Related Experiment Video
Updated: May 8, 2026
07:20
Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents
Published on: May 28, 2014
Tuning spin-spin coupling in quinonoid-bridged dicopper(II) complexes through rational bridge variation
David Schweinfurth1, Marat M Khusniyarov, Denis Bubrin
1Institut für Chemie und Biochemie, Freie Universität Berlin , Fabeckstrasse 34-36, D-14195, Berlin, Germany.
Inorganic Chemistry
|September 10, 2013
Summary
Synthesized copper(II) complexes with bridging quinonoid ligands exhibit tunable antiferromagnetic coupling. Ligand design influences electronic structure and magnetic interactions, demonstrating control over spin-spin coupling in metal complexes.
Area of Science:
- Coordination Chemistry
- Inorganic Chemistry
- Materials Science
Background:
- Bridged metal complexes offer tunable electronic and magnetic properties.
- Quinonoid ligands are versatile building blocks for constructing metal-organic frameworks.
- Understanding spin-spin coupling mechanisms is crucial for developing molecular magnets.
Purpose of the Study:
- Synthesize and characterize novel bridged copper(II) complexes with diverse quinonoid ligands.
- Investigate the structural and electronic properties of these complexes.
- Elucidate the relationship between ligand structure and magnetic coupling behavior.
Main Methods:
- Synthesis of bridged copper(II) complexes using copper(II) salts, tris(2-pyridylmethyl)amine (tmpa), and various quinonoid ligands.
- X-ray structural characterization to determine coordination environments and bonding.
- Temperature-dependent magnetic susceptibility measurements to probe magnetic interactions.
- Broken-symmetry density functional theory (DFT) calculations to analyze electronic structures and exchange pathways.
Main Results:
- Four bridged copper(II) complexes, [{Cu(tmpa)}2(μ-L(1)-2H)](ClO4)2 (1), [{Cu(tmpa)}2(μ-L(2)-2H)](ClO4)2 (2), [{Cu(tmpa)}2(μ-L(3)-2H)](BPh4)2 (3), and [{Cu(tmpa)}2(μ-L(4)-2H)](ClO4)2 (4), were successfully synthesized.
- Complexes 1-3 exhibited distorted octahedral copper(II) centers, while complex 4 showed a distorted square-pyramidal geometry.
- Antiferromagnetic coupling was observed in all complexes, with coupling strength dependent on the bridging ligand's Highest Occupied Molecular Orbital (HOMO) energy.
- DFT calculations revealed distinct magnetic orbital orientations and two different exchange pathways in the complexes.
Conclusions:
- Rational design of bridging quinonoid ligands allows for fine-tuning of spin-spin coupling in copper(II) complexes.
- The [O] for [NR] isoelectronic analogy provides a strategy for controlling electronic properties and magnetic exchange.
- These findings contribute to the development of novel materials with tailored magnetic properties.
Related Concept Videos
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
01:17Spin–Spin Coupling: One-Bond Coupling
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
01:08Spin–Spin Coupling Constant: Overview
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
02:42Valence Bond Theory
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...
03:02Colors and Magnetism
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 eye.
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 eye.