The conventional strain energies for 1,2-dimethylcyclobutadiene, 1,3-dimethylcyclobutadiene, 1,4-dimethylcyclobutadiene, 1,2-dinitrocyclobutadiene, 1,3-dinitrocyclobutadiene, and 1,4-dinitrocyclobutadiene are determined within the isodesmic, homodesmotic, and hyperhomodesmotic models to see if reduction of strain might correlate with the stabilizing effect these different dimethyl and dinitro substitutions have on cyclobutadiene. Optimum equilibrium geometries, harmonic vibrational frequencies, and corresponding electronic energies are computed for all pertinent molecular systems using SCF theory, second-order perturbation theory (MP2), and density functional theory (DFT). The DFT functionals employed are Becke’s three-parameter hybrid functional using the LYP correlation functional and the M06-2X high nonlocality hybrid functional from Thular and Zhao. In addition, single point CCSD(T) calculations employing the cc-pVQZ basis sets are computed using the MP2/cc-pVQZ optimized geometries to ascertain the contribution of higher-order correlation.  The basis sets employed are Dunning and coworkers’ correlation consistent basis sets: cc-pVDZ, cc-pVTZ, and cc-pVQZ.  Finally, computed bond angles are also examined for correlation with the relative stability and the relative strain energies of the different isomers.  We gratefully acknowledge support from the Mississippi College Catalysts, the alumni support group of the Department of Chemistry & Biochemistry.

Conventional strain energies and relative stabilities of the isomers of dimethyl and dinotrocyclobutadiene

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.