A @P04755@ in which the change in bond directions to a three-coordinate @C00930@ having a pyramidal arrangement of bonds (tripodal arrangement) causes the @C00930@ (@A00412@ of the pyramid) to appear to move to an equivalent position on the other side of the base of the pyramid. If the three @L03518@ to the @C00930@ are different pyramidal @I03146@ interconverts @E02069@.
PAC, 1996, 68, 2193. (Basic terminology of stereochemistry (IUPAC Recommendations 1996)) on page 2215 [Terms] [Paper]