Mono-, homo- and hetero-dinuclear lanthanide(III) complexes with new acyclic compartmental schiff bases

Abstract

A series of homo-dinuclear lanthanide(III) complexes of the type: Ln 2(L A)(X) 2·. n(H 2O) and Ln 2(L B)(X) 2·. n(H 2O) (H 4L A and H 4L B are the Schiff bases obtained by condensation of 3-formylsalicylic acid and 4- N-dodecyldiethylenetriamine or 1,5-diamino-3-azapentane, respectively; X=NO 3 −, Cl −; n= 3−8;) has been prepared and characterized. The synthesis of mono- and hetero-dinuclear complexes failed. On the contrary, mono-, homo- and hetero-dinuclear lanthanide(III) complexes, Ln(H 4L C(NO 3) 3· nS, Ln(H 4L D)(NO 3) 3· nS or La(H 4L E)(NO 3) 3·4H 2O, Ln 2(L C)(NO 3) 2· nS, Ln 2(L D)(NO 3) 2· nS or La 2(L E)(NO 3) 2·4H 2O, Ln 1Ln 2(L C)(NO 3) 2· nS or Ln 1Ln 2(L D)(NO 3) 2· nS (n=1−3; SH 2O, CH 3OH), respectively, have been prepared by using the ligands H 4L C, H 4L D and H 4L E, which are the Schiff bases derived by condensation of 2,3-dihydroxybenzaldehyde with 1,5-diamino-3-azapentane, 1,5-diamino-3-thiapentane or 4- N-dodecyldiethylenetriamine, respectively. The metal/metal ratio and the homogeneity of the hetero-dinuclear complexes have been evaluated also by electron microscopy together with X-ray fluorescence microprobe. The physicochemical properties of the prepared complexes have been compared with those of similar macrocyclic complexes. The magnetic behaviour of the complex Gd 2(L A)(NO 3) 2·4H 2O has revealed a decrease in the effective magnetic moment from 10.97 μ B at room temperature to 7.96 μ B at 4.2 K, and an antiferromagnetic coupling constant J=0.211(4) cm −1. A superexchange mechanism through the bridging atoms has been proposed.