SYNTHESES AND SPECTROSCOPIC PROPERTIES OF HALOCADMATES(II) - CRYSTAL AND MOLECULAR-STRUCTURE OF A NEW TRIBROMO[N-BENZYLPIPERAZINIUM]CADMIUM(II) COMPOUND

Compounds of formula [CdX4].(LH2).(H2O) (LH2 = N-benzylpiperazinium dication; X = Cl, Br, 1) and one of formula [CdBr3(LH)] (LH = N-benzylpiperazinium monocation) were prepared and characterized. The crystal structure of the monoprotonated N-benzylpiperazinium tribromocadmate(II) complex was determined by means of X-ray analysis. The [CdBr3.(LH)] salt is triclinic (space group and lattice constants: P1BAR, a = 9.500(3), b = 13.145(7), c = 6.801(1) angstrom, alpha = 103.79(2), beta = 96.24(2), gamma = 96.17(5)-degrees, Z = 2, R = 0.0392, R(W) = 0.0394). Its structure consists of discrete monomeric [CdBr3(LH)] units, in which the coordination polyhedron around the cadmium ion is a distorted tetrahedron. The coordination sphere is comprised of the three anionic bromide ligands and one terminal N atom of the N-benzylpiperazinium monocation. All the compounds were also investigated by means of IR and Raman spectroscopic measurements. The Cd-Br stretching vibrations of the structurally known [CdBr3.(LH)] salt were unambiguously assigned on the basis of calculations performed on its spectra and by comparison with literature data. The Cd-X stretching vibrations of the [CdX4].(LH2).(H2O) compounds, assigned by comparing their spectra with those of the monoprotonated N-benzylpiperazinium tribromocadmate and on the basis of literature data, strongly suggest the presence of discrete [CdX4]2- anions.