“…The Al 3+ cation is linked via BH 2 edges and hence adopts a distorted tetrahedral coordination made up of borohydride groups, while the AlH 8 polyhedron has the shape of a snub disphenoid, similar to Al in Al(BH 4 ) 3 ·AB or Mg in Mg(BH 4 ) 2 . ,, The Al···B distances with the BH 4 – ions are in the narrow range of 2.22–2.24 Å, similar to 2.21–2.23 Å in the two Al(BH 4 ) 3 ·NH 3 BH 3 polymorphs. This distance is nearly identical with the Al···B distances of 2.22–2.26 Å in M[Al(BH 4 ) 4 ] (M = Li + , Na + , K + , NH 4 + , Rb + , Cs + ) and [Ph 3 MeP][Al(BH 4 ) 4 ], where the Al 3+ cation is also coordinated to eight H atoms. − The interatomic Al···B contact involving the MeAB’s BH 3 group is slightly longer (2.34 Å) than the distances to the BH 4 – anions, fully consistent with the elongation in Al(BH 4 ) 3 ·AB (2.31 Å). However, they remain much shorter than the metal–boron distances in metal borohydride–AB complexes, namely, 2.63–2.92 Å in (LiBH 4 ) 2 ·AB, LiBH 4 ·AB, and Ca(BH 4 ) 2 ·(AB) 2 . , Al–H bond distances vary accordingly: for the BH 4 – groups, they range from 1.76(2) to 1.80(2) Å, similar to those in Al-based complex hydrides, − and vary from 1.89(1) to 1.96(1) Å, where the AB’s −BH 3 group is involved …”