STRUCTURE OF THE CESIUM CUPRIC ETHYLAMINEBIS (METHYLPHOSPHONATE) HEPTAHYDRATE

An x-ray diffraction structural analysis and IR spectroscopic study was carried out on the cesium heptahydrate salt of the cupric complexonate derived from ethylaminebis(methylphosphonic) acid (H-4eadp) with the formula Cs2Cu(eadp).7H2O. The unit cell parameters are as follows: a = 23.826(6), b = 6.343(2), c = 13.434(2) angstrom, beta = 108.46-degrees, space group C2, Z = 4. The structure was determined in the Pl space group and the transition to new parameters was carried out after the least squares refinement. The final R = 0.042. The complexonate crystals consist of chains of complexes, cesium ions, and water of crystallization molecules. The copper coordination polyhedron is a distorted tetragonal pyramid. The nitrogen atom, two oxygen atoms of two phosphonic acid groups of the ligand, forming aminomethylenephosphonic metallocycles fused along the Cu-N line, and an oxygen atom of a phosphonic acid group of the adjacent ligand are found in the equatorial plane of this pyramid. A water molecule is found in the apical position. The structural function of the ligand is tetradentate-bridging. The division of the structural functions of the phosphonic acid groups of the ligand into monodentate and bidentate-bridging leads to an additional displacement of the vdPO3 bands in the IR spectrum of this complexonate.