Synthesis, Structure, and Spectroscopic Properties of Chiral Oxorhenium(V) Complexes Incorporating Polydentate Ligands Derived from l-Amino Acids: A Density Functional Theory/Time-Dependent Density Functional Theory Investigation

The oxorhenium(V) complexes [ReVO(LA)Cl2] bearing the (N-2-pyridylmethyl) of l-valine (HLA1), l-leucine (HLA2), and l-phenylalanine (HLA3) and [ReVO(LB)Cl] containing the {(N-2pyridylmethyl)-(N-(5-nitro-2-hydroxybenzyl)} of l-valine (H2LB1), l-leucine (H2LB2), and l-phenylalanine (H2LB3) are presented in this article. The complexes are isolated in enantiomeric pure form examined from X-ray structure determination. The complexes are characterized by spectroscopic and electrochemical methods. The molecular structures observed in the solid state are grossly preserved in solution (1H, 13C, and circular dichroism spectra). Gas-phase geometry optimization and the electronic structures of [ReVO(LA1)Cl2], [ReVO(LA2)Cl2], and [ReVO(LB2)Cl] have been investigated with the framework of density functional theory. The absorption and circular dichroism spectra of the complexes were also calculated applying time-dependent density functional theory (TDDFT) using the conductor-like polarizable continuum solvent model to understand the origin of the electronic excitations. The chemical shift (1H and 13C) as well as 1H−1H spin−spin coupling constant were also computed by the gauge-independent atomic orbital method, and the computed values are consistent with the experimental data.