 Another two Al–O bonds roughly in the same plane have a length of 1.89 Å.The other two Al–O bonds complete a distorted octahedral arrangement and pop out the top and bottom of the aluminium with a length of 1.93 Å.The bidentate connected nitrate group is distorted so that the uncoordinated terminal oxygen bond is shorter than the coordinated oxygen–nitrogen distance (1.22 versus 1.31 Å).