Related Experiment Video
Updated: Dec 24, 2025
11:14
Anticancer Metal Complexes: Synthesis and Cytotoxicity Evaluation by the MTT Assay
Published on: November 10, 2013
58.6K
Electronic Structure and Magnetic Properties of a Titanium(II) Coordination Complex
Eva M Zolnhofer1, Gayan B Wijeratne2, Timothy A Jackson2
1Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany.
Inorganic Chemistry
|April 14, 2020
Summary
Stable low oxidation state titanium complexes are rare. This study revisits trans-[TiCl2(tmeda)2], providing a modified synthesis, crystal structure, and detailed electronic characterization of this high-spin TiII complex.
Area of Science:
- Coordination Chemistry
- Organometallic Chemistry
- Computational Chemistry
Background:
- Stable coordination complexes of TiII (3d2) are uncommon and valuable as synthons for low oxidation state titanium chemistry.
- High-spin TiII ions supported by redox-inactive ligands are particularly rare due to the strong reducing nature of TiII.
- The complex trans-[TiCl2(tmeda)2] was previously reported but lacked detailed spectroscopic and theoretical characterization.
Purpose of the Study:
- To synthesize and characterize the rare high-spin TiII complex trans-[TiCl2(tmeda)2].
- To elucidate the electronic structure of this complex using a combination of experimental and computational methods.
- To provide insights into the behavior of low oxidation state early transition metal complexes.
Main Methods:
- Modified synthesis of trans-[TiCl2(tmeda)2].
- Low-temperature (100 K) X-ray crystallography.
- Magnetometry, high-frequency and -field electron paramagnetic resonance (HFEPR), and variable-temperature, variable-field magnetic circular dichroism (VTVH-MCD) spectroscopies.
- Quantum chemical theory (QCT) calculations, including density functional theory (DFT) and ab initio methods.
Main Results:
- A modified synthesis and a low-temperature crystal structure of trans-[TiCl2(tmeda)2] were obtained.
- Spin Hamiltonian parameters (D = -5.23(1) cm-1, E = -0.88(1) cm-1, g = [1.86(1), 1.94(2), 1.77(1)]) were determined experimentally.
- Combined spectroscopic and QCT studies provided a comprehensive understanding of the complex's electronic structure.
Conclusions:
- The study successfully characterized the rare high-spin TiII complex trans-[TiCl2(tmeda)2].
- The detailed electronic structure was elucidated through advanced spectroscopic and computational techniques.
- This work contributes to the understanding of low oxidation state early transition metal chemistry and provides a benchmark for future studies.
Related Concept Videos
02:42Valence Bond Theory
10.8K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
10.8K
03:02Colors and Magnetism
13.6K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
13.6K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
47.5K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
47.5K
02:58Crystal Field Theory - Octahedral Complexes
30.1K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
30.1K
02:57Coordination Number and Geometry
18.5K
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.
18.5K
02:54Coordination Compounds and Nomenclature
25.8K
In most main group element compounds, the valence electrons of the isolated atoms combine to form chemical bonds that satisfy the octet rule. For instance, the four valence electrons of carbon overlap with electrons from four hydrogen atoms to form CH4. The one valence electron leaves sodium and adds to the seven valence electrons of chlorine to form the ionic formula unit NaCl (Figure 1a). Transition metals do not normally bond in this fashion. They primarily form coordinate covalent bonds, a...
25.8K