THE CRYSTAL-STRUCTURE OF [(N,N'-DIPHENYL-1,2-DIAMINOETHANE)-(2,4-PENTANEDIONATO)-(O,O'-NITRATO)NICKEL(II)]

The title compound, [Ni(acac)(Phi en Phi)(O2NO)] C19H23N3NiO5, is monoclinic, space group P2(1)/a, Z = 4 Cell dimensions are a = 13.659(7) Angstrom, b = 12.746(6) Angstrom, c = 13.707(7) Angstrom and beta = 117.71(3)degrees. A total of 3498 reflections were measured with a PC-computer controlled PHILIPS PW 1100 automatic diffractometer using MoK(a)lpha radiation. The structure was refined by full-matrix least squares to a conventional R = 0.038 for 2623 observed reflections with I > 2 sigma(I). The coordination around the central nickel atom is a distorted octahedron with the apices of the octahedron occupied by the oxygen atoms of the acetylacetonato (2,4-pentanedionato) moiety, the nitrogen atoms of the N,N'-diphenyl-1,2-diaminoethane (Phi en Phi) ligand, and two of the oxygens on the nitrate group, [NO3](-). As a result of this coordination a resonance-stabilised six-membered beta-dionato chelate ring, a five-membered chelate ring with the 1,2-diamine ligand in the gauche conformation, and a four-membered cheIate ring are formed, with the NO3- acting as an O,O' chelating ligand. As expected, the bite angle becomes more acute as the ring size diminishes, the actual values being 95.43 degrees, 81.83 degrees, and 59.63 degrees respectively.