Formation of a Manganese Tricarbonyl on the MgO Surface from Mn2(CO)_(10): Characterization by Infrared, Electron Paramagnetic Resonance, and X-ray Absorption Spectroscopies

摘要

The goal of this work was to prepare structurally well-defined manganese complexes on high-area MgO powder by vapor deposition of Mn2(CO)_(10). The supported species were characterized by infrared (IR), electron paramagnetic resonance (EPR), and X-ray absorption spectroscopies. The results show that when the manganese loading of the sample was 3.0 wt %, most of the Mn2(CO)_(10) was physisorbed, but when the loadings were less, chemisorbed species predominated, being formed by adsorption of Mn2(CO)_(10) on hydroxyl groups on the MgO surface. Treatment of samples containing 1.0 wt % Mn with O2 at room temperature resulted in oxidation of the manganese and the formation of surface species that are well represented as the d~4 complex Mn(CO)3(O_s)3 (where O_s is surface oxygen of MgO), as indicated by IR and extended X-ray absorption fine structure (EXAFS) spectra. The EXAFS data show Mn-C, C≡O, and Mn-O_s bond lengths as 1.90, 1.43, and 1.98 A, respectively.