Synthesis and magnetic properties of a series of 3d/4f/3d heterometallic trinuclear complexes incorporating in situ ligand formation
- 作者：Anthony S.R. Chesman1 ; anthony.chesman@csiro.au ; David R. Turner ; Boujemaa Moubaraki ; Keith S. Murray ; Glen B. Deacon ; Stuart R. Batten ; stuart.batten@sci.monash.edu.au ; stuart.batten@monash.edu
- 关键词：X-ray crystal structures ; Magnetism ; Lanthanoids ; Transition metal ; Metal cluster
- 刊名：Inorganica Chimica Acta
- 出版年：2012
- 期刊代码：40_00201693
- 类别：ch
- 出版时间：1 July, 2012
- 卷：389
- 期：Complete
- 页码：99-106
- 文件大小：1013 K
摘要
The dicyanonitrosomethanide (dcnm) ligand undergoes an in situ transition metal promoted nucleophilic addition of methanol to a nitrile group to form cyano(imino(methoxy)methyl)nitrosomethanide (cmnm) in the formation of the 3d/4f heterometallic complexes (Me4N)[{Ni(cmnm)3}2Ln(cmnm)2] (1Ln; 1Ln = 1La, 1Ce, 1Pr, 1Nd, 1Sm). A change in the counter-ions of the metal and ligand salts employed under alternate reaction conditions results in the formation of (Et4N)2[{Ni(cmnm)3}2Ln(dcnm)2](ClO4) (2Ln; 2Ln = 2La, 2Ce), in which unreacted dcnm ligands are coordinated to the central lanthanoid. In both types of complexes three cmnm ligands chelate to a nickel metal centre to form a [Ni(cmnm)3] metalloligand. Two of these metalloligands are then bound to a central lanthanoid via the nitroso oxygen atoms, resulting in a trinuclear complex in which each nickel cation is connected to the lanthanoid by three bridging nitroso groups. Variable temperature magnetic susceptibilities on these {Ni(S = 1), Ln(f0 to f5), Ni(S = 1)} spin systems reveal very weak to zero Ln-Ni or Ni-Ni exchange coupling with the thermal depopulation between Stark levels on the Ln centres being of similar magnitude, and the Ni2Ce and Ni2Pr cases giving strongest evidence for exchange coupling.