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Why are there two possible bond angles for the nitrous acid molecule?

After perusing Wikipedia I found that there are both cis and trans forms of the nitrous acid molecule. I also note that the cis form is sterically hindered. Could this be a reason for the two different bond angles - there are two different geometric isomers and in one case there are larger van der Waals repulsions, which in turn expands the bond angle?

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  • $\begingroup$ Which bond angles are you referring to? $\endgroup$ – LDC3 Apr 20 '14 at 4:43
  • $\begingroup$ Oops. I am referring to the O-N-O bond angle. $\endgroup$ – Dissenter Apr 20 '14 at 16:05
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This ism the microwave structure of nitrous acid, 1971. Your mileage may vary condensed phase.

DOI:10.1039/TF9716702179 (1971)
The structure of cis-nitrous acid is found to be: O—H = 0.982, N—O(H)= 1.392, N—O = 1.185 Å, ∠ NOH = 104.0 and ∠ ONO = 113.6°, and for trans-nitrous acid: O—H = 0.958, N—O(H)= 1.432, N—O = 1.170 Å, ∠ NOH = 102.1 and ∠ ONO = 110.7°.

http://nzc.iap.ac.cn/uploadpdf/Wang_et_al._CSB_2007a.pdf
2007 pape with more recent citations.

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  • $\begingroup$ Also, would you say that hydrogen bonding has to do with the two different structures? I.e. hydrogen bonding between the H and the O in HONO? $\endgroup$ – Dissenter May 8 '14 at 1:49

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