First-principles studies of complex hydride YMn2H6 and its synthesis from metal hydride YMn2H4.5

First-principles calculations were performed for a complex hydride YMn2H6 to investigate its electronic structure and thermodynamic stability. The results indicated that an Y atom and one of two Mn atoms were ionized as Y3+ and Mn2+, respectively, and another Mn atom bound covalently to H atoms to form a [MnH6]5− complex anion. Based on the enthalpy change of −65 kJ/mol estimated from the calculation, we experimentally verified a possible low-pressure synthesis of YMn2H6 from a metal hydride YMn2H4.5. X-ray diffractometry confirmed the formation of YMn2H6 after hydrogenation below 5 MPa, much lower than the previously reported value of 170 MPa.