Term: cis conformation
https://doi.org/10.1351/goldbook.C01088

Definition:
Conformations referring to torsion angles θ (A, B, C, D), where A, B, C, D are main-chain atoms, can be described as: cis or synperiplanar (C); gauche or synclinal (G); anticlinal (A); and trans or antiperiplanar (T), corresponding to torsion angles within ± 30° of, respectively, 0°, ± 120° and ± 180°. The letters shown in parentheses (upper case C, G, A, T) are the recommended abbreviations. The symbols G+, G- (or A+, G-, for example) refer to torsion angles of similar type but opposite known sign, i.e. ~ +60°, ~ -60° (or ~ +120°, -120°). The notation G, G(bar) ; A, A(bar) (and T, T(bar) ; C, C(bar) - whenever the torsion angles are not exactly equal to 180° and 0°, respectively) is reserved for the designation of enantiomorph conformations, i.e. conformations of opposite but unspecified sign. Where necessary, a deviation from the proper value of the torsion angle can be indicated by the sign (~), as in the following examples: G(~); G^+ (~); G^- (~).

Related Terms:
1) conformations (http://doi.org/10.1351/goldbook.C01258).
2) synperiplanar (http://doi.org/10.1351/goldbook.T06406-1).
3) gauche (http://doi.org/10.1351/goldbook.G02593).
4) antiperiplanar (http://doi.org/10.1351/goldbook.T06406-3).
5) synclinal (http://doi.org/10.1351/goldbook.T06406-2).
6) anticlinal (http://doi.org/10.1351/goldbook.T06406-4).
7) trans (http://doi.org/10.1351/goldbook.C01092).
8) enantiomorph (http://doi.org/10.1351/goldbook.E02079).
9) deviation (http://doi.org/10.1351/goldbook.D01650).
10) torsion angle (http://doi.org/10.1351/goldbook.T06406-5).

Source: Purple Book, 1st ed., p. 41 (http://old.iupac.org/publications/books/author/metanomski.html)

Citation: '<i>cis</i> conformation' 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.C01088

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