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Hydrogen peroxide has an "open book" structure: structure of H2O2

The dihedral angle in gaseous H$_2$O$_2$ is close to what we might expect in a tetrahedral arrangement. However, in solid H$_2$O$_2$ it's almost a right angle. My book says that this is due to "hydrogen bonding" but doesn't go into further detail.

Note that this question isn't a duplicate of Dihedral angle of gaseous and crystalline HOOH as the accepted answer is clearly incomplete, and the other answer uses a computer simulation that falls short of an intuitive explanation.

Ray Bradbury
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    The intuitive explanation is that the crystal structure forces the molecules into this form. Anything more involved will be heavy on math. – Ivan Neretin Mar 11 '21 at 16:17
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    Well, hydrogen bonding is surely present in the crystal structure, and that's how it is involved. – Ivan Neretin Mar 11 '21 at 16:22
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    Allow this anthropomorphism: In the gas, the isolated molecule is free to venture out each and any conformation most comfortable for the molecule. Over time, it may drop into the energetic pit of least energy. In the solid state, especially the regular crystalline, this optimization about the individual molecule no longer is possible. The lowest energy is met for the molecule including its interactions with its neighbours; you may say, an optimization of the supramolecule. – Buttonwood Mar 11 '21 at 16:30

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