Structures and energetics of complexation of metal ions with ammonia, water, and benzene: A computational study

Abstract

Quantum chemical calculations have been performed at CCSD(T)/def2-TZVP level to investigate the strength and nature of interactions of ammonia (NH3 ), water (H2 O), and benzene (C6 H6 ) with various metal ions and validated with the available experimental results. For all the considered metal ions, a preference for C6 H6 is observed for dicationic ions whereas the monocationic ions prefer to bind with NH3 . Density Functional Theory-Symmetry Adapted Perturbation Theory (DFT-SAPT) analysis has been employed at PBE0AC/def2-TZVP level on these complexes (closed shell), to understand the various energy terms contributing to binding energy (BE). The DFT-SAPT result shows that for the metal ion complexes with H2 O electrostatic component is the major contributor to the BE whereas, for C6 H6 complexes polarization component is dominant, except in the case of alkali metal ion complexes. However, in case of NH3 complexes, electrostatic component is dominant for s-block metal ions, whereas, for the d and p-block metal ion complexes both electrostatic and polarization components are important. The geometry (M(+) -N and M(+) -O distance for NH3 and H2 O complexes respectively, and cation-π distance for C6 H6 complexes) for the alkali and alkaline earth metal ion complexes increases down the group. Natural population analysis performed on NH3 , H2 O, and C6 H6 complexes shows that the charge transfer to metal ions is higher in case of C6 H6 complexes.

How Do Metal Ions Modulate the Rate‐Determining Electron‐Transfer Step in Cytochrome P450 Reactions?

“…These observations and explanation are in agreement with general chemical intuition and literature reports of an increase in the electrostatic contribution to the bindinge nergy in complexeso fa lkali metals and nucleophilesw ith an increase in the corresponding M-N distance. [53] The two metal ions are aligned with two CÀHg roups connecting the heme pyrrole rings on opposite sides of the structure (see Figure S1). The coordination of these metals with aw ater molecule further increases the M-N distances (see Figures S7-S10).…”

Unveiling electrostatic portraits of quinones in reduction and protonation states

“…Especially, the understanding of noncovalent interactions involving metal ion binding is expected to provide valuable insights for structural and functional properties of molecular systems. 44 Particularly, the site of metal cation binding confirms the electron localization in the corresponding region of a molecular system. 40 Molecular electrostatic potential (MESP) is a scalar field, used extensively 38, [45][46][47] in the literature for exploring reactivity patterns of molecules and their noncovalent interactions.…”

Ligation kinetics as a probe for gas-phase ligand field effects: Ligation of atomic transition metal cations with ammonia at room temperature

“…An exploration of orbital splitting based on different symmetries indicated that octahedral ligand field splitting produced a close Table 2. Values for experimental and theoretical binding energies (BE) taken from Sharma et al 19 and the ligand field stabilization energy (LFSE) in relative units of D 0 for atomic transition metal cations and their electronic configurations (see text).…”

“…A very useful survey of both experimental and theoretical binding energies has very recently been reported for first-row atomic transition metal cations ligated with ammonia (see Table 1 in Sharma et al. 19 ). These are included in Table 2 which shows that there is generally good agreement between experiment and theory.…”

“…BE, black circles) binding energies taken from Sharma et al. 19 for the ligation of first row atomic transition metal cations with ammonia. BE: binding energy.…”