Solvolthermal Syntheses and Crystal Structures of Three Linear Trinuclear Schiff Base Complexes of Zinc(II) and Cadmium(II)

Abstract

AbstractThree linear trinuclear Schiff base complexes, {Zn[Zn(CH3COO)(C17H16N2O2)]2} (1), {Zn[Zn(CH3COO)(C25H20N2O2)]2} (2), and {Cd[Cd(CH3COO)(C18H18N2O2)]2} (3), were synthesized for the first time under solvolthermal conditions. Their structures have been characterized by elemental analyses, X‐ray single crystal determinations, and infrared spectroscopy. There are three bridges across the M‐M atom pairs (M is Zn for 1 and 2, or Cd for 3) in each complex, involving two O atoms of a Schiff base ligand (N,N′‐bis(salicylidene)‐1, 3‐propanediaminate (SALPD2‐) for 1, N, N′‐bis(2‐hydroxy‐naphthalmethenylimino)‐1, 3‐propanediaminate (NAPTPD2‐) for 2, and N,N′‐bis‐(salicylidene)‐1,4‐butanediaminate (SALBD2‐) for 3), and an O‐C‐O moiety of a μ‐acetato group. In each of the complexes, the central M2+ ion is located on an inversion center and has a distorted octahedral coordination involving four bridging O atoms from two Schiff base ligands in the equatorial plane and one O atom from each bridging acetate group in the axial positions. The coordination around the terminal M2+ ions is irregular square pyramidal, with two O atoms and two N atoms of the Schiff base ligand in the basal plane and one O atom from an acetate group in the apical position. The acetate bridges linking the central and terminal M2+ ions are mutually trans. The M…M distances are 3.050(3) Å in 1, 3.139(2) Å in 2, and 3.287(6) Å in 3.