Some new metal(II) dichloride complexes with the ligands substituted nitrones of the
general formula [ML2Cl2], where M= Co(II), Ni(II), Cu(II), Zn(II) and Cd(II),
L=OCH=CHCH=C-CH=N(O)C6H4X (X=H,p-CH3,CH3O,CH3CO,F,Cl,and Br) have
been prepared and characterized by elemental analysis, IR,1H,13C NMR and Vis/Uv
spectroscopy. The IR spectral data showed that the nitrone ligands coordinated with
the metal ion through the most active atom of the N-oxide to give square planner
coordinate (Cu,Ni,) complexes and (Zn,Cd,Co) tetrahedral complexes. No correlation
was observed between the N-O vibrations stretching hing frequency ν(N-O) of the
complexes and the Hammet (σ) constants.
Table of Contents
Abstract
Introduction
EXPERIMENTAL
Results and Discussion
Molar conductivities
NMR Spectra
Research Objectives and Focus
This study aims to synthesize and characterize new metal(II) dichloride complexes using substituted N-aryl furfural nitrones as ligands. The research focuses on investigating the coordination behavior of these ligands with Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) ions, determining the structures of the resulting complexes, and analyzing the electronic and magnetic properties of these compounds.
- Synthesis of new metal(II) dichloride complexes with N-aryl furfural nitrone ligands.
- Spectroscopic characterization using IR, 1H NMR, 13C NMR, and Vis/Uv spectroscopy.
- Determination of the coordination geometry (square-planar vs. tetrahedral) for the different metal ions.
- Evaluation of the influence of substituents on the complex formation using the Hammett equation.
Excerpt from the Book
Results and Discussion
The IR data in Table I confirmed the formation of the complexes. There are changes in the frequencies of the C=N band upon complexation, but especially significant is the appearance of a new band at ca. 340 cm-1, attributed to υ(M-O), which served as a good indicator of coordination.( 15). Moreover, the drastic shift in the υ(N-O) frequency is clear evidence for the interaction between the NO group of the nitrone ligand and metal. However, coordinatid lead to a shift to lower frequency and the values of ν(NO)complex- ν (NO)ligand showed a systematic variations from 15-to-50 cm-1 (Table1), and this may be attributed to a decrease in the NO group upon coordination(16). On the other hand the ν (C=N) frequency of the ligand show a great change to a higher values upon coordination and the values of ν (CN)complex- ν (CN)ligand show again systematic variations from 25 to 45cm-1. This may be due to the increase in the bond order between C and N upon coordination. In contrast, the ν (C-O) frequency of the ligand which appeared in the range (17) 1070-1090cm-1 remains almost constant upon coordination supported that the furfural oxygen remained unchenged upon coordination supported that the furfural oxygen is not involved in the coordination.
Chapter Summaries
Abstract: Provides a concise overview of the synthesis and characterization of new metal(II) complexes, highlighting the analytical methods used and the observed coordination geometries.
Introduction: Reviews the biological importance of nitrone compounds and their derivatives, justifying the need for new methods of activation through microwave chemistry and metal coordination.
EXPERIMENTAL: Details the materials and standard methods used for the preparation, purification, and physical analysis of the nitrone ligands and their subsequent metal complexes.
Results and Discussion: Analyzes the infrared, NMR, and electronic spectral data to determine the bonding, coordination sites, and geometric structures of the synthesized complexes.
Molar conductivities: Reports conductivity measurements in different solvents to confirm the non-ionic nature of the prepared complexes.
NMR Spectra: Examines shifts in chemical signals to confirm coordination and determine the electronic effects of substituents on the metal-ligand interaction.
Keywords
Metal complexes, N-aryl furfural nitrones, Co(II), Ni(II), Cu(II), Zn(II), Cd(II), IR spectroscopy, NMR spectroscopy, Coordination geometry, Hammett equation, Ligands, Square-planar, Tetrahedral.
Frequently Asked Questions
What is the primary objective of this research?
The study aims to synthesize and characterize new metal(II) dichloride complexes using substituted N-aryl furfural nitrone ligands and to elucidate their structural and electronic properties.
Which metal ions were investigated in this study?
The study focuses on complexes of Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) chlorides.
What is the main research question or goal regarding the ligands?
The goal is to determine how the nitrone ligands coordinate to the metal center and to assess the influence of different substituents on the formation and properties of these complexes.
Which scientific methods were employed to characterize the complexes?
The characterization included elemental analysis, infrared (IR) spectroscopy, 1H and 13C NMR spectroscopy, Vis/Uv spectroscopy, and molar conductivity measurements.
What is covered in the results and discussion section?
This section discusses the spectroscopic evidence for the formation of metal-oxygen bonds, the determination of coordination geometries (square-planar vs. tetrahedral), and the magnetic and spectral behaviors of the complexes.
Which key terms characterize this study?
The study is characterized by terms such as nitrone ligands, metal coordination, spectroscopic analysis, Hammett constants, and geometric structure determination.
How does the Hammett equation relate to the study's findings?
The authors used the Hammett equation to investigate the effect of substituents on the mechanism of complex formation, though they observed no clear correlation between N-O vibration frequencies and Hammett (σ) constants.
What do the molar conductivity measurements imply?
The low molar conductivity values in solvents like ethanol and DMF suggest that the synthesized complexes are non-conductive, indicating that they are non-ionic species.
- Citation du texte
- Amer Taqa (Auteur), 2011, Some Complexes of N-Aryl Furfural Nitrones with Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) Chlorides, Munich, GRIN Verlag, https://www.grin.com/document/209690
