Related Experiment Video
Updated: Jul 10, 2026
06:34
Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)
Published on: June 20, 2014
[(Cyclen)(4)Ru(4)(pz)(4)](9+): a Creutz-Taube square
Victor C Lau1, Louise A Berben, Jeffrey R Long
1Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
Journal of the American Chemical Society
|August 1, 2002
Summary
Researchers assembled a mixed-valence square complex using cyclen (1,4,7,10-tetraazacyclododecane) and pyrazine ligands. This complex exhibits significant electron delocalization, exceeding that of the Creutz-Taube ion, as confirmed by electrochemical studies.
Area of Science:
- Coordination Chemistry
- Supramolecular Chemistry
- Electrochemistry
Background:
- Mixed-valence metal complexes are crucial for understanding electron transfer processes.
- The cyclen ligand (1,4,7,10-tetraazacyclododecane) is effective in stabilizing discrete multinuclear metal assemblies.
- Pyrazine-bridged ruthenium complexes have been extensively studied for their electronic properties.
Purpose of the Study:
- To synthesize and characterize a novel mixed-valence square complex of ruthenium.
- To investigate the electronic communication and electron delocalization within the complex.
- To compare the electron delocalization in this complex with existing benchmark systems like the Creutz-Taube ion.
Main Methods:
- Assembly of the mixed-valence square complex using cyclen and pyrazine ligands.
- Crystal structure determination to elucidate the molecular geometry and coordination environment.
- Cyclic voltammetry to probe the redox behavior and determine comproportionation constants.
Main Results:
- A regular square complex, [(cyclen)4Ru4(pz)4]9+, was successfully synthesized and structurally characterized.
- Electrochemical analysis revealed distinct redox waves corresponding to the mixed-valence states.
- The comproportionation constant (Kc = 108.9) indicated extensive electron delocalization, greater than in the Creutz-Taube ion.
Conclusions:
- The cyclen-based square complex demonstrates significant electronic communication between ruthenium centers.
- The observed electron delocalization is highly dependent on the oxidation state of the complex.
- This study provides insights into the design principles for multinuclear metal complexes with tunable electronic properties.
More Related Videos
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Related Concept Videos
02:27Predicting Molecular Geometry
VSEPR Theory for Determination of Electron Pair Geometries
02:57Coordination Number and Geometry
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.
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
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,...
02:11Conformations of Cyclohexane
Cyclohexane does not exist in a planar form due to the high angle and torsional strain it would experience in the planar structure. Instead, it adopts non-planar chair and boat conformations.
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
01:18Aromatic Hydrocarbon Anions: Structural Overview
Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
Due to the absence of continuous overlap of p...
Due to the absence of continuous overlap of p...
01:18Aromatic Hydrocarbon Cations: Structural Overview
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group with both...
Removing one hydrogen from the intervening CH2 group with both...