Macrocyclic lanthanide(III) complexes of iminophenol Schiff bases and carboxylate anions: Syntheses, structures and luminescence properties

The mixed-ligand lanthanide(III) complexes derived from the tetraiminodiphenolate ((LH2)-H-1) or octaimino-tetraphenolate ((LH4)-H-2) macrocyclic ligands and acetate (OAc-) or benzoate (OBz(-)) anions have been synthesized and structurally characterized. With the ligand combination (LH2)-H-1 and OBz(-), either the dimeric complexes [{Ln((LH2)-H-1)}(2)(mu(2)-eta(1):eta(1)-OBz)(4)](ClO4)(2) (Ln = La (1), Nd (2) and Eu (3)) or the monomeric complexes [Ln((LH2)-H-1)(eta(2)-OBz)(2)](ClO4)center dot n solvent (Ln = Tb (4), Lu (5) and Y (6)) have been obtained. The X-ray crystal structures of 1, 4 and 6 have been determined, of which 4 and 6 have the same structure. (LH2)-H-1 and OAc- combination affords the dimeric complexes [{Ln((LH2)-H-1)(eta(2)-OAc)(mu-OAc)}(2)](ClO4)(2) (Ln = La (7), Nd (8) and Y (9)) and the structure of 9 has been determined. In complexes 1-9, (LH2)-H-1 uses two imino nitrogens and the two phenolate oxygens for metal coordination, while the other two uncoordinated imine nitrogens are protonated and intramolecularly hydrogen-bonded to the phenolate oxygens. The metal centre in all the cases is 8-coordinate and has distorted square antiprism geometry. With the octaiminotetraphenolate macrocyclic ligand ((LH4)-H-2) dinuclear complexes of composition [Ln(2)((LH4)-H-2)(OAc)(2) (NO3)(4)]center dot nH(2)O (Ln = La (10), Pr (11), Nd (12) and Y (13)) have obtained. The structures determined for 11 and 12 have shown that they are isostructural and there are two independent molecules (A and B) in the unit cell. The molecule A has the bond types [Ln(2)((LH4)-H-2)(eta(2)-OAc)(2)(eta(2)-NO3)(2)(eta(1)-NO3)(2)] and its 9-coordinate metal centre obtains a tricapped trigonal prismatic geometry, while the molecule B is [Ln(2)((LH4)-H-2)(eta(2)-OAc)(2)(eta(2)-NO3)(4)] whose 10-coordinate metal centre has a sphenocorona geometry. In these compounds, four uncoordinated imine nitrogens are protonated and hydrogen-bonded to the phenolate oxygens. The luminescence spectra of [{Eu((LH2)-H-1)}(2)(mu-OBz)(4)](2+) (3(2+)) in acetonitrile (at 298 K) and in acetonitrile-toluene glassy matrix (at 77 K) have been studied. (C) 2012 Elsevier Ltd. All rights reserved.