Related Experiment Video
Updated: Aug 7, 2026
06:31
Preparation of SNS Cobalt(II) Pincer Model Complexes of Liver Alcohol Dehydrogenase
Published on: March 19, 2020
Biliverdine-based metalloradicals: sterically enhanced noninnocence
1Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway.
Inorganic Chemistry
|June 20, 2006
Summary
Transition-metal biliverdine complexes are noninnocent, featuring ligand radicals. Steric effects influence their electronic structures, unlike metallocorroles.
Area of Science:
- Inorganic Chemistry
- Computational Chemistry
- Materials Science
Background:
- Transition-metal complexes with biliverdine ligands are relatively unexplored.
- Understanding ligand noninnocence is crucial for predicting complex behavior.
Purpose of the Study:
- To perform a first density functional theory (DFT) survey of transition-metal biliverdine complexes.
- To investigate the electronic structures and bonding characteristics of Mn, Fe, Co, and Cu biliverdines.
Main Methods:
- Density Functional Theory (DFT) calculations were employed.
- Electronic structures and metal-ligand bonding were analyzed for key transition metals.
Main Results:
- All investigated transition-metal biliverdines exhibit noninnocent electronic structures, featuring a Blv*2- ligand radical.
- Copper biliverdines exist as Cu(II)Blv*2- species, unlike diamagnetic Cu(III) corroles.
- Iron biliverdines feature high-spin Fe(III) with elongated Fe-N bonds, differing from high-valent iron corroles.
Conclusions:
- Biliverdine complexes show a strong propensity for noninnocent electronic structures.
- Steric factors, specifically O...O nonbonded contacts in biliverdines, prevent short metal-N bonds, influencing metal oxidation states.
- Steric effects play a significant role in modulating electronic structures and noninnocence in transition-metal complexes.
Related Concept Videos
02:51Metal-Ligand Bonds
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
01:10Radical Reactivity: Steric Effects
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic factors, steric factors also account...
Along with electronic factors, steric factors also account...
02:32Bonding in Metals
Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Drüde called the “Electron Sea Model”.
01:23Properties of Organometallic Compounds
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
01:24ortho–para-Directing Deactivators: Halogens
Halogens are ortho–para directors. They are more electronegative than carbon. Therefore, as ring substituents, they can withdraw electrons through the inductive effect and deactivate the aromatic ring towards electrophilic substitution. Halogens also have an electron-donating resonance effect on the ring, which influences the orientation of the incoming electrophile. If an electrophile attacks at the ortho or the para position, the halogen donates electrons and stabilizes the intermediate...
01:16Radical Reactivity: Nucleophilic Radicals
Radicals adjacent to electron-donating groups are called nucleophilic radicals. These radicals readily react with electrophilic alkenes. The SOMO–LUMO interactions are the driving force for the reaction, where the high-energy SOMO of the electron-rich, nucleophilic radicals interacts with the low-energy LUMO of the electron-deficient, electrophilic alkenes. Such SOMO–LUMO interactions are the basis of reactive radical traps, affecting the selectivity in radical reactions. For instance, consider...