Intramolecular hydrogen bonding

Publications which have suggested the participation of hydrogen 2p orbitals in hydrogen bonds and bonds to hydrogen are cited. Particular reference is made to intramolecular hydrogen bonds in conjugated carbonyl compounds. A simple method of incorporating these hydrogen bonds into the framework of the Hückel molecular orbital method is investigated through the relation-ship of calculated bond order to stretching frequency for free and hydrogen bonded carbonyl groups.