Complexes of 5,5'-aminoacido-substituted 2,2'-bipyridyl ligands: control of diastereoselectivity with a pH switch and a chloride-responsive combinatorial library

Dalton Transactions : an International Journal of Inorganic Chemistry
Shane G TelferAlan F Williams

Abstract

The synthesis and coordination chemistry of a new chiral ligand, 2,2'-bipyridine substituted at the 5 and 5' positions by N-methyl-L-valine methyl ester (5), is presented. The ligand readily forms complexes [M(5)3]2+ where M = Co(II) and Fe(II) in CH3CN, and the complexation reaction is slightly diastereoselective (d.e. =ca. 20%) in favour of the Delta diastereomer. The addition of six equivalents of HCl to these complexes [M(II)(5)3]2+ leads to formation of Delta-[M(II)(5H2)3]8+ with a d.e. of 100%. This high diastereoselectivity can be reversed by the addition of base i.e. the diastereoselectivity can be controlled by the pH. Delta-[Fe(5H2)3]8+ was found to bind chloride ions in CD3OD-CD3CN (6:1) with a binding constant of 260 M(-1). [Co(II)(5)3]2+ can be oxidised to Delta-[Co(III)(5H2)3]9+. Formation constants for both [Co(II)(5)3]2+ and [Co(II)(5H2)3]8+ in acetonitrile were obtained by spectrophotometric titrations. In the former case, the stability constant, log beta3 = 19.5(8), is very similar to that measured for [Co(II)(bipy)3]2+ (log beta3 = 19.3(7)) but this drops significantly when the amine groups of are protonated (log beta3 = 16.5(2)). A dynamic combinatorial library was prepared by mixing three equivalents of, th...Continue Reading

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Citations

Feb 16, 2006·Chemical Communications : Chem Comm·Sheba D BergmanJérôme Lacour
Apr 13, 2006·Chemical Communications : Chem Comm·Marie Hutin, Jonathan Nitschke
May 24, 2006·Chemical Communications : Chem Comm·Almudena González-AlvarezVicente Gotor
Oct 19, 2006·Chemical Communications : Chem Comm·Simon M Turega, Douglas Philp
Oct 15, 2009·Chemical Communications : Chem Comm·Claudia CaltagironeMark E Light
Dec 14, 2004·Angewandte Chemie·Jonathan R NitschkeGérald Bernardinelli
Mar 1, 2006·Dalton Transactions : an International Journal of Inorganic Chemistry·Sandrine Goetz, Paul E Kruger
Mar 10, 2006·Angewandte Chemie·David Schultz, Jonathan R Nitschke
Nov 23, 2012·Organic & Biomolecular Chemistry·Piero Geotti-BianchiniJean-Louis Reymond
Feb 18, 2011·Dalton Transactions : an International Journal of Inorganic Chemistry·Biao WuChristoph Janiak
Apr 10, 2014·Chemistry : a European Journal·Christine KallweitSascha Woitschetzki
Dec 5, 2009·The Journal of Organic Chemistry·A Gastón Orrillo, Ricardo L E Furlan
Aug 13, 2008·Journal of the American Chemical Society·Mee-Kyung ChungMichel R Gagné
Sep 14, 2006·Chemical Reviews·Peter T CorbettSijbren Otto

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