Ca 2 [BN 2 ]H: The First Nitridoborate Hydride — Synthesis, Crystal Structure, and Vibrational Spectra

Ca 2 [BN 2 ]H was synthesized from a mixture of the binary components Ca 3 N 2 , CaH 2 and BN (molar ratio 1 : 1 : 2) in a sealed steel ampoule encapsulated in an evacuated silica tube at 1273 K. Ca 2 [BN 2 ]H crystallizes in the orthorhombic space group Pnma (no. 62) with a = 9.2015(8)Å, b = 3.6676(2)Å and c = 9.9874(12)Å ( Z = 4; Pearson symbol oP 24). The crystal structure is a filled variant of the Co 2 P type and can be formulated as Co 2 P(□ t ) 3 (□ py ) 3 ≡ Ca 2 [N—B—N]H(□ t ) 2 (□ py ) 3 (□ t and □ py = tetrahedral and square‐pyramidal hole, respectively). The d (B—N) bond lengths and bond angle for the linear [N—B—N] 3— anion are: d (B—N1) = 1.324(3)Å, d (B—N2) = 1.350(2)Å and ∠N—B—N = 177.2(2)°. The vibrational spectra of Ca 2 [BN 2 ]H confirm the presence of [N—B—N] 3— groups deviating only slightly from the ideal D ∞ h symmetry. The vibrational frequencies and the ƒ(B—N) force constants are discussed and compared with those of the isotypic compound Ca 2 [BN 2 ]F.