Theoretical Investigation Of Reaction Mechanism Of Metal Acetylacetonates With Hydrogen

Density functional theory ( DFT) has been employed to survey the liquid-phase reactions of metal acetylacetonates ( ferric acetylacetonate and nickel acetylacetonate) with hydrogen. For the reactions of metal acetylacetonates with molecular and atomic hydrogen, and reactions of cluster of metal atoms with molecular hydrogen, geometries and transition states for all the stationary points involved are fully optimized at Dmol3 in Material Studio and the reaction is analyzed in terms of the topology of potential energy surface. The calculation results revealed that the most important step is the activation of the Fe-O bond in metal acetylacetonates by atomic hydrogen. The atomic hydrogen was first adsorbed by metal atom and then shifted to oxygen atom, acetylacetone molecule was finally formed and broke off from the compound. With the continued rupture of Fe-O bonds, metal atom was finally obtained with the break off of acetylacetone molecules. The other important step of the reactions is the catalysis of metal cluster made up of 3 metal atoms to molecular hydrogen, this mechanism has explained the importance and inevitability of inserting hydrogen gas into the reaction in the experiment: it is for the source of atomic hydrogen. The reactions were first touched off by the atomic hydrogen supplied by 1,2-dodecanediol. Once the reaction began and few metal atoms were obtained, the clusters which were formed by metal atoms would serve as catalyzers in the decomposition of molecular hydrogens. The reaction would be a circular reaction when it was touched off.