Crystal structure solution of KMg(ND)(ND2): An ordered mixed amide/imide compound

• A new amide/imide phase of potassium–magnesium cations was prepared by ball milling.
• Neutron powder diffraction pattern was employed to solve the crystal structure.
• K cations adopt a heptahedral coordination environment by imide and amide groups.
• Channels and cavities can promote gas diffusion and gas-matter exchange paths.

An ordered mixed deuterated amide/imide potassium–magnesium compound was synthesized with the intent of solving its structure using neutron diffraction technique with help of “ab-initio” methods. Obtained powder diffraction patterns were compatible with the orthorhombic P212121 space group, and lattice parameters a = 9.8896(3) Å; b = 9.3496(3) Å; c = 3.6630(1) Å, respectively.Assuming a density of 1.91 g/cm3 the investigation has allowed to locate the four constituting elements distributed in seven different sites into Wyckoff general positions 4(a), for a total of 28 atoms in the unit cell. This is the first example of crystal structure solution of a mixed imide/amide compound appearing during the dehydrogenation process of a potassium containing amide based hydrogen storage material.

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