DFT studies of calcium(II), strontium(II) and barium(II) benzoates with N,N,N′,N′-Tetrakis(2-hydroxyethyl/propyl)ethylenediamine

Abstract

The computational study of some s-block metal nitrobenzoateate complexes: [Ca(THEEN)(H2O)]2+ (1), [Ca(THPEN)(H2O)2]2+ (2), [Sr(THPEN)(H2O)3]2+ (3), [Ba(THPEN)(H2O)2]22+(4), [Ba(THEEN)(H2O)2]22+ (5), (where THEEN (N,N,N′,N'-Tetrakis(2-hydroxyethyl)ethylenediamine) and THPEN (N,N,N′,N'- Tetrakis(2-hydroxypropyl)ethylenediamine) are tetrapodal ligands) is presented here using density functional theory (DFT) in its hybrid form B3LYP. The geometries of the title complexes are described by the quantum-chemical approach using input coordinates obtained from the previously synthesized and X-ray characterized diffraction data of [Ca(THEEN)(H2O)](DNB)2.H2O, [Ca(THPEN)(H2O)2](DNB)2.H2O [Sr(THPEN)(H2O)3](DNB)2, [Ba(THPEN)(H2O)2]2(DNB)4.2H2O and [Ba(THEEN)(H2O)2]2(ONB)4 (where DNB− is 3,5-dinitrobenzoate anion and ONB− is 2-nitrobenzoate). Only the primary coordination sphere of complexes (1) - (5) is optimized in the gaseous state. The calculation of energy gaps of frontier orbitals (HOMO-LUMO), 13C -NMR shifts and vibrational bands is carried out using B3LYP/6-31G**/LANL2DZ level of theory. The calculated geometric and spectral parameters reproduced the experimental data with well-agreement. HOMO-LUMO energy gap suggest that [Ca(THPEN)(H2O)2]2+ (2) is the most stable (HLG = 6.893 eV) among all the similar previously and presently reported complexes.