Vanadyl tert-butoxy orthosilicate, OV[OSi((OBu)-Bu-t)(3)](3): A model for isolated vanadlyl sites on silica and a precursor to vanadia-silica xerogels

The single source precursor OV[OSi((OBu)-Bu-t)(3)](3) was synthesized in hi gh yield from OVCl3 and HOSi((OBu)-Bu-t)(3). This tri(alkoxy)siloxy complex was characterized by H-1, C-13, Si-29, and V-51 NMR, FT-Raman, FT-IR, EXAF S, and UV-vis spectroscopies and by mass spectrometry. In the Raman spectru m of OV[OSi((OBu)-Bu-t)(3)](3), V=O (1038 cm(-1)) and V-O (651, 674, and 70 5 cm(-1)) vibrations were observed. The V-51 NMR shift was observed at -777 ppm and the Si-29 NMR resonance appears at -98 ppm. Thermolysis in n-octan e at 180 degrees C resulted in formation of a green gel which upon drying i n air formed a xerogel with a surface area of 320 m(2) g(-1), an average po re size of 140 Angstrom, and a total pore volume of 2.25 cm(3) g(-1). The c alcined xerogel is similar to bulk V2O5 in catalytic performance for propan e oxidative dehydrogenation.