Sequential selective formation of adsorbed tert-butoxy and tert-butyl groups from tert-butyl formate on Ni(111)

The sequential preparation of tert-butoxy and tert-butyl groups on Ni(lll) was achieved through the thermal decomposition of adsorbed tert-butyl formate. The two intermediates were characterized using infrared reflection-absorption spectroscopy, XPS, and TPD measurements. The initial step, below 250 K, yielded coadsorbed tert-butoxy, carbon monoxide, and atomic hydrogen. The second step, in the temperature range 310-370 K, produced adsorbed oxygen atoms and surface tert-butyl groups through scission of the tert-butoxy C-O bond. The complete removal of the tert-butoxy groups coincided with the recombinative desorption of hydrogen adatoms derived from the formyl group of the parent molecule. The decomposition of the tert-butyl groups at 410 K coincided with the desorption limited removal of CO from the surface. Quantitative XPS analysis confirmed that the decomposition of tert-butyl formate on Ni(lll) proceeds exclusively through the sequential formation of tert-butoxy and tert-butyl groups.