THE CRYSTAL-STRUCTURE AND SPECTRA OF [BIS(DIANILINO-1,2-ETHANE) (TRIFLUOROACETYLACETONATO)NICKEL(II)] PERCHLORATE

The title compound is monoclinic, space group P2(1)/c, Z = 4. Cell dim ensions are a = 12.644(2) Angstrom, b = 14.905(3) Angstrom, c = 17.945 (3) Angstrom and beta = 95.68 degrees(14). total of 5829 reflections w ere measured with a PC-computer-controlled PHILIPS PW1100 automatic di ffractometer using MoK alpha radiation. The structure was refined by f ull-matrix least squares to a conventional R = 0.0668 for 4359 observe d reflections. The charge of the [Ni(enR)(2)tfac](+) entity is counter balanced electrostatically by the perchlorate anion. The nickel(II) io n is six-coordinated and it is positioned at the centre of a nearly re gular octahedron. The best (equatorial) plane encompasses the beta-dio nato metallocyclic ring and one nitrogen of each of the bidentate diam ino ligands. The other donor atoms occupy the remaining apical positio ns and are equidistant from the metal centre. The Ni-O bond lengths ar e virtually identical (average Ni-O 2.006 Angstrom) despite the proxim ity of the strongly electron-attracting trifluoromethyl group to one o f the oxygens. The 1,2-diamine forms five-membered chelate rings, adop ts the gauche conformation and the meso form in accordance with the ap pearance of a double band in the infrared absorption spectrum attribut able to the N-H stretching vibrations. The N-C distances connecting th e phenyl groups are on average shorter by 0.05 Angstrom than those wit hin the chelate rings. The perchlorate group, [ClO4](-), exhibits a di storted tetrahedral structure that causes splitting in the relevant in frared absorption band at similar to 1900 cm(-1).