Crystal Structure of Two Nickel Complexes with m-Aminophenol-N,N,O-Triacetic Acid, the Effect of Temperature in the Synthesis

Abstract

Two nickel coordination compounds with m-aminophenol-N,N,O-triacetic acid (H3L), (Ni(L)� (H2O)3)2� Ni(H2O)6� 4.3H2 O( 1), and (Ni(L)� H2O)2� Ni(H2O)6 (2), were obtained under similar reaction conditions but at different synthesis temperature. Single crystal X-ray diffraction analysis reveals that both coordination compounds exhibit discrete dimeric entity structures and contain hexaaqua- nickel cations acting as counter-ions. Unit cell data for (1): triclinic, space group P-1, a = 7.9977(16), b = 10.475(2), c = 12.952(3) Aand a = 107.36(3), b = 99.66(3), c = 96.15(3); and for (2): monoclinic, space group P21/c, a = 13.524(3), b = 8.5703(17), c = 13.820(3) Aand b = 95.25(3) .I n (1), O-H_O hydrogen bonds link the complex anions into a dimeric unit. But in (2), the dimeric unit is generated from two Ni centers bridged by two ligands. Extensive hydrogen bond interactions exist in both coordi- nation compounds, and connect the complex anions, hexa- aquanickel cations and/or water molecules, resulting in three-dimensional supramolecular structures. The com- pounds also have been characterized by elemental analysis, powder X-ray diffraction (PXRD), thermogravimetric anal- ysis (TGA), FT-IR and UV-Vis spectra.