SFB 1109/1: Slioxane, Alumoxane und Alumosiloxane als Modelle für Oberflächendefekte in Hydrolyse- und Kondensationsreaktionen (TP A 01)

Subject of the project is to study hydrolysis and condensation processes at strained siloxane, alumoxane and alumosiloxane compounds. The latter can be considered to be model com-pounds for defect structures at silicate or aluminosilicate surfaces. They will be prepared by oxygenation of subvalent silicon, aluminium and aluminium/silicon compounds on using triplet or singlet O2 as well as oxygenation agents such as N2O or acetone peroxide. Conceivable target structures are edge-sharing siloxane and alumosiloxane tetrahedra, Si-O-O-Si peroxo moieties and Al-O-Al linkages. Subsequently, hydrolysis and condensation reactions at the oxygenated species with water and silanols will be investigated. We aim to monitor elementary steps in situ by mass spectrometry (A05) and 1H, 2H, 29Si, 27Al and 17O NMR as well as IR and Raman spectroscopy. Larger assemblies will also be studied by MAS NMR (C01). The investigations will be accompanied by DFT calculations on the structure, on IR and Raman data as well as on NMR chemical shifts of the model compounds (A03). In addition, highly sensitive species will be characterized by Liquid Injection Field Desorption/Ionization (LIFDI) Mass Spectrometry.