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Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 116-126).

<p>The phenomenon of spontaneous growth of metallic filaments, known as whisker growth has been studied. Until now the problem that Sn whisker growth could cause in electronics by making shorts has been partially prohibited as Pb and Sn have been used together in solders and coating. Regulations restricting Pb use in electronics has made the need to understand Sn whisker growth more current.</p><p>It is shown that whiskers are highly resilient towards vibrations and shocks. A Sn whisker is shown to withstand 55 mA.</p><p>Results show that reflowing of the Sn plated surface does not prevent extensive whisker growth. Results show that intermetallic compound growth can not be the sole reason behind whisker growth. Nickel and silver underlayer have been shown not to prevent whisker growth, but perhaps restrain whisker growth. Heat treatment damped whisker growth considerably. It is judged that base material CuSn6 is less prone to show whisker growth than CuSn0.15 and E-Cu58.</p>

The phenomenon of spontaneous growth of metallic filaments, known as whisker growth has been studied. Until now the problem that Sn whisker growth could cause in electronics by making shorts has been partially prohibited as Pb and Sn have been used together in solders and coating. Regulations restricting Pb use in electronics has made the need to understand Sn whisker growth more current. It is shown that whiskers are highly resilient towards vibrations and shocks. A Sn whisker is shown to withstand 55 mA. Results show that reflowing of the Sn plated surface does not prevent extensive whisker growth. Results show that intermetallic compound growth can not be the sole reason behind whisker growth. Nickel and silver underlayer have been shown not to prevent whisker growth, but perhaps restrain whisker growth. Heat treatment damped whisker growth considerably. It is judged that base material CuSn6 is less prone to show whisker growth than CuSn0.15 and E-Cu58.

Tri(2-thiophenyl)phosphine (P(C6H4-2-SH)3,PS3) was designed at 1989. Recently chemists use this ligand for enzyme models because it provides rich sulfur environment. Some chemists use PS3 to synthesize novel metal complexes. This thesis deals with the synthesis and structural discussion of germanium and tin complexes bearing PS3 ligands. Reactions with different metal source all yield novel structures. Reaction of GeCl4 with PS3 gives supramolecular structures with continuous £k-£k interaction. Similar reaction with GeCl3Me gives crystals in optically active form in stead of the usual optically inactive racemic form. Reaction with SnCl4 gives six-coordinate dimmeric tin complex (Sn(OMe)(PS3))2 with bridging methoxyl group and thiolate group (from PS3). Reactions using SnCl3Et or SnCl3Bu as metal sources followed by sublimation (140oC , 10-2torr) give reductive elimination products with alkyl groups transferred onto sulfur atom. These two structures are similar in morphology but different in skeletal arrangement.

Tri(2-thiophenyl)phosphine (P(C6H4-2-SH)3, PS3) was designed at 1989. Recently chemists use this ligand for enzyme models because it provides rich sulfur environment. Some chemists use PS3 to synthesize novel metal complexes. Others study the transmetalation of PS3 tin complexes with FeCl3. As a continuation of our long time interest in these tin complexes as alkylation reagents, this thesis reports the synthesis and characterization of the tin-PS3 complexes. Reactions using SnCl3Me or SnCl3Bu as metal sources when dissolved in DMSO gave DMSO adduct of PS3 tin complex while sublimation gave reductive elimination products with alkyl groups transferred onto sulfur atom. The butyl transferred product and its methyl analogous are similar in morphology but different in skeletal arrangement. Reaction of SnCl4 with PS3 gave two different crystals after long standing. One is the hydrolysed product, [Sn(OH)(PS3)]2, with bridging hydroxyl groups and thiolate groups. The other is the product with oxidized ligand. Reaction of SnBr4 with PS3 gave analogous ligand-oxidized product. Reaction of two mole of SnCl3Bu with PS3 resulted in a bimetallic tin complex.

