Synthetic and structural studies of the trans bis(2-N-H-pyrrolylcarbaldimine) complexes of nickel(II) and palladium(II)

摘要

The molecular bis(2-N-H-pyrrolylcarbaldimine)nickel(II) and palladium(II) complexes are isolated in moderate yield (30-35%) from in situ assembly of the Schiff base with metal(II) salt, base, and pyrrole-2-carbaldehyde in aqueous ammonia solution. The nickel(II) complex, 1, is monoclinic, space group P2(1)/c, with a = 11.289(6) angstrom, b = 5.611(3) angstrom, c = 8.287(5) angstrom, beta = 111.620(6)degrees, and V = 488.0(5) angstrom(3) Z = 2, for d(calc)=1.667 Mg/m(3). The palladium analog, 2, is isomorphous, space group P2(1)/c, with a = 11.481(3) angstrom, b = 5.5738(10) angstrom, c = 8.276(2) angstrom, beta = 110.923(12)degrees, and V = 494.7(2) angstrom(3) with Z = 2, for d(calc) = 1.965 Mg/m(3). In both crystal structures, the metal resides on an inversion center. In the IR spectra, nu(C=N) appears at 1561 cm(-1) in 1, and 1557 cm(-)1 in 2, while nu(N-H) shows at 3345 cm(-1) and 3335 cm(-1), respectively. The H-1-nmr spectra reveal the C-H and N-H protons of the imine group as sharp and broad doublets, respectively, at 7.62 and 8.38 delta in 1 and at 7.92 and 9.73 delta in 2.