US EPA

1538087 

Journal Article 

Isotype 1D polymers of cobalt(II) or zinc(II) constructed with square-planar tetraaqua-metal(2+) units and the bis-zwitterionic form of the mu(2)-O,O '-trans-1,4-dihydrogen-cyclohexanediaminotetraacetate(2-) ligand 

El Bakkali, H; Choquesillo-Lazarte, D; Dominguez-Martin, A; Brandi-Blanco, M; Castineiras, A; Niclos-Gutierrez, J 

2012 

1 

Polyhedron
ISSN: 02775387 

31 

1 

463-471 

10.1016/j.poly.2011.09.037 

WOS:000300642900060 

An uncompleted reaction between equimolar amounts of Co2CO3(OH)(2)center dot 2H(2)O and trans-1,4-H(4)cyclohexanediaminotetraacetic acid in water affords the 'acid' complex {[Co-II(trans-1,4-H(2)CDTA)(H2O)4]center dot 6H(2)O}(n) (1). Its IR spectrum does not show the expected nu(C=O) band of carboxylic groups. Reactions in aqueous solution between Na(trans-1,4-H(3)CDTA) and Zn(AcO)(2)center dot 2H(2)O or Na-2(trans-1,4-H(2)CDTA) and Zn(NO3)(2)center dot 6H(2)O yield {[Zn(trans-1,4-H(2)CDTA)( H2O)(4)]center dot 6H(2)O}(n) (2) and {[Zn-2(trans-1.4-CDTA)(H2O)(2)]center dot H2O}(n) (3) respectively. Crystal structures of compounds 1-3 and that of the trans-1,4-H(4)CDTA center dot 2H(2)O acid are reported. For steric reasons, in the four reported structures the 1,4-CDTA ligand has the two iminodiacetate moieties as equatorial groups in the 1,4-cyclohexanedi-yl chair. Compounds 1 and 2 are isotype 10 polymers constructed by square planar M-II(H2O)(4)(2+) knots (M-II = Co-II or Zn-II) linked to bis-zwitterionic trans-1,4-H(2)CDTA(2-) ligands that play a typical mu(2)-O,O'-dicarboxylate bridging role. These 1D polymeric structures seem to be favoured by the H-bonded intra-stabilization of the bis-zwitterionic trans-1,4-H2CDTA2- ligand. In the neutral complex (3), the trans-1,4-CDTA acts as a bridging bis-chelating ligand as well as a syn-anti carboxylate building a polymer where the zinc(II) centres exhibit a rough bipyramidal trigonal coordination. (C) 2011 Elsevier Ltd. All rights reserved. 

Crystal structure; Coordination; Polymer; Cobalt(II); Zinc(II); Amino-polycarboxylate