Synthesis and structural characterization of a new alkaline earth imide: MgCa(NH)2

Abstract

The ternary imide of MgCa(NH)2 has been successfully synthesized for the first time by the mechanochemical reaction of Mg(NH2) 2 and CaH2 at a molar ratio of 1:1. It was found that ca. four H atoms were desorbed per Mg(NH2)2-CaH2 after 72 h of ball milling leaving a solid residue with the chemical composition of MgCa(NH)2. The solid residue exhibits an imide N-H stretching vibration at 3151 cm-1 and a cubic CaNH-like structure. In addition, X-ray Absorption Fine Structure examination at the Ca K-edge indicates that six N atoms occupy the first coordination shell of the Ca center in an anticipated octahedral geometry, and Ca(Mg) atoms occupy the second coordination shell. The distances of Ca-N and Ca-Ca(Mg) in the newly formed MgCa(NH)2 structure calculated by ESDs are 2.46 and 3.47 Å, respectively. © Wiley-VCH Verlag GmbH & Co. KGaA, 2006.