A Simple Route to Calcium and Strontium Hydride Clusters

Abstract

Abstract The first strontium hydride complex has been obtained by simply treating Sr[N(SiMe 3 ) 2 ] 2 with PhSiH 3 in the presence of PMDTA. The Sr complex Sr 6 H 9 [N(SiMe 3 ) 2 ] 3 ⋅(PMDTA) 3 crystallizes as an “inverse cryptand”: an interstitial H − is surrounded by a Sr 6 H 8 4+ cage decorated with amide and PMDTA ligands. The analogous Ca complex could also be obtained and both retain their solid‐state structures in solution: 1 H NMR spectra in C 6 D 6 show two doublets and one nonet (4:4:1). Up to 90 °C, no coalescence is observed. The Ca cluster was investigated by DFT calculations and shows atypically low charges on Ca (+1.14) and H (−0.59) which signifies an unexpectedly low ionicity. AIM analysis shows hydride⋅⋅⋅hydride bond paths with considerable electron densities in the bond critical point. The clusters thermally decompose into larger, undefined, metal hydride aggregates.