On the Composition and Crystal Structure of the New Quaternary Hydride Phase Li₄BN₃H₁₀

X-ray data on single crystals of the quaternary metal hydride near the composition LiB0.33N0.67H2.67, previously identified as “Li3BN2H8”, reveal that its true composition is Li4BN3H10. The structure has body-centered-cubic symmetry [space group I213, cell parameter a = 10.679(1)−10.672(1) Å] and contains an ordered arrangement of BH4- and NH2- anions in the molar ratio 1:3. The borohydride anion has an almost ideal tetrahedral geometry (∠H−B−H ∼ 108−114°), while the amide anion has a nearly tetrahedral bond angle (∠H−N−H ∼ 106°). Three symmetry-independent Li atom sites are surrounded by BH4- and NH2- anions in various distorted tetrahedral configurations, one by two B and two N atoms, another by four N atoms, and the third by one B and three N atoms. The Li configuration around B is nearly tetrahedral, while that around N resembles a distorted saddlelike configuration, similar to those in LiBH4 and LiNH2, respectively.