Square-pyramidal copper(II) chelate complexes of edta-type and related ligands forming six-membered rings. Crystal structure of magnesium (ethylenediamine-N,N,N '-tri-3-propionato-N '-3-propionate)copper(II) decahydrate, Mg[Cu(edtp)]center dot 10H(2)O

Two square-pyramidal complexes, Mg[Cu(edtp)]. 10H(2)O (1) (edtp = ethylened iamine-N,N,N ' ,N ' -tetra-3-propionate ion, acting as a pentadentate) and Mg[Cu(ed3P)](2). 6H(2)O (2) (ed3p = ethylenediamine-N,N,N ' -tri-3-propiona te ion) have been prepared and characterized. A square-pyramidal geometry w as established crystallographically for the complex Mg[Cu(cdtp)]. 10H(2)O ( 1). The Cu(II) ion in the complex anion is displaced by 0.195 Angstrom from the plane of the four in-plane (2N and 2O) ligand atoms towards the apical oxygen atom of the beta -alaninate (R) ring (Cu-O-ax = 2.173 Angstrom). Th e conformations of the chelate rings are those usually expected for these k inds of chelates (a five-membered diamine (E) ring in a twist(lambda) confo rmation, two beta -alaninate (G(1) and G(2)) rings in a distorted twist-cha ir and one beta -alaninate (R) ring in a distorted twist-boat conformation) . The structural data correlating the square-pyramidal stereochemistry are discussed with reference to those obtained for related complexes. Electroni c absorption and reflectance spectra are discussed in comparison with those of related complexes of known structures. IR data (carboxylate region) are also reported. (C) 2001 Elsevier Science Ltd. All rights reserved.