Reactions of Mn with H₂O and MnO with H₂. Matrix-Isolation FTIR and Quantum Chemical Studies

The reactions of Mn atoms with water and MnO with H 2 have been studied using matrix-isolation FTIR and DFT theoretical calculations. In solid argon, Mn atom reacted with H 2 O molecule to form the MnOH 2 complex spontaneously. Photolysis destroyed the MnOH 2 complex and produced the inserted HMnOH molecule. In addition, HMnOMnH, Mn(OH) 2, HMnOMnOH, and posssibly HMnOMnOMnH molecules were also produced on photolysis. Reaction of MnO with H 2 gave the (H 2 )MnO complex without activation energy. Photolysis of the (H 2 )MnO produced the inserted HMnOH molecule as well. The aforementioned species were identified via isotopic substitutions as well as density functional theoretical frequency calculations. Potential energy surface for the Mn + H 2 O ⇔ MnO + H 2 reaction was also given. Our calculation results showed that all these reaction intermediates and products are high spin molecules. The MnOH 2, HMnOH and (H 2 )MnO molecules have ground states with S = 5 / 2, the HMnOMnH, and HMnOMnOH molecules have ground states with S = 10 / 2, and the HMnOMnOMnH molecule has ground state with S = 15 / 2 .