Oxime analogs of amino acids and peptides are efficient ligands for NiII ions

Abstract

Oxime derivatives of amino acids, amides, and peptides are very efficient ligands for Ni II ions forming very stable water-soluble complexes. Oxime of amino acids amides forms octahedral and square-planar complexes with the same 4N coordination mode. The spectroscopic and Xray diffraction studies indicate an unusual role for the hydrogen bond in NiH −1 L 2 species, which stabilizes the cis coordination of two ligands in a planar complex. Oxime analogs of natural amino acid can be much more efficient ligands than the parent molecules.

cyclo-Tetrakis(μ-3-acetyl-4-methyl-1H-pyrazole-5-carboxylato-κ4N2,O3:N1,O5)tetrakis[aquacopper(II)] tetradecahydrate

“…The intermetallic separations pyrazolate-bridged Cu II ions is 4.0600 (4) Å which is similar to that seen in the structures reported by Zhang et al, 1996 (4.098 -4.115 Å), while the distance between diagonal copper atoms is 5.0814 (5) Å, which is more longer to that observed in the structures reported by Klingele et al, 2007 (4.7091 5 The coordinated pyrazolate ligand exhibits C-C, C-N, N-N bond lengths which are normal for bridging pyrazolate rings (Sliva et al, 1997;Świątek-Kozłowska et al, 2000;Mokhir et al, 2002). The C-O bond lengths in the deprotonated carboxylic groups differs significantly (1.239 (2) and 1.292 (2) ) which is typical for monodentately coordinated carboxylates (Wörl et al, 2005a,b).…”

“…For the use of asymmetric ligands in the preparation of heterometallic complexes, see: Moroz et al (2010). For related structures, see: Mokhir et al (2002); Sliva et al (1997);Wö rl et al (2005a,b); Ś wią tek- Kozłowska et al (2000). For the preparation of related ligands, see: Sachse et al (2008).…”

1-{3-[1-(Hydroxyimino)ethyl]-4-methyl-1H-pyrazol-5-yl}ethanone

“…The bond lengths and angles within the acetyl and oxime groups are normal and comparable to those in the related structures (Fritsky et al, 1998;Mokhir et al, 2002;Świątek-Kozłowska et al, 2000). The C, N, O atoms of the oxime group exist in the nitroso-form (Mokhir et al, 2002;Sliva et al, 1997).…”

Tris(ethylenediamine)nickel(II) bis[2-cyano-2-(oxidoimino)acetamidato]nickelate(II) monohydrate

“…It consists of the central atom and two doubly deprotonated residues of 2-cyano-2-(oxidoimino)acetamidate coordinated via four N atoms belonging to the deprotonated oxidoimine and oxime groups, providing a slightly distorted square-planar geometry. The ligands are situated in trans positions with respect to each other, while in the case of a related ligand containing the same coordination set [2-(hydroxyimino)propanamide; Sliva, Kowalik-Jankowska et al, 1997], the two molecules of the ligand are situated in cis positions owing to the intramolecular hydrogen bond between the two oxime O atoms. This bond is not observed in the case of 2-cyano-2-(oxidoimino)acetamidate owing to the increased acidity of the oxidoimine group (Sliva, Duda et al, 1997).…”