AXIAL-EQUATORIAL INTERACTIONS IN CHELATES OF BETA-DIONES - CRYSTAL AND MOLECULAR-STRUCTURE OF BIS(3-NITRO-2,4-PENTANEDIONATO)COPPER(II)

The IR spectrum and the structure of bis(3-nitro-2,4-pentanedionato)co pper(II)], [Cu(O2N-acac)(2)] are reported. The structure was determine d by single crystal X-ray diffraction analysis (triclinic, space group P (1) over bar, Z = 1, a = 5.841(5), b = 7.843(7), c = 8.142(8) Angst rom, alpha = 80.40(7), beta = 74.59(7), gamma = 71.80(7)degrees, R-1 = 0.0335, R-w(2) = 0.0809), The anion of 3-nitro-2,4-pentanedione, in a ddition to the commonly encountered bonds involving the carbonyl oxyge ns, also interacts with adjacent copper centres through one of the oxy gen atoms of the -NO2 group at a distance of 2.609(2) Angstrom and the structure becomes polymeric. The axial interactions in the CuO4O2' ch romophore are partly responsible for the elongation of the in-plane bo nds, This is a rare example of a bis(beta-dionato)copper(II) chelate i n which copper(II) exists in a rhombically distorted octahedral enviro nment. (C) 1998 Elsevier Science S.A.