Synthesis and characterization of copper(II) iodo complexes of diethylenetriamine: isolation of an iodo-bridged copper(II) chain

Abstract

The synthesis and characterization of two complexes of the formulation Cu(dien)I 2, Cu(C 4H 13N 3)I 2, are described. The polymeric complex {[Cu(C 4H 13N 3)I]I} n crystallizes in the orthorhombic space group Pnm2 1 with two molecules in a cell of dimensions a=8.873(2), b=8.890(3), c=6.658(1) Å. The structure has been refined to a final R factor of 0.046 based on 596 independent observed intensities. The structure consists of chains of iodide-bridged copper(II) ions along the crystallographic c direction. The coordination geometry about copper is tetragonally-elongated (4+2) octahedral, the equatorial plane consisting of three nitrogen atoms from the dien ligand and one iodide while the axial sites are occupied by the other (chain-propagating) iodide ligands. The equatorial CuI bond length is 2.585(1) Å while the axial distances are 3.325(1) and 3.371(1) Å. The intrachain CuCu separation is 6.658(1) Å, the c axis length, and the bridging CuI(2)Cu angle is 167.7(1)°. The magnetic susceptibility data for the polymeric complex reveal antiferromagnetic coupling. The monomeric complex [Cu(dien)I 2] crystallizes in the monoclinic space group P2 1/ a with four molecules in a cell of dimensions a=15.140(4), b=9.690(4), c=7.526(2) Å, β=105.95(2)°. The structure has been refined to a final R factor of 0.0723 based on 2460 independent observed intensities. The complex is five coordinate, the structure being best described as a distorted trigonal bipyramid in which N(1) and N(3) are axial while N(2), I(1) and I(2) are in the trigonal plane. As is expected for a trigonal bipyramid, copper lies in the trigonal plane. The CuI distances are very different, one being 2.619(2) Å while the other is 3.049(2) Å.