Vapor Phase Installation of CpCo(CO)2 in MOF-808

Metal-organic frameworks (MOFs) including MOF-808 present an opportunity for vapor phase installation of reactive centers that may serve as uniform sites for precision catalysis. The mechanism of cobalt installation in MOF-808 through atomic layer deposition (ALD) upon CpCo(CO)2 exposure is investigated through in situ FTIR spectroscopy complemented by density functional theory modeling. The role of subsequent H2O exposure in the hydrolysis of carbonyl and cyclopentadienyl ligands to complete the installation is also investigated. In situ FTIR study reveals that upon exposure of CpCo(CO)2 to MOF-808 at 115 °C, a long-lived, stable intermediate is formed that presents carbonyl stretching vibrations similar to the undissociated precursor that are attributed to chemisorbed carbonyl complexes. In MOF-808, the cobalt precursor is initially absorbed near the BTC linker, revealing the importance of non-covalent interactions in the installation process. DFT suggests that subsequent H2O exposure promotes carbonyl elimination but leaves a cyclopentadienyl-capped cobalt that is more stable than the complete hydrolysis product. The calculations are consistent with cobalt installation in MOF-808 using CpCo(CO)2 and H2O at 115 °C and further consistent with a lack of cobalt oxide ALD thin film deposition on planar supports.