The @C01058@ of a helical, propeller or screw-shaped molecular entity. A right-handed @H02769@ is described as P (or plus), a left-handed one as M (or minus).
The application of this system to the description of conformations considers the @T06406@ between two specified (fiducial) groups that are attached to the atoms linked by that bond. The sign of the smaller @T06406@ between the fiducial groups defines the @C01063@ of the @H02769@. Rules for the selection of fiducial groups according to @P04854@ are given by R.S. Cahn, C.K. Ingold and V. Prelog, Angew. Chem. 78, 413-447 (1966), Angew. Chem. Internat. Ed. Eng. 5, 385-415, 511 (1966).
See also:
axial chirality
Δ (delta), Λ (lambda)
PAC, 1996, 68, 2193. (Basic terminology of stereochemistry (IUPAC Recommendations 1996)) on page 2209 [Terms] [Paper]