The Peptide bond n partially positive, A pure double bond between C and O would permit free rotation o partially negative The other extreme would prohibit c-Nbond rotation but would place too great a charge on O and N (c) The true electron density is intermediate. The barrier to C-Nbond rotation of about 88 kI mol is enough to keep the amide group planar.•N partially positive; • O partially negative The Peptide Bond