Solvent Modulated Assembly of Two Ni(II) Complexes: Syntheses, Structures and Magnetic Properties

Abstract

A dinuclear [Ni2(L)2(DMSO)2(MeOH)2] (1) and a tetra‐nuclear [Ni4(L)4(DMF)2(H2O)2].DMF (2) Ni(II) complexes have been prepared by treating nickel nitrate hexahydrate with the Schiff base ligand H2L (H2L=(E)‐2‐(2‐hydroxybenzyliden)amino‐4‐nitrophenol) in a one‐pot reaction. Complex 1 was obtained after recrystallization of the precipitate from the reaction with a 1:1:1 mixture of DMSO/CH2Cl2/MeOH. In contrast, the tetrameric complex 2 was obtained after slow evaporation of the filtrate. Both complexes were characterized by analytical, thermogravimetric, optical and magnetic techniques. The solid state molecular structures of 1 and 2 were determined by single crystal X‐ray crystallography. Complex 1 shows a dinuclear structure whereas complex 2 shows a defective dicubane structure. The magnetic properties of complex 1 show a predominant ferromagnetic coupling between the Ni(II) ions with J=+16.1 cm−1 and 2 shows a predominant Ni−Ni antiferromangetic interaction of J=‐15.5 cm−1. Both coupling constants are the expected ones from magneto‐structural correlations. The thermal stability and optical properties of both complexes have also been investigated.

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

“…Both the Ni−O and Ni−N bond length are in consistent with the reported bond lengths of dinuclear Ni(II) complexes . The Ni1−O2−Ni2 and Ni1−O11−Ni2 angles in 1 are in the ranges 106.33(11) ° and 94.33(11) ° respectively.…”

“…Moreover, a singlet at 13.42 ppm confirms the presence of a hydrogen bonded proton attached to nitrogen atom and thus it suggesting stabilization of keto‐enamine form of the ligand. These values are in the range of reported values . A strong resonance signal in the 13 C{ 1 H} NMR spectrum of the ligand is observed at 55.8 ppm for the methoxy carbon atom –OMe (Figure S3).…”

“…Presence of [‐NO 2 ] groups can be confirmed due to the appearance of bands at 1479 and 1386 cm −1 . A strong band appears at 1646 cm −1 owing to [ν(C=O)] stretching of the DMF molecules . Moreover, a weak broad band around 3437 cm −1 indicates the presence of coordinated and free water molecules.…”

Trinuclear Lanthanide Coordination Clusters: Single‐Molecule‐Magnet Behavior and Catalytic Activity in the Friedel‐Crafts Alkylation Reaction

“…In complexes 1 and 2 , the [ν(C=N)] stretching vibrations are shifted to lower energies and appear at 1623 cm −1 and 1621 cm −1 , respectively. The existence of a band at around 1660 cm −1 which accounts for the [ν(C=O)] stretching, confirms the presence of DMF molecules in the structure of complexes 1 and 2 . This observation is further supported by single crystal X‐ray diffraction analyses ( vide infra ).…”

“…The existence of a band at around 1660 cm À 1 which accounts for the [ν(C=O)] stretching, confirms the presence of DMF molecules in the structure of complexes 1 and 2. [42,43] This observation is further supported by single crystal X-ray diffraction analyses (vide infra). As mentioned earlier, the ligand was not soluble in common organic solvents and, therefore, the 1 H spectrum was recorded in DMSO-d 6 .…”