Polyhedral aluminosilsesquioxanes: Soluble models for aluminosilicates and zeolites.

摘要

Aluminosilicates and zeolites play many important roles in industry as catalysts, catalyst supports, and ion-exchangers. Despite recent advances in spectroscopic techniques, the insolubility of many of these compounds has made detailed studies difficult. The focus of this research project has been to develop reasonable solution state models for these complexes using polyhedral oligosilsesquioxanes, such as the incompletely-condensed silsesquioxane (C{dollar}sb6{dollar}H{dollar}sb{lcub}11{rcub})sb7{dollar}Si{dollar}sb7{dollar}O{dollar}sb9{dollar}(OH){dollar}sb3{dollar}. The apparent similarity of these silsesquioxanes to the secondary building blocks (SBU's) which comprise a variety of zeolites, such as Linde 4A molecular sieve, and their solubility in most common organic solvents makes them an ideal choice for this purpose.; The initial phase of this project involved the synthesis of an aluminum-containing silsesquioxane. This was accomplished via the reaction of (C{dollar}sb6{dollar}H{dollar}sb{lcub}11{rcub})sb7{dollar}Si{dollar}sb7{dollar}O{dollar}sb9{dollar}(OH){dollar}sb3{dollar} with either AlMe{dollar}sb3{dollar}, Al(OR){dollar}sb3{dollar}, or AlCl{dollar}sb3{dollar}/Et{dollar}sb3{dollar}N. The dimeric species ((C{dollar}sb6{dollar}H{dollar}sb{lcub}11{rcub})sb7{dollar}Si{dollar}sb7{dollar}O{dollar}sb{lcub}12{rcub}{dollar}Al) {dollar}sb2{dollar} that is produced from this reaction is easily cleaved by Lewis bases such as Ph{dollar}sb3{dollar}PO. The anionic aluminosilsesquioxane ((C{dollar}sb6{dollar}H{dollar}sb{lcub}11{rcub})sb7{dollar}Si{dollar}sb7{dollar}O{dollar}sb{lcub}12{rcub}{dollar}AlOSiMe{dollar}sb3{dollar}) {dollar}sp-{dollar} (SbMe{dollar}sb4{dollar}) {dollar}sp+{dollar} can be produced by the reaction of ((C{dollar}sb6{dollar}H{dollar}sb{lcub}11{rcub})sb7{dollar}Si{dollar}sb7{dollar}O{dollar}sb{lcub}12{rcub}{dollar}Al) {dollar}sb2{dollar} with Me{dollar}sb4{dollar}SbOSiMe{dollar}sb3{dollar}. The synthesis of (C{dollar}sb6{dollar}H{dollar}sb{lcub}11{rcub})sb7{dollar}Si{dollar}sb8{dollar}O{dollar}sb{lcub}12{rcub}{dollar}(OSbMe{dollar}sb4{dollar}) allowed the construction of the larger anionic aluminosilsesquioxane ((C{dollar}sb6{dollar}H{dollar}sb{lcub}11{rcub})sb7{dollar}Si{dollar}sb7{dollar}O{dollar}sb{lcub}12{rcub}{dollar}AlOSi{dollar}sb8{dollar}O{dollar}sb {lcub}12{rcub}{dollar}(C{dollar}sb6{dollar}H{dollar}sb{lcub}11{rcub})sb7{dollar}) {dollar}sp-{dollar} (SbMe{dollar}sb4{dollar}) {dollar}sp+{dollar}. The dianionic aluminosilsesquioxane ({dollar}{lcub}{dollar}(C{dollar}sb6{dollar}H{dollar}sb{lcub}11{rcub})sb7{dollar}Si{dollar}sb7{dollar}O{dollar}sb{lcub}12{rcub}{dollar}Al{dollar}{rcub}sb2{dollar}O) {dollar}sp{lcub}2-{rcub}{dollar} (SbMe{dollar}sb4{dollar}) {dollar}sp+{dollar} (PMe{dollar}sb4{dollar}) {dollar}sp+{dollar}, was also synthesized.; The second phase of this project involved the extension of the techniques developed above towards the synthesis of larger, anionic aluminosilsesquioxanes. The above techniques, however, proved ineffective and new methodologies for the functionalization of hydrido- and chloro-silsesquioxanes were developed. For example, the use of hexamethyldistannoxane allowed the functionalization of H{dollar}sb8{dollar}Si{dollar}sb8{dollar}O{dollar}sb{lcub}12{rcub}{dollar} to give (Me{dollar}sb3{dollar}SnO){dollar}sb8{dollar}Si{dollar}sb8{dollar}O{dollar}sb{lcub}12{rcub}{dollar}. This compound was readily converted to (Me{dollar}sb4{dollar}SbO){dollar}sb8{dollar}Si{dollar}sb8{dollar}O{dollar}sb{lcub}12{rcub}{dollar} using Me{dollar}sb4{dollar}SbOSiMe{dollar}sb3{dollar}. Attempts to synthesize larger anionic aluminosilsesquioxanes frameworks using (Me{dollar}sb4{dollar}SbO){dollar}sb8{dollar}Si{dollar}sb8{dollar}O{dollar}sb{lcub}12{rcub}{dollar} were hindered by side-reactions involving water.; The last phase of this project utilized the octa-functional silsesquioxane (Me{dollar}sb3{dollar}SnO){