Dodecameric (Sn ) and hexameric topologies dominate monoalkyltin-oxo cluster chemistry. Their condensation, triggered by radiation exposure, recently produced unprecedented patterning performance in EUV lithography. A new cluster topology was crystallized from industrial n-BuSnOOH, and additional characterization techniques indicate other clusters are present. Single-crystal X-ray analysis reveals a β-Keggin cluster, which is known but less common than other Keggin isomers in polyoxometalate and polyoxocation chemistry. The structure is formulated [NaO (BuSn) (OH) (O) (OCH ) (Sn(H O) )] (β-NaSn ). SAXS, NMR, and ESI MS differentiate β-NaSn , Sn , and other clusters present in crude "n-BuSnOOH" and highlight the role of Na as a template for alkyltin Keggin clusters. Unlike other alkyltin clusters that are cationic, β-NaSn is neutral. Consequently, it stands as a unique model system, absent of counterions, to study the transformation of clusters to films and nanopatterns.

Mixed monolayers of thiol-terminated (T) and methyl-terminated (Me) carboxylic acids on nanocrystalline TiO(2) films underwent dimerization-induced compositional changes. At short reaction times, the compositions of mixed monolayers were kinetically controlled and mirrored the compositions of coadsorption solutions. On time scales up to several hours, well after the establishment of saturation surface coverages, the monolayers relaxed to thermodynamically controlled compositions through the displacement of Me by T. Equilibration was driven by the formation of intermolecular disulfide bonds between thiol groups of adsorbed T, which yielded polydentate dimeric adsorbates that were bound more strongly than monomeric adsorbates to TiO(2). The rate of compositional changes increased with decreasing solvent viscosity and decreasing alkyl chain length of T, suggesting that the rate of adsorption of T to TiO(2) strongly influenced the overall kinetics under certain conditions. Steric bulk within adsorbates and the strength of surface-attachment interactions also influenced the rate of compositional changes. A kinetic model, derived on the basis of Langmuir adsorption and desorption kinetics, accounts for key aspects of the mixed-monolayer compositional changes. The rate-determining step in the overall mechanism involved either the adsorption of T or the formation of disulfide bonds, depending on the conditions under which monolayers were prepared. Our findings illustrate that dimerization and other intermolecular interactions between adsorbates may dramatically influence the composition and terminal functionalization of mixed monolayers.

Rare earth oxide materials, including thin film coatings, are critically important in magnetic, luminescent and microelectric devices, and few substitutes have been discovered with comparable performance. Thin film coatings from solution are almost unknown for rare earth oxides, likely due to their high activity towards hydrolysis which yields poor quality thin films. The hexamer [Ln(O)(OH)(HO)(NO)] is a rare example of a metal-oxo cluster isolated and stabilized without additional supporting organic ligands. Herein we report a new method for both the preparation and stabilization in non-aqueous media, which makes these clusters valuable precursors for solution-processed thin films. Solution characterization (NMR, small-angle X-ray scattering and Raman spectroscopy) in wet organic solvents indicated that the clusters evolve via a fragmentation and reaggregation process. This is especially true for hexamers of the smaller Ln-ions: the higher charge density yields higher hydration rates. This process produced an entirely new hexadecameric cluster formulated YO(OH)(NO)(OSMe)(OCMe)(HO). The new structure represents an intermediate hydrolysis product on the pathway from hexanuclear clusters to metal oxyhydroxide bulk solid. DMSO solvent ligands displace aqua ligands on the cluster and likely explain the additional stability observed for these clusters in organic solvents. The enhanced cluster stability in DMF and DMSO also enables solution-processing methods to create high quality thin films.

A series of five organotin carboxylates of the type [RSn(O)O 2 CR'] 6 containing n-butyl ligands and carboxylates ranging in size from formate to diphenylacetate were synthesized and examined by single crystal X-ray diffraction. The crystal and packing structures of each compound were compared with regards to the steric and intermolecular forces of the varying carboxylate groups in order to aid the understanding of how these same factors relate to irradiation trends in EUV lithography of thin films. The trends found are compared to other factors that may also dictate resist formation in order to elucidate a fuller picture of the chemical transformations that occur when patterning inorganic materials.