Selective chemical vapor deposition (CVD) on metals in the presence of SiO2 can be achieved by passivating the SiO2 surface using reagents which replace or shield isolated hydroxyl, hydrogen-bonded hydroxyl, and SiO four-member rings with less reactive-SiR(3) groups. This process was studied by FTIR of (hfac) CuL (where L = VTMS and 2-butyne) adsorption/desorption on unpassivated and passivated SiO2 surfaces with varying surface concentrations of hydroxyl groups and four-member SiO rings. The passivating reagents included monofunctional trimethylchlorosilane (TMSCI), hexamethyldisilazane (HMDS), trimethyldimethylaminosilane (TMDMA), dimethyl-t-butyldimethylaminosilane (DMBDMA), and bifunctional dimethylbis(dimethylamino)silane (DMDMA) species. Effective passivation was obtained by the rapid reaction of DMBDMA with hydroxylated SiO2 surfaces even when exposed to water vapor. High-temperature treatment of SiO2 before passivation led to less effective passivation because a smaller fraction of the SiO2 surface was protected by the passivating reagent. Bifunctional passivating reagents were less effective because the unreacted functional group on the reagent can react with (hfac)CuL species. Various other aspects of the interaction of (hfac)CuL species with SiO2 surfaces and the implications of these results for selective CVD are discussed.