Related Experiment Video
Updated: Jun 19, 2026

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Composition and structure of polynuclear chromium(III) hydroxo complexes
Natallia Torapava1, Artsiom Radkevich, Dmitri Davydov
1Department of Chemistry, Swedish University of Agricultural Sciences, P. O. Box 7015, SE-750 07 Uppsala, Sweden.
Chromium(III) hydrolysis forms tetrameric complexes in acidic solutions and polymeric chains in alkaline solutions. These structures were elucidated using X-ray absorption and scattering techniques, revealing complex chromium speciation.
Area of Science:
- Inorganic Chemistry
- Materials Science
- Solution Chemistry
Background:
- Chromium(III) speciation in aqueous solutions is crucial for understanding its environmental behavior and industrial applications.
- Previous studies suggested mononuclear tetrahydroxochromate(III) complexes in alkaline media.
Purpose of the Study:
- To determine the structures of polynuclear chromium(III) hydrolysis complexes in acidic and alkaline aqueous solutions.
- To investigate the pH-dependent speciation and structural transformations of chromium(III).
Main Methods:
- Extended X-ray absorption fine structure (EXAFS) spectroscopy.
- Large angle X-ray scattering (LAXS).
Main Results:
- Below pH 3-4, chromium(III) exists as mononuclear hydrated ions.
- In concentrated aged solutions above pH 4, cationic tetrameric complexes with hydroxo bridges form.
- In highly alkaline solutions (pH 15), polymeric chains of six-coordinated chromium(III) ions linked by double hydroxo bridges were observed, contrary to literature.
- These polymers precipitate into an amorphous phase resembling alpha-chromium(III) oxide hydroxide at pH < 15.
Conclusions:
- The study reveals novel polynuclear structures of chromium(III) hydrolysis complexes, particularly polymeric chains in alkaline solutions.
- Accurate structural determination of chromium(III) species is essential for predicting its fate and transport in various environments.
More Related Videos
10:52Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
10:42Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of Chalcogenidoplumbates(II or IV)
Published on: December 29, 2016
Related Concept Videos
Complexation Equilibria: The Chelate Effect
Valence Bond Theory
Coordination Compounds and Nomenclature
Coordination Number and Geometry
Formation of Complex Ions
Crystal Field Theory - Octahedral Complexes
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...