Ammonia diffusion and proton shrfts III Ca(NH&, Sr(NH3)6. and Ba(NH& IIJVC been studled by Iugh-rcsolurlon pro1011 magnehc resonance Ammonia drffuscs rapldly m UICSC compounds above =I00 K by P hoppmg nlcciunrsni Proton shlfls xc ncglwc zmd very smrdl and are mterprctcd m the bght of rcunt ab ~IIIO calcuhtions on mctJI-rmmon~~ complc\cs The alkaline earth hexaammmcs M(NH3)6, where M =Ca, Sr, or Ba, continue to attract attenuon because of their mtrrgulng structures, molecular motrons, and electronic properues [ 11. The most strrkmg structural feature in these materials IS the adoption by NH, of a nearly planar, dlstorted configuration havmg one short (a.94 A) and two extremely long (z1.39 & N-H drstances [?I relative to that III normal pyramIdal NH3 (I .OO A) [3]. In addition, molecular motions rang from proton tunneling lo classk cal rotatron of NH, to NH, diffusion as the temperature is increased [4,5]. Electromcally, these compounds are of great Interest because they provide rare examples of low-electrondenslty metals m which electron-electron mteractions play a prominent role [6-8]. The most recent evrdence for ttus contention comes from the observation of anomalous magnetic behavror [9]. In particular, the magnetic susceptrblhty of Ca(NH3& is strongly temperature dependent and exhibits a broad mmimum near 120 K and a sharp peak near 10 K. In contrast to Ca(NH3)6, the suscept;bililles of &(NCI,), and Ra(NH,), are d:.magnetic and decrease rapIdly as the temperature IS lowered, with the mass susceptlbihty of Ba(NH$6 * Research supported by a NATO Grant and National Science Foundallon Gnnl No. DMR 79-2 1069. at low temperatures being tl1e largest of any nonsuperconducting metal. If NH, rhffusron Indeed occurs above ~100 K m these compounds, as found m broad-hne proton m.rg