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Copper( II ) Complexes of the Tetraazamacrocyclic Tertiary Amide Ligand Alanyl‐Cyclam
Author(s) -
Schickaneder Christian,
Heinemann Frank W.,
Alsfasser Ralf
Publication year - 2006
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200600055
Subject(s) - cyclam , chemistry , amide , electrophile , ligand (biochemistry) , stereochemistry , hydrogen bond , metal , crystallography , medicinal chemistry , molecule , organic chemistry , receptor , biochemistry , catalysis
Abstract Hydrogen bonding to the electrically neutral tertiary carboxamide nitrogen atom of peptidyl‐prolyl groups is known to facilitate the C–N bond rotation during peptide and protein folding. Since metal complexes with nitrogen‐coordinated tertiary amide ligands are formally analogous, they may be used to model this so‐called electrophilic activation. In this paper we report on the synthesis of a monoacylated cyclam complex, [(Boc‐Ala‐cyclam)Cu](CF 3 SO 3 ) 2 ( 8 ; Boc: tert ‐butyloxycarbonyl, Ala: alanine, cyclam: 1,4,8,11‐tetraazacyclotetradecane). It contains a fully sp 3 ‐hybridized metal‐bound amide nitrogen atom. The resonance is completely cancelled and the observed C–N distance of 147 pm is consistent with a single bond. These features are exceptional among Werner‐type complexes and define the maximal possible electrophilic distortion of an amide bond.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)