Few studies have been conducted on heterocyclic systems containing phosphorus.  This is most likely due to the existence of various forms of phosphorus and because molecular structure data and their interconversions are not completely understood.  In this study,  the conventional strain energies of 1,2-oxaphosphetane, 1,3-oxaphosphetane, 1,2,3-oxadiphosphetane, and 1,2,4-oxadiphosphetane are determined within the isodesmic, homodesmotic, and hyperhomodesmotic models.  Optimum equilibrium geometries, harmonic vibrational frequencies, and corresponding electronic energies and zero-point vibrational energies are computed for all pertinent molecular systems using SCF theory, second-order perturbation theory, 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 Truhlar and Zhao. The basis sets employed are Dunning and coworkers’ correlation consistent basis sets: cc-pVDZ, cc-pVTZ, and cc-pVQZ.  In addition, cc-pV(D+d)Z, cc-pV(T+d)Z, and cc-pV(Q+d)Z basis sets are also investigated to determine the effect of the extra d function for phosphorus on the overall results.  Coupled-cluster theory calculations were also performed at MP2/cc-pVTZ and MP2/cc-pVQZ optimum geometries including single and double excitations (CCSD) and CCSD with the inclusion of noniterative, linear triple excitations [CCSD(T)].  The computed conventional strain energies are compared to those of small cyclic hydrocarbons and to other heterocyclic systems.  We gratefully acknowledge support from the NSF (EPS-0903787) and from the Mississippi College Catalysts, the alumni support group of the Department of Chemistry & Biochemistry.  <br/>

Conventional strain energies of the oxaphosphetanes and the oxadiphosphetanes

253rd National Meeting (2017)

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