The surface structure of copper acetylacetonate [Cu(acac)(2)] on silica has been characterized using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Infrared spectroscopy has been used to determine the nature of the supported complex with regard to whether the complex is present on the surface as a single layer or as multiple layers. The copper acetylacetonate attaches to the silica surface from acetonitrile solution initially as a monolayer, with the subsequent formation of multiple layers as the impregnation solution concentration is increased. The integrated Kubelka-Munk intensities of the supported complexes vary linearly with the concentration of the complex on the support. In the 1700-1300 cm(-1) region, the infrared spectrum of the initial layer of the complex on silica is very similar to that of the complex observed in chloroform and bromoform, indicating that hydrogen bonding is the dominant mode of interaction with the surface. The spectrum of the complex in layers above the initial layer can be obtained by subtraction, and appears remarkably similar to that of crystalline Cu(acac)(2). For species in the initial layer, the absorption intensities of vibrational modes with frequencies of less than 1000 cm(-1) are vanishingly small, while the observed intensities for frequencies above 1200 cm(-1) are comparable to those in the second and third layers.