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X‐ray Crystal Structure and Characterization in Aqueous Solution of{ N , N ′‐Ethylenebis(pyridoxylaminato)}zinc( II )
Author(s) -
Correia Isabel,
Dornyei Agnes,
Avecilla Fernando,
Kiss Tamás,
Costa Pessoa João
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.200500623
Subject(s) - chemistry , protonation , crystallography , coordination sphere , amine gas treating , ligand (biochemistry) , aqueous solution , crystal structure , deprotonation , pyridine , zinc , molecule , coordination geometry , tetracoordinate , metal , stereochemistry , hydrogen bond , medicinal chemistry , ion , organic chemistry , biochemistry , receptor , computer graphics (images) , computer science , planar
The complexation of Zn II with H 2 Rpyr 2 en [H 2 Rpyr 2 en = N , N ′‐ethylenebis(pyridoxylaminato)] in aqueous solution has been studied by pH potentiometry and 1 H NMR spectroscopy. Complex formation constants are determined and binding modes proposed. Complex formation starts at around pH 4, and several species with a 1:1 ligand‐to‐metal ratio with different protonation states form up to pH 12. Only above pH 10 does a hydrolytic species [ZnLH –1 ] – become important. The crystal and molecular structures of [ZnCl(H 2 Rpyr 2 en)] + Cl – · 1.5H 2 O ( 1 ) have been determined by X‐ray diffraction. The coordination of the H 2 Rpyr 2 en ligand involves the two phenolate‐O and two amine‐N atoms in a distorted square‐pyramidal geometry. The two pyridine‐N atoms are protonated, and a Cl – atom completes the coordination sphere. Upon coordination, both N‐amine atoms of H 2 Rpyr 2 en become stereogenic centres, and in both molecules of the unit cell of 1 one of the N‐amine donors has an ( R )‐configuration, and the other an ( S )‐configuration. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)