Syntheses, X-Ray Crystal Structures, and Magnetic Properties of Novel Linear MUIV Complexes (M=Co, Ni, Cu, Zn)

Authors:
Publisher website
Google Scholar
Abstract
Attempts to prepare heterobimetallic complexes in which 3d and uranium magnetic ions are associated by means of the Schiff bases H2Li derived from 2‐hydroxybenzaldehyde or 2‐hydroxy‐3‐methoxybenzaldehyde were unsuccessful because of ligand transfer reactions between [MLi] (M=Co, Ni, Cu) and UCl4 that led to the mononuclear Schiff base complexes of uranium [ULiCl2]. The crystal structure of [UL3Cl2(py)2] [L3=N,N′‐bis(3‐methoxysalicylidene)‐ethylenediamine; py=pyridine] was determined. The hexadentate Schiff base ligand N,N′‐bis(3‐hydroxysalicylidene)‐2,2‐dimethyl‐1,3‐propanediamine (L) was useful for the synthesis of novel trinuclear complexes of the general formula [{ML(py)}2U] (M=Co, Ni, Zn) or [{CuL(py)}M′{CuL}] (M′=U, Th, Zr) by reaction of [M(H2L)] with [M′(acac)4] (acac=MeCOCHCOMe). The crystal structures of the Co2U, Ni2U, Zn2U, Cu2U, and Cu2Th complexes show that the two ML fragments are orthogonal, being linked to the central actinide ion by the two pairs of oxygen atoms of the Schiff base ligand. In each compound, the UO8 core exhibits the same dodecahedral geometry, and the three metals are linear. The magnetic study indicated that the two Cu2+ ions are not coupled in the Cu2Zr and Cu2Th compounds. The magnetic behavior of the Co2U, Ni2U, and Cu2U complexes was compared with that of the Zn2U derivative, in which the paramagnetic 3d ion was replaced with the diamagnetic Zn2+ ion. A weak antiferromagnetic coupling was observed between the Ni2+ and the U4+ ions, while a ferromagnetic interaction was revealed between the Cu2+ and U4+ ions.

This publication has 61 references indexed in Scilit: