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Metal binding studies with macrocyclic hexathioethers: Transition metal complexes of 22S6 and 20S6
Author(s) -
Grant Gregory J.,
Brandow Christopher G.,
Bruce Chrystal Williams,
Bryant Mark A.,
Kirk Rebecca M.,
Lee Sabrina D.,
Rickerd Kerry R.,
Mehne Larry F.
Publication year - 2001
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570380607
Subject(s) - chemistry , solvolysis , metal , transition metal , electrochemistry , ligand (biochemistry) , ring (chemistry) , spectrochemical series , ligand field theory , metal ions in aqueous solution , crystallography , stereochemistry , inorganic chemistry , hydrolysis , ion , computational chemistry , organic chemistry , catalysis , electrode , biochemistry , receptor
Abstract The two macrocyclic hexathioethers, 1,4,7,12,15,18‐hexathiacyclodocosane (22S6) and 1,4,7,11,14,17‐hexathiacycloeicosane (20S6) have been examined with respect to their complexation behavior towards a variety of transition metals ions. In all of these complexes, the two ligands generate relatively strong ligand field, but their field strengths fall between the smaller ring and stronger field hexathioether ligands (such as 18S6) and larger ring and weaker field ligands, such as 24S6. The stability of the complexes towards hydrolysis parallels their reduced field strengths with first row transition metal complexes of both ligands showing enhanced sensitivity to solvolysis reactions compared to the analogous 18S6 complexes. In general, the electrochemical behavior of the hexathioether complexes shows metal centered oxidations which occur at higher potentials than those complexes involving trithioethers. We suggest that the hexathioether ligand is less able to expand and contract during the reduction and oxidation of the metal center. The complex [Pd(22S6)] 2+ does not display the unusual spectroscopic and electrochemical properties observed in the analogous 18S6 complex.