In our previous studies on modeling methyl transfer protein, Ada protein, we found that zinc complexes of tri(2-thiophenyl)phosphine (PS3), (A), have similar methyl transfer behavior as its biological counter part. In order to probe the role of zinc in methylation process, we used tin and cadmium in model study to compare their chemistry relative to that of zinc. We found that all three metal complexes have similar chemistry and assume similar dimeric anion structure. For example, [Cd(PS3)]22-(1) and [Cd(SiPS3)]22-(2) have been successfully characterized crystallographically to possess the same structure as zinc dimer (A). However , in attempt to crystallize the tin analogue, the accidental oxidation product [SnIV(OH)2(SiPS3)]2, (5), was obtained. Its crystal structure gave clue to the mechanism of oxidation of the original tin dimer. The reactions with alkylating reagent of (1) have been compared with those of zinc dimer (A), and we found that the metal (Zn or Cd) center causes the dimers to produce different degree of methylation products toward different alkylating reagents. For the reactions with CH3I, the different degree of methylation between Cd and Zn dimers shows that the presence of zinc center has higher methylation selectivity and weaker reactivity.

<p>This thesis deals with the influence of the structure andchemical composition of platinum surfaces on the adsorption ofsome molecules. Three main lines can be distinguished : 1) thecharacterisation of clean/modified surfaces, 2) the adsorptionof some simple atoms and molecules on these surfaces andfinally 3) the adsorption of 2-butenal, a bi-functionalmolecule containing a C=C group conjugated with a C=O group.The main tools used in this work are scanning tunnellingmicroscopy, photoelectron spectroscopy and high-resolutionelectron energy loss spectroscopy, in combination with quantumchemical calculations.</p><p>The platinum (111)(1× 1) and (110)(1× 2) surfacesare chosen as substrates. Pt(111) is a non-reconstructedclose-packed surface, while the Pt(110) surface is open, due toits missing row (MR) reconstruction, which results in thealternation of ridges, {111} microfacets and valleys. Titaniumgrows on Pt(111) in a Volmer-Weber mode. Pronounced reactionsbetween Pt and Ti are detected already at room temperature asthe Ti2p and Pt4f_7/2core-level shifts are characteristic of the Pt₃Ti alloy. Carbon segregated on the (110) surfaceappears as extended graphitic regions, which smoothen thesubstrate. Sn deposition at room temperature on Pt(110) resultsin the appearance of small islands, randomly spread over thesurface. The presence of mobile Sn ad-atoms and Pt-Sn-Ptalloyed chains in the valley of the MR reconstruction is alsoevidenced. Annealing the surface results in the rearrangementof the tin in the surface layer, together with a globalshortening of the terraces in the [110]direction and anincreased density of (1× n) (n>2) defects.</p><p>The adsorption of atomic hydrogen and oxygen has beenperformed on the Pt(111)( √ 3x √3)R30º surfacealloy and on Pt(110)(1× 2) respectively. The adsorptionsite of these atoms is changed as compared to the onedetermined on the clean Pt(111) surface (i.e. fcc hollow site): H is adsorbed on-top site on the (√3× √3)surface alloy, and O sits on the ridge of the missing rowreconstruction in bridge site. Carbon monoxide adsorption wasperformed on Pt(111) and Pt(110)(1× 2) surfaces, modifiedor not by tin. On the unmodified (111) surface, CO adsorbsfirst in top site, thenin bridge. Changing the geometry of thesurface to the (110) results in the vanishing of the bridgesite population. Modifying these surfaces by Sn does not changethe CO adsorption site.</p><p>Finally, 2-butenal (CH₃-CH=CH-CH=O) has been adsorbed at 100 K on thePt(111) surface and the Sn/Pt(111) surface alloys. On theunmodified Pt surface, comparison with results obtained forpropene (CH₂=CH-CH₃) adsorption evidences the involvement of the C=Cgroup of the 2-butenal molecule in the bonding to the Ptsurface. The carbonyl group is also suggested to take part inthe bonding, through a σ_ccη₁(O) configuration. This carbonyl group bondingdisappears when Sn is alloyed to the surface, and the formationof a new physisorbed phase is detected.</p>

Thesis (M. Sc.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 286-290).

Thesis (M. Soc. Sc.)--University of Hong Kong, 1984.