Stacked schiff base complexes. The structural characterization of M,N′-ethylenebis(1,1,1-triflouro-2,4-pentanedioneiminato)copper(II0 and N,N′-ethylenebis(1,1,1-triflouro-2,4-hexanedioneiminato)nickel(II), Cu[en(tfpd) 2] and Ni[en(tfhd) 2

Abstract

The crystals and molecular structures of the Schiff base complexes N,N - ́ ethylenebis(1,1,1-triflouro-2,4-pentanedionato)copper(II), Cu[en(tfpd) 2], CuC 12H 12N 2O 2F 6, and N,N - ́ ethynelebis(1,1,1-triflouro-2-4-hexanedioneiminato-nickel(II) Ni[en(tfhd) 2], NiC 14H 16N 2O 2F 6, have been determined from three-dimensional counter X-ray data. The copper complex crystallizes in the monoclinic space group P2 1/c in a cell of dimensions a = 10.665(5), b = 16.131(9), c = 9.050(4) Å, β = 106.43(5)°. Least-squares refinement of the structure has led to a final R factor (on F) of 0.043 using 2351 independent intensities. The nickel complex also crystallizes in space group P2 1/c with a = 11.434(7), b = 17.798(b), c = 8.741(7) Å with β = 110.60(5)°. Least-squares refinement of the structure, based on 1054 independent observations, has led to an R-facto (on F) of 0.073. The coordination geometry around the metal centers in both complexes is distorted square planar, the angle between the two NMO planes being 13.2° in the copper complex and 8.5° in the nickel complex; these results are in contrast with those reported earlier for the nickel analog of the present copper complex, Ni[en(tfpd) 2], in which the geometry was undistorted square planar. The average CuN and CuO bond lengths are 1.939(8) and 1.909(4) Å, respectively, while the corresponding values for the NiN and NiO bonds in Ni[en(tfhd) 2] are 1.843(9) and 1.857(8) Å, respectively. Both complexes form stacks in the crystals, leading to CuCu and NiNi separations of 4.625(2) and 4.395(3) Å, respectively, with associated CuCuCu and NiNiNi angles of 156.14(2) and 167.74(8)°, respectively. The reported EPR spectra of pure and doped complexes of this type are discussed in the light of their structures.