by a consideration of the relative reduction potentials of the chalcogens. In addition, the analogous reaction with iodine will be reported as well as metal exchange reactions.
The MOCVD growth of gallium sulfide (GaS) thin films will be reported using the dialkyl-dithiocarbamate precursors, (tBu)2Ga(S2CNR2) (R = Me, Et, nPr, iPr). The new precursor molecules have been characterized by NMR and IR spectroscopy and mass spectrometry, while their volatilities, including DH and DS of sublimation, have been determined by thermogravimetric analysis. Characterization of the thin films is accomplished by XRD and micro-probe analysis.
The objective of our research is the development of nano, meso, and macro scale aluminum based ceramic membranes and filters from carboxylate alumoxanes. Carboxylate alumoxanes are organic substituted alumina nano-particles synthesized from boehmite in aqueous solution which are an inexpensive and environmentally-benign precursor for the design and fabrication of these membranes. The size of the carboxylate ligand on the alumoxane controls the porosity during sintering to alumina. By varying the size of the ligand, membranes of different porosity can then be fabricated. The membranes will be characterized by atomic force, scanning electron, and transmission electron microscopy, X-ray diffraction, and flow measurements.
(1)
Sterically crowded aryloxide compounds of aluminum have been prepared with intra-molecular Lewis acid-base interactions (1) as model compounds for the latent Lewis acidity of alkyl-alumoxanes. A variety of Lewis base groups (ERx) are compared and their structures and reactivity are compared.
Carboxylate-alumoxanes, [Al(O)x(OH)y(O2CR)z], have been used as precursors to a-alumina bodies. The type of porosity in the resultant ceramic body is shown to be dependent on the identity of the carboxylate substituent (R). While the use of methoxyethoxyethoxyacetic acid [MEEA-H, HO2CCH2(OCH2CH2)2OCH3], methoxyethoxyacetic acid [MEA-H, HO2CCH2OCH2CH2OCH3], and methoxyacetic acid [MA-H, HO2CCH2OCH3] substituted alumoxanes results in the formation of inter-granular porosity, the acetic acid [A-H, HO2CCH2] allows for the formation of intra-granular pores. The formation of intra-granular porosity is discussed with respect to a self-seeding spontaneous nucleation process.
(1)
Continuing investigations of the formation, structure and reactivity of aluminum complexes of calixarenes will be presented. The structural control exerted by the aluminum alkyl substituent is demonstrated through the synthesis of an homologous series of compounds. The application of these compounds to Ziegler-Natta catalysis will be discussed.
(I)
Reaction of cyclic and linear siloxanes, (Me2SiO)n (n = 3, 4, 5), with R2AlH (R = tBu, iBu) results in the cleavage of Si-O bonds via a hydride shift to the Si and subsequent formation of an Al2O2 dimeric species, e.g., I. These species react further with R2AlH. The reaction of RAlH2(L) with (R2SiO)n is also detailed.
