QTAIM investigation of a dipyrazol-1-ylmethane derivative and its Zn(II) complexes (ZnLX2, X = Cl, Br or I)

Abstract

Topological analyses of the electron density were performed on the bis(pyrazol-1-yl)methane derivative 9-(4-(di-1H-pyrazol-1-ylmethyl)phenyl)-9H-carbazole (L) and its zinc(II) complexes: ZnLCl2 (1), ZnLBr2 (2) and ZnLI2 (3) using the quantum theory of atoms in molecules (QTAIM) at the B3PW91/6-31g(d) theoretical level. The topological parameters derived from the Bader theory were also analyzed; these are characteristics of Zn-bond cri­tical points and of ring critical points. The calculated structural parameters were the frontier molecular orbital energies, the highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO), hardness (η), softness (S), the absolute electronegativity (χ), the elec­trophilicity index (ω) and the fractions of electrons transferred (ΔN) from ZnLX2 complexes to L. Numerous correlations and dependencies between the energy terms of the symmetry adapted perturbation theory approach (SAPT), geometrical, topological and energetic parameters were detected and are des­cribed.