The Missing Link in Ni(II)‐Ln(III) System: Design and Synthesis of a Dinuclear [Ni₂] and Three Pentanuclear [Ni₃Ln₂] (Ln=La, Ce, Eu) Complexes of a Schiff Base Ligand

Abstract

A new Schiff base ligand N‐(2‐hydroxyphenyl‐3‐methoxy‐salicylideneamine)‐5‐nitrophenol (H2L) has been synthesized by the reaction of o‐vanillin with 2‐amino‐4‐nitrophenol. The ligand H2L has been employed to prepare homo‐ and heteronuclear metal complexes. For example, a dinuclear Ni(II) complex, [Ni2(L)2(H2O)3]⋅2DMF⋅3H2O (1) and a new family of three pentanuclear heterometallic [Ni3Ln2L6(H2O)4(DMF)2]⋅4DMF (Ln=La (2), Ce (3) and Eu (4) were prepared by the reaction of it with nickel nitrate hexahydrate and hydrated lanthanide nitrates. The solid state structures of ligand (H2L) and complexes 1–4 were determined by single crystal X‐ray diffraction analyses. Single crystal X‐ray diffraction and NMR data reveal that the ligand H2L exist as a keto‐enamine form in the solid state. Structure of complex 1 indicates formation of a dinuclear Ni(II) complex. Complexes 2–4 are isostructural and exhibits a butterfly‐like structure containing two Ln(III) ions and three Ni(II) ions. The Ni(II) and Ln(III) are bridged by phenoxo and aqua ligands resulting a pentanuclear chain with alternating Ni(II) and Ln(III) ions. Different coordination modes of ligand (H2L) have been explored. To the best of our knowledge, such pentanuclear complexes containing Ni−Ln and Schiff base ligand are hitherto unknown. The thermal stability and optical properties of all complexes are also investigated.

Lanthanide (III) Metal‐Organic Frameworks: Syntheses, Structures and Supercapacitor Application

“…The Ce2 is positioned at the centre of a polyhedron formed by seven oxygen atoms (O5, O7‐O11, and O15) from four [TATMB] 3− ligands, two oxygen atoms (O13 and O14) from two DMSO molecules and one water molecule (figure b). The Ce–O bond lengths lie in the range of 2.478(8)‐2.822(7) Å, which are in close agreement with other cerium(III) containing compounds …”

Syntheses, Structures, and Magnetic Properties of a Series of Heterotri-, Tetra- and Pentanuclear LnIII–CoII Compounds

“…The pentanuclear compounds reported in the literature are mostly concentrated in the 3d metal region [ 23 , 24 , 25 , 26 ], and the pentanuclear compounds of 3 d– 4 f heterometallic metals are relatively few [ 27 , 28 , 29 ]. In the reported 3 d– 4 f pentanuclear compounds, the arrangement shapes of pentanuclear metals can be roughly divided into the following types: (a) Trigonal-bipyramidal type [ 30 ], (b) Goblet-like [ 31 ], (c) Butterfly-shaped [ 32 ], (d) Open-book type [ 33 ], (e) T-shaped [ 34 ] and (f) Sandwich-type [ 35 ]. Only one case is similar to the linear structure reported in this paper [ 36 ].…”

Self-assembly of Schiff base anions and the trapping of HO−, O2− and Piv− bridges in a family of Ni3Ln4 complexes: synthesis, structures and magnetic properties

“…14 So far, many such heterometallic complexes that incorporate Ni II and 4f ions of varying nuclearity are known. These include dinuclear NiLn, 15 trinuclear Ni 2 Ln 16 or Ln 2 Ni, 17 tetranuclear Ni 2 Ln 2 18 or Ni 3 Ln, 19 pentanuclear Ni 3 Ln 2 , 20 hexanuclear Ni 4 Ln 2 , 21 Ni 3 Ln 3 14 b or Ni 2 Ln 4 , 22 heptanuclear Ni 4 Ln 3 , 23 Ni 3 Ln 4 24 or Ni 6 Ln, 25 octanuclear Ni 4 Ln 4 26 or Ni 5 Ln 3 , 27 nonanuclear Ni 6 Ln 3 , 28 and higher nuclear complexes. 29 However, reports on heptanuclear Ni–Ln complexes are rare, and the Ni 3 Ln 4 topology reported in this work is unprecedented in the literature.…”