Square-pyramidal copper (II) complexes of linear tetradentate edda-type ligands forming six-membered rings. Molecular structures of [Cu(1,3-pdda) (H2O)] and [Cu(eddp) (H2O)] · 3.5H2O

Three square-pyramidal copper(II) complexes containing a linear O-N-N-O-type tetradentate ligand have been prepared and characterized. The ligands used are 1,3-propanediamine-N,N′-diacetate ion (1,3-pdda), ethylenediamine-N,N′-di-3-propionate ion (eddp) and 1,3-propanediamine-N,N′-di-3-propionate ion (1,3-pddp). In the three compounds a water molecule is in the axial position while the four atoms of ligand are in the basal plane. A five-coordinate, square-pyramidal geometry has been established crystallographically for the complexes [Cu(1,3-pdda)(H2O)] (1) (orthorhombic, Pnma, a = 8.937(4), b = 11.770(5), c = 10.269(5) Å3, V = 1080.2(8) Å3, Z = 4 and R = 0.0699) and [Cu(eddp)(H2O)] · 3.5H2O(2) (monoclinic, C2/c, a = 24.430(8), b = 12.195(3), c = 10.514(2) Å, β = 110.92(2) V = 2926(1) Å3, Z = 8 and R = 0.0515). The Cu(II) ions of these structures are lifted out of plane of the four in-plane ligand atoms by distances ρ = 0.182(5) and 0.154(1) Å, respectively. The six-membered diamine ring of complex 1 assumes the stable chair conformation. The other rings of chelates have expected conformations. The structural data correlating the square-pyramidal stereochemistry are discussed in relation to those obtained for similar complexes. The IR and electronic absorption spectra of [Cu(edda-type) (H2O)] complexes are discussed in comparison with those of related complexes of known geometries. The magnetic measurements are also reported for the complexes studied. © 1998 Elsevier Science S.A.