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

Abstract

The oxorhenium(V) complexes [Re (V)O(L A)Cl 2] bearing the (N-2-pyridylmethyl) of l-valine (HL A (1)), l-leucine (HL A (2)), and l-phenylalanine (HL A (3)) and [Re (V)O(L B)Cl] containing the {(N-2pyridylmethyl)-(N-(5-nitro-2-hydroxybenzyl)} of l-valine (H 2L B (1)), l-leucine (H 2L B (2)), and l-phenylalanine (H 2L B (3)) 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 ( (1)H, (13)C, and circular dichroism spectra). Gas-phase geometry optimization and the electronic structures of [Re (V)O(L A (1))Cl 2], [Re (V)O(L A (2))Cl 2], and [Re (V)O(L B (2))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 ( (1)H and (13)C) as well as (1)H- (1)H spin-spin coupling constant were also computed by the gauge-independent atomic orbital method, and the computed values are consistent with the experimental data.

Absolute structural elucidation of natural products—A focus on quantum‐mechanical calculations of solid‐state CD spectra

“…At the present time, the method still looks not fully exploited in the literature, but further applications are expected in the future. In fact, it is common to find situations where chiral compounds with complex structure have been characterized by X‐ray crystal analysis, but their configuration has been assigned by TDDFT calculations on DFT‐optimized structures with the aim to reproduce solution CD spectra, requiring consideration of several minima and/or inclusion of time‐consuming solvent models 129, 139…”

“…In this case too, observed accuracies are very high at a limited computational effort,57 which makes now routine the prediction of absorption and electronic CD spectra of medium‐sized molecules (≈30 nonhydrogen atoms) 49, 52, 60. In fact, the last decade has seen an increasing number of publications concerning TDDFT CD calculations, only the most recent of which (not directly related to the solid state) are given in the bibliography 123, 128–152. Apart from the limitation put by the molecular size, the scope of TDDFT calculations is practically unlimited, still some pitfalls are known.…”

Effect of coordination sphere of the copper center and Cu―Cu distance on catechol oxidase and nuclease activities of the copper complexes

“…Ligands L 1 –L 6 were known; they were characterized by comparing their proton NMR spectra (see supporting information) with those found in the literature …”

“…In this article, we designed and synthesized six Cu(II) complexes with N ‐(2‐pyridylmethyl)‐amino acids, N ‐(2‐pyridylmethyl)‐amino ethanol and their derivatives as ligands (Fig. S1, supporting information) to understand the effect of intermetallic distance and complex structure on their catechol oxidase and nuclease activities.…”

Manganese, technetium and rhenium

“…77 DFT investigations have also been carried out on chiral oxorhenium(V) complexes containing a range of amino acid-derived polydentate ligands to probe their structures and spectroscopic properties. 78 Quantum chemical studies of [PW 11 O 39 (ReN)] nÀ (n = 3-7) have been undertaken to investigate the relationship between the reversible redox properties and the second-order nonlinear optical responses of the complexes. 79 Meanwhile, computational analysis has been used to examine cluster carbonyls of the [Re 6 (m 3 -Se) 8 ] 2+ core.…”