half-chair 

https://doi.org/10.1351/goldbook.H02715
The @C01258@ of a six-membered ring structure in which four contiguous atoms are in a plane and the other two atoms lie on opposite sides of the plane.
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See also: chair, boat, twist
Source:
PAC, 1996, 68, 2193. (Basic terminology of stereochemistry (IUPAC Recommendations 1996)) on page 2209 [Terms] [Paper]
Citation: 'half-chair' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.H02715 RIS BibTex EndNote
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