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.

Le dioxyde de carbone occupe une place particulière dans l'amplification anthropogénique de l'effet de serre. En particulier, son utilisation dans la synthèse de carbonates organiques à partir d'alcools constituerait une alternative à l'emploi actuel du phosgène ou du monoxyde de carbone. L'insertion de CO2 dans Sn-OCH3 liaison de dialkyldimethoxystannanes est reconnue comme la première étape pour la formation du carbonate de diméthyle (DMC) à partir du méthanol et CO2. L'identification des étapes ultérieures est cruciale pour améliorer l'activité et est encore l’objet de débats car les espèces étain ont la propension à l’oligomérisation. Nous avons utilisé des calculs basés sur la Théorie de la Fonctionnelle de la Densité pour donner un aperçu sur le mécanisme de réaction. L'insertion de CO2 est promue par l’interaction acide-base concertée de Lewis de CO2 avec l'étain et l'atome d'oxygène du ligand méthoxy. Le chemin principal de la réaction pour la formation de DMC est proposé selon un réarrangement intramoléculaire des espèces monomériques, Me2Sn[OC(O)OCH3]2. Le processus conduit à un transfert d'un groupe méthyle d'un carbonate de méthyle à l'autre via un anneau de 4 atomes ou 6 atomes formant un fragment Sn-CO3. Dans une deuxième étape, le méthanol réagit avec un intermédiaire et conduit à la formation de DMC et un complexe de trimère qui peut permettre la régénération des réactifs. Mais un complexe décanucléaire d’étain peut être aussi produit par une réaction latérale. Enfin, un cycle catalytique pour produire le DMC a pu être élaboré. Les calculs DFT sont en accord avec les données expérimentales et permettent une analyse comparative des chemins de réaction / Carbon dioxide occupies a special place in the amplification of the anthropogenic greenhouse effect. In particular, its use in the synthesis of organic carbonates from alcohols, constitute an alternative to the current application of phosgene or carbon monoxide. The insertion of CO2 into the Sn-OCH3 bond of dialkyldimethoxystannanes is recognized as the first step to dimethyl carbonate (DMC) formation from methanol and carbon dioxide. The identification of the subsequent steps is crucial for activity improvements and is still under debate as the tin species have the propensity for oligomerization. We have used density functional theory calculations to provide insight into the reaction mechanism. The CO2 insertion into the Sn-OCH3 bond is promoted by the concerted Lewis acid-base interaction of CO2 with tin and the oxygen atom of the methoxy ligand. The major reaction pathway to DMC is proposed to occur via an intramolecular rearrangement of the monomeric species, Me2Sn[OC(O)OCH3]2. The process results in the transfer of a methyl group from one methyl carbonate to the other via a 4-membered or 6-membered ring forming the Sn-CO3 moiety. In a second stage, methanol reacts with one intermediate and leads to DMC formation and a trimer compound which may allow the regeneration of the reactant. Also a decanuclear tin complex is produced due to the lateral reaction. Finally a catalytic cycle for DMC production in methanol can be elaborated. DFT calculations are in agreement with the experimental data and allow a comparative analysis of reaction channels

In order to produce alternative fuels derived from renewable resources (biomass) and environmentally friendly, it was investigated in this work the catalytic activity of three metal complexes showing Lewis acid character: Butyltin chloride dihydroxide (BCDH-Sn), Butyltintrichloride (BTC-Sn) and dibutyltin dichloride (DBDC-Sn).These complexes were tested for catalytic soybean oil methanolysis and esterification of oleic acid in order to obtain a mixture of Fatty Acid Alkyl-Esters, when it is used as a fuel known as biodiesel. In methanolysis experiments, the reactions were performed in a glass reactor equipped with a reflux condenser or a closed reactor. The reactions were performed at temperatures ranging from 80 ° C, 120 ° C and 150 ° C, and the reaction time ranged from 15 minutes to 10 hours. The reaction products, obtained by transesterification, were analyzed by gas chromatography with flame ionization detector (GC-FID). In case of esterification of the oleic acid, was subjected to the same conditions of methanolysis using only the closed reactor. In this case, monoester analysis content was determined by acid-base titration. For characterization of catalysts, spectroscopic techniques were used in infrared and nuclear magnetic resonance. To determine reaction mechanism (trans) esterification, a set of reactions were made with subsequent NMR study 1H and 119Sn. In transesterification, the sequence in terms of catalytic efficiency was: BTC-Sn>BCDHSn>DBDC-Sn. In the esterification, the sequence was: BTC- Sn> DBDC -Sn>BCDHSn. These reactive differences were attributed to factors such as steric hindrance, catalyst solubility in reaction environment, interactions between the catalyst and substrate reaction and the acid strength of the catalysts. RMN's results of 1H and 119Sn indicated that the reactions of transesterification and esterification using three organometallic complexes of tin occur through Lewis´s acid-base mechanism. / No intuito de produzir combustíveis alternativos oriundos de recursos renováveis (biomassa) e ambientalmente corretos, foi investigada neste trabalho a atividade catalítica de três complexos organometálicos exibindo caráter ácido de Lewis: n-butilclorodihidróxiestanho (BCDH-Sn), nbutiltricloroestanho (BTC-Sn) e di n-butildicloroestanho (DBDC-Sn). Esses complexos foram testados na metanólise do óleo de soja e na esterificação do ácido oléico visando obtenção de uma mistura de ésteres alquílicos de ácidos graxos (biodiesel). Nos experimentos de metanólise, as reações foram realizadas em um reator de vidro acoplado a um condensador de refluxo ou num reator fechado. As reações foram realizadas em temperaturas de 80 °C, 120 ºC e 150 °C, e o tempo reacional variou de 15 min a 10 h. Os produtos reacionais, obtidos por transesterificação, foram analisados por cromatografia gasosa com detector de ionização de chama (CG-FID). No caso da esterificação do ácido oléico, foram empregadas as mesmas condições da metanólise empregando apenas reator fechado. Nesse caso, a análise do teor de monoéster foi determinada por titulação ácido-base. Para caracterização dos complexos, foram usadas técnicas de espectroscopia no infravermelho e ressonância magnética nuclear de hidrogênio. A fim de estabelecer o mecanismo reacional de transesterificação e esterificação, foi realizado um conjunto de reações com acompanhamento por espectroscopia de RMN de 1H e 119Sn. Na transesterificação, a seqüência em termos de eficiência catalítica foi: BTC-Sn>BCDH-Sn>DBDC-Sn. Já na esterificação, a seqüência foi: BTC-Sn>DBDC-Sn>BCDH-Sn. Essas diferenças reacionais foram atribuídas a fatores como impedimento estéreo, solubilidade do catalisador no meio reacional, interações entre o catalisador e o substrato na reação e força ácida dos catalisadores. Resultados de RMN´s de 1H e 119Sn indicaram que as reações de transesterificação e esterificação usando os 3 complexos organometálicos de estanho ocorrem através de mecanismo ácido-base de Lewis.