The crystal structure and spectra of [bis(dianilino-1,2-ethane) (trifluoroacetylacetonato)nickel(II)] perchlorate

Abstract

Abstract The title compound is monoclinic, space group P21/c, Z = 4. Cell dimensions are a = 12.644(2) Å, b = 14.905(3) Å, c = 17.945(3) Å and β = 95.68°(14). A total of 5829 reflections were measured with a PC-computer-controlled PHILIPS PW1100 automatic diffractometer using MoKα radiation. The structure was refined by full-matrix least squares to a conventional R = 0.0668 for 4359 observed reflections. The charge of the [Ni(enR)2tfac]+ entity is counterbalanced electro-statically by the perchlorate anion. The nickel(II) ion is six-coordinated and it is positioned at the centre of a nearly regular octahedron. The best (equatorial) plane encompasses the β-dionato metallocyclic ring and one nitrogen of each of the bidentate diamino ligands. The other donor atoms occupy the remaining apical positions and are equidistant from the metal centre. The Ni–O bond lengths are virtually identical (average Ni–O 2.006 Å) despite the proximity of the strongly electron-attracting trifluoromethyl group to one of the oxygens. The 1,2-diamine forms five-membered chelate rings, adopts the gauche conformation and the meso form in accordance with the appearance of a double band in the infrared absorption spectrum attributable to the N–H stretching vibrations. The N–C distances connecting the phenyl groups are on average shorter by 0.05 Å than those within the chelate rings. The perchlorate group, [ClO4]−, exhibits a distorted tetrahedral structure that causes splitting in the relevant infrared absorption band at ∼ 1900 cm−1.