Talk:Sigma-pi and equivalent-orbital models

Comments

The discussion of the C=C bond (Huckel v. bananas) alongside the H₂O seems perhaps a little odd. The first topic is one that is not discussed in much depth elsewhere. Bent in his book "Molecules and the Chemical Bond" describes the double bond as a banana bond with C having two sp² hybrids forming the C-H bond and two sp5 hybrids overlapping to form the double bond. This better approximates the known HCH bond angle of ca 117.5° than the Pauling description. What I have never seen is a treatment of ethene which accounts for the known HCH bond angle, there must be one. Can the Huckel decription hybridization be tweaked to leave "pure" p orbitals on each C atom? The banana bond model presumably can be tweaked to put a little more p character into the sp² hybrids and a little less in the sp⁵. Bent said that a physical measurement of electron distribution would settle the difference between the unantisymmetrized MO picture with high electron density along the bond axis and the equivalent orbital (banana) description which would predict a low electron density along the bond axis.Axiosaurus (talk) 10:14, 20 April 2015 (UTC)[reply]

Carroll's Perspectives on Structure and Mechanism in Organic Chemistry has a very good discussion how the two models do in terms of predicting bond angles of ethene. Carroll takes an agnostic view of these two models, which he does for many "models" in chemistry, much to the frustration of students who just want the know the "right" answer. Alsosaid1987 (talk) 06:06, 21 February 2019 (UTC)[reply]