Lanthanide complex with dihydride

There are relatively few examples of anionic ruthenium hydrido complexes. Thus, several papers have discussed the preparation of the [RuH6]4 ion from Ru, H2 and various lanthanide dihydrides at 800°C.2490,2491 The 99Ru Mossbauer spectra at 4.2 K for various M2[RuH6] (M = Ca, Sr, Eu, Y) are consistent with diamagnetic Ru11 centres.2492... 

Actinides react directly with Hj to form hydrides of different stoichiometries. Thorium forms a tetragonal dihydride, related to the fluorite structure, and a higher hydride, Th Hjj, which has a complex bcc structure. The trihydrides of U and Pa have the bcc 3-W structure, and U also forms a low-T trihydride with a different bcc structure. Hydrides similar to the third group of the lanthanides (see 1.12.4.1), i.e., an fee dihydride and a hexagonal trihydride, are formed by Np through Bk. 

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