Related Experiment Video
Updated: Jul 5, 2025
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
14.0K
Synthesis and Reactivity of Fe(II) Complexes Containing Cis Ammonia Ligands
Alexander S Phearman1, R Morris Bullock1
1Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States.
Inorganic Chemistry
|January 17, 2024
Summary
Researchers explored iron complexes with specific ligands for ammonia oxidation, crucial for renewable energy. While electronic tuning affected ammonia binding, no catalytic ammonia oxidation to nitrogen was observed, limiting its renewable energy applications.
Area of Science:
- Inorganic Chemistry
- Electrochemistry
- Catalysis
Background:
- Developing earth-abundant transition-metal complexes is vital for electrocatalytic ammonia oxidation and a renewable energy economy.
- Understanding ammonia binding to metal complexes, influenced by ligand geometry and electronic effects, is key to advancing this field.
Purpose of the Study:
- To synthesize and characterize novel iron(II)-ammonia complexes.
- To investigate the impact of ligand electronic modifications on complex properties and ammonia oxidation.
Main Methods:
- Synthesis and characterization of Fe(II)-NH3 complexes with tetradentate ligands.
- Electrochemical studies including cyclic voltammetry and bulk electrolysis.
- Reactions with organic radicals (TEMPO, ArO•) to probe oxidation pathways.
Main Results:
- Electronic modifications of ligands altered Fe(III/II) redox potentials and NH bond acidities.
- No catalytic ammonia oxidation to N2 was observed across the tested conditions.
- 15N2 was detected exclusively in reactions involving ArO• radicals.
Conclusions:
- The studied iron complexes, despite electronic tuning, did not facilitate catalytic ammonia oxidation to nitrogen.
- Ligand design plays a critical role in modulating redox potentials and acidity, but not in achieving catalytic ammonia oxidation in this system.
Related Concept Videos
02:51Metal-Ligand Bonds
20.8K
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...
20.8K
01:07Ladder Diagrams: Complexation Equilibria
350
Ladder diagrams are useful for evaluating equilibria involving metal-ligand complexes. The vertical scale of the ladder diagram represents the concentration of unreacted or free ligand, pL. The horizontal lines on the scale depict the log of stepwise formation constants for metal-ligand complexes and indicate the dominant species in all the regions.
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...
350
01:09Complexation Equilibria: Factors Influencing Stability of Complexes
372
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...
372
01:19Complexation Equilibria: The Chelate Effect
518
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
518
02:34Structural Isomerism
19.2K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
19.2K
03:45Formation of Complex Ions
23.6K
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...
23.6K