Shown opposite is an interesting structure consisting of alternating sheets of hexagonal ice and cubic ice, which was first described here in 2000. This structure is now thought to play a significant part in cubic ice structures, where mixed hexagonal and cubic ice planes are often found [1236] and the ice is called stacking disorded ice Isd.
Please note that in all these structural diagrams the hydrogen bonding is ordered whereas, if the structure were to exist, the hydrogen bonding would in all likelihood be random (obeying the 'ice rules': two hydrogen atoms near each oxygen, one hydrogen atom on each O····O bond). Also the stacking disorder would be more random than alternate. The (perfectly ordered) crystal structure appears to be hexagonal with unit cell (8 molecules) dimensions 4.48 Å (a,b) and 14.62 Å (c).
Interactive structures are given (Jmol).
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This page was last updated by Martin Chaplin on 10 April, 2012
