Influence of heteroelement on dipole and quadrupole moments of a series of three-membered rings containing a second,third, fourth,or fifth-row atom: a theoretical investigation

The influence of heteroelements on the molecular dipole and traceless quadrupole moments of a series of twenty-two three-membered rings (1–22) was theoretically estimated employing levels of theory such as MP2, CCSD, and PBE1PBE in combination with standard Pople’s basis set. To an accurate evaluation of these properties, additional calculations on the optimized geometries were performed using the correlation-consistent cc-pVDZ and aug-cc-pVDZ basis sets on the three mentioned methods. In particular, the dipole and quadrupole moments from MP2 and CCSD approaches are comparable to each other for the studied molecules, while PBE1PBE calculations were significantly deviated compared to MP2 and CCSD levels. High level of theory and large basis sets seemed to be needed to obtain reliable electrical properties in the heterocycles containing heavy atoms. Results demonstrated that the dipole and quadrupole moments are strongly determined by the nature of the heteroatom into ring skeleton, and its magnitude depends on the polarity of C-heteroelement bond. Dipole moment of these molecules 1–22 showed a clear increase with the increase of electronegativity and the atomic size of heteroatom into ring skeleton. Then, high relative dipole moment was found for three-membered rings containing II, IIIA, VIA, and VIIA elements, which is associated to the high polarization of the C-heteroatom bond. A similar behavior was observed for the quadrupole moments of these three-membered rings.