title: Why Are Addition Reactions to N2Thermodynamically Unfavorable?
abstract: Thermochemical data are used to show that, of the 89.9 kcal/mol difference between the endothermicity of H2addition to N2(ΔH = 47.9 kcal/mol) and the exothermicity of H2addition to acetylene (ΔH = -42.0 kcal/mol), less than half is due to a stronger π bond in N2than in acetylene. The other major contributor to the difference of 89.9 kcal/mol between the enthalpies of hydrogenation of N2and acetylene is that the pair of N-H bonds that are created in the addition of H2to N2are significantly weaker than the pair of C-H bonds that are created in the addition of H2to acetylene. The reasons for this large difference between the strengths of the N-H bonds in E-HN═NH and the C-H bonds in H2C═CH2are analyzed and discussed.
authors.affiliation: Department of Chemistry and the Center for Advanced Scientific Computing and Modeling, University of North Texas , 1155 Union Circle, #305070, Denton, Texas 76203-5070, United States.
authors.forename: Weston Thatcher
authors.identifier: http://orcid.org/0000-0003-4782-3381
authors.initials: WT
authors.lastname: Borden