10.1021/ja027241m.s003 Mikhail Y. Redko Mikhail Y. Redko Rui H. Huang Rui H. Huang James E. Jackson James E. Jackson James F. Harrison James F. Harrison James L. Dye James L. Dye Barium Azacryptand Sodide, the First Alkalide with an Alkaline Earth Cation, Also Contains a Novel Dimer, (Na<sub>2</sub>)<sup>2-</sup> American Chemical Society 2003 Na 2 NH sodium anions form Alkaline Earth Cation MeNH sodide DSC Barium Azacryptand Sodide 23 Na MAS NMR 2003-01-29 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Barium_Azacryptand_Sodide_the_First_Alkalide_with_an_Alkaline_Earth_Cation_Also_Contains_a_Novel_Dimer_Na_sub_2_sub_sup_2-_sup_/3644745 The first barium sodide, with stoichiometry Ba<sup>2+</sup>(H<sub>5</sub>Azacryptand[2.2.2]<sup>-</sup>)Na<sup>-</sup>·2MeNH<sub>2</sub>, was synthesized by the reaction of Ba, Na, and H<sub>6</sub>Azacryptand[2.2.2] in NH<sub>3</sub>−MeNH<sub>2</sub> solution. It was characterized by X-ray crystallography, <sup>23</sup>Na MAS NMR, hydrogen evolution, DSC, optical spectroscopy, and magnetic susceptibility. This is the first sodide in which the sodium anions form (Na<sub>2</sub>)<sup>2-</sup> dimers. Previous theoretical predictions were verified by a calculation of the potential energy curve for the dimer in the field of the surrounding charges, whose positions were determined from the crystal structure.