Controlled Ligand Deprotonation in Lanthanide Chelates with Asymmetric Semicarbazone/Benzoylhydrazone or Semicarbazone/Thiosemicarbazone Coordination Spheres
详细信息 查看全文
- 作者：Alexander Jagst ; Agustin Sanchez ; Ezequiel M. Vazquez-Lopez ; and Ulrich Abram
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：August 8, 2005
- 年：2005
- 卷：44
- 期：16
- 页码：5738 - 5744
- 全文大小：434K
- 年卷期：v.44,no.16(August 8, 2005)
- ISSN：1520-510X
文摘
Asymmetric, potentially pentadentate ligands (H2L3) are formed by subsequent condensation of a semicarbazideand benzoylhydrazine on 2,6-diacetylpyridine. Two equivalents of H2L3 reacts with CeCl3·7H2O, Ce(SO4)2·4H2O, orEuCl3·6H2O under formation of [LnIII(HL3)2]+ cations (Ln = Ce, Eu) with exclusive deprotonation of thebenzoylhydrazone ligand arms. The Ce4+ ion of the sulfate salt is reduced during the reaction and forms 10-coordinate singly charged complex cations, the structure of which is identical to the product of the reaction ofcerium(III) chloride. The exact position of deprotonation in the ligands is resolved by infrared spectroscopy, bondlengths considerations, and the hydrogen bonding in the solid-state structures of the products. A similar approachallows the synthesis of mixed semicarbazone/thiosemicarbazone ligands (H2L4). The reaction of H2L4 with Sm(NO3)3·6H2O leads to the first structurally characterized lanthanide complex with thiosemicarbazone coordination.The solid-state structure of the 10-coordinate complex [Sm(HL4)2]NO3·H2O shows exclusive deprotonation of thethiosemicarbazone arms of the ligands. All isolated complexes are air stable and do not undergo ligand exchangereactions or hydrolysis in the presence of water.