X-ray crystal structures of metalsaccharin complexes of general formula [M(C 7H 4NO 3S) 2(H 2O) 4]·2H 2O, where M = Fe(II), Co(II), Ni(II) and Cu(II)

Abstract

The crystal and molecular structures for the series of complexes, [M(C 7H 4NO 3S) 2(H 2O) 4]·2H 2O (M = Fe, Co, Ni and Cu) have been determined by single-crystal X-ray diffraction methods. The compounds crystallize in the monoclinic space group P2 1/ c with lattice parameters: a = 7.929, b = 16.140, c = 7.738 Å and β = 99.77° (iron complex), a = 7.908, b = 16.136, c = 7.688 Å and β = 99.60° (cobalt complex), a = 7.918, b = 16.139, c = 7.651 Å and β = 99.94° (nickel complex), and a = 8.384, b = 16.327, c = 7.237 Å and β = 101.08° (copper complex). Full-matrix least-squares refinement has given R values of 0.040, 0.029, 0.032 and 0.034 based on 1600, 2556, 2449 and 1339 independent diffractometer data for the iron, cobalt, nickel and copper complexes respectively. The structural parameters in the series are compared and discussed in detail. The hydrogen bonding system in the copper complex is found to be significantly different from that in the other three compounds which form an isostructural series.