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Ru II Complexes Incorporating Tetrathiamacrocycles: Synthesis and Conformational Analysis
Author(s) -
Adams Harry,
Amado A. M.,
Félix Vitor,
Mann Brian E.,
AnteloMartinez Jorge,
Newell Mike,
RibeiroClaro Paulo J. A.,
Spey Sharon E.,
Thomas James A.
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400693
Subject(s) - steric effects , chemistry , intramolecular force , lone pair , crystallography , octahedron , pyridine , nuclear magnetic resonance spectroscopy , electronic effect , ligand (biochemistry) , stereochemistry , proton nmr , molecule , crystal structure , biochemistry , receptor , organic chemistry , medicinal chemistry
The synthesis of a series of Ru II complexes incorporating thiacrown ligands ([12]ane‐S 4 , [14]ane‐S 4 , [16]ane‐S 4 ), as well as 2,2′‐bipyridine (bpy) or pyridine, is reported. Structural studies on these complexes have been carried out using a variety of techniques. Detailed 1 H NMR spectroscopic studies on the previously reported [Ru([12]ane‐S 4 )(bpy)] 2+ ( 1 ) reveal that—contrary to earlier reports—the observed fluxional 1 H NMR behavior is not due to chemical exchange involving cleavage of the bpy RuN bond but is, in fact, due to lone‐pair inversion of coordinated macrocyclic sulfur donor atoms. This phenomenon is also observed for the [14]ane‐S 4 and [16]ane‐S 4 analogues of 1 . For the first time, using a combination of X‐ray crystallography, more detailed 1 H NMR experiments, and computational methods, an in‐depth study on the energetics and dynamics of invertomer formation and conversion for macrocyclic coordination complexes has been carried out. These studies reveal that the steric constraints of assembling each sulfur macrocycle and bpy ligand around the octahedral Ru II center lead to close intramolecular contacts. These contacts are largely dependent on the orientation of the electron lone pairs of equatorial sulfur donor atoms and correlate with the comparative stability of the different invertomeric forms. Thus, the conformational preferences of the three macrocyles in [Ru([ n ]ane‐S 4 )(bpy)] 2+ complexes are determined by steric rather than electronic effects.