Abstract

This work reports the magnetic index of aromaticity of cyclophosphazene (-PNH) and their halogenated cyclic derivatives: -PNF, -PNCl, -PNBr, -PNI, -PNAt and -PNTs. This index, also known as ring-current strength, is calculated by numerical integration of the magnetically-induced current density vector field which is generated by a perturbing external magnetic field. Due to the presence of heavy atoms in -PNX, important relativistic were expected. Accordingly, all-electron density functional theory (DFT) calculations were carried out using the four-component Dirac-Coulomb (DC) Hamiltonian, including scalar and spin-orbit relativistic effects. The values were also compared with the corresponding spin-free (scalar relativistic) ones. The impact of spin-orbit effects on the ring current strengths of substituted cyclophosphazene (cyclo-P3N3X6) significantly intensifies with the incorporation of X from the sixth and seventh rows of the periodic table. Consequently, accurate quantum chemical formulations must incorporate relativistic effects as described by the Dirac equation. image