Steric and Electronic Effects on the Structure and Photophysical Properties of Hg(II) Complexes

Abstract

Since many factors influence the coordination around a metal center, steric and electronic effects of the ligands mainly determine the connectivity and, thus, the final arrangement. This is emphasized on Hg(II) centers, which have a zero point stabilization energy and, thus, a flexible coordination environment. Therefore, the unrestricted Hg(II) geometry facilitates the predominance of the ligands during the structural inception. Herein, we synthesized and characterized a series of six Hg(II) complexes with general formula (Hg(Pip) 2 (dPy)) (Pip = piperonylate, dPy = 3phenylpyridine (3-phpy) (1), 4-phenylpyridine (4-phpy) (2), 2,2′bipyridine (2,2′-bipy) (3), 1,10-phenanthroline (1,10-phen) (4), 2,2′:6′,2′-terpyridine (terpy) (5), or di(2-picolyl)amine (dpa) ( 6)). The elucidation of their crystal structures revealed the arrangement of three monomers (3, 5, and 6), one dimer (4), and two coordination polymers (1 and 2) depending on the steric requirements of the dPy and predominance of the ligands. Besides, the study of their photophysical properties in solution supported by TD-DFT calculations enabled us to understand their electronic effects and the influence of the structural arrangement on them.

Small Cyclic Diglycolamides: Tautomerism, Solvent Extraction and Coordination with f-Elements: One Strain to Rule Them All

“…In the absence of steric hindrances at metal-binding centers, the electronic effects in the molecule play a decisive role . To understand the effectiveness of the extractant, it is necessary to estimate the charge density at the binding centers and, in the case of DGAs, at oxygen atoms.…”

“…In the absence of steric hindrances at metal-binding centers, the electronic effects in the molecule play a decisive role. 33 To understand the effectiveness of the extractant, it is necessary to estimate the charge density at the binding centers and, in the case of DGAs, at oxygen atoms. Estimating the charge density of a particular atom is a difficult problem, but there are ways by which one can indirectly estimate the change in the charge density of an atom in a series of compounds.…”

Influence of a series of pyridine ligands on the structure and photophysical properties of Cd(ii) complexes

“…The outer atom angles of dPy were also utilized for the analysis given that differently from the bite angles, they consider the planarity of the ligands and their steric effect in the coordination sphere of the complexes. 57…”

“…The outer atom angles of dPy were also utilized for the analysis given that differently from the bite angles, they consider the planarity of the ligands and their steric effect in the coordination sphere of the complexes. 57 The lowest value of the outer atom angle of py in compound 1 (77.04°) permits the introduction of the carbonyl oxygen atom of ACA into the coordination sphere, promoting the formation of the CP. This behavior agrees with Table 1 Geometry distortion analysis of the Cd(II) cores in 1-5 using S parameter calculated with SHAPE, 38,39 and ata values 40,41…”

Controlling the Formation of Two Concomitant Polymorphs in Hg(II) Coordination Polymers

“…Thus, a combination of them can trigger the assembly of different arrangements. 7,35 In pursuit of extending our knowledge on the structure− property relationship of Hg(II) compounds, 36,37 we have combined Hg(OAc) 2 , 1,3-benzodioxole-5-carboxylic acid (piperonylic acid, HPip) and the free rotational 4,4′-bipyridine ligand (4,4′-bipy). The synthesis performed at 95 °C resulted in two concomitant polymorphs bearing the same zigzag onedimensional (1D) structure and accommodating guest N,Ndimethylformamide (DMF) molecules with general formula {[Hg(Pip) 2 (4,4′-bipy)]•DMF} n (P1A and P1B).…”