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Updated: Jun 21, 2026
10:51
The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
[CrBr2(NH3)4][CrBr4(NH3)2], a new chromium(III) complex
Ludwig Stork1, Xiaohui Liu, Boniface P T Fokwa
1Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, D-52056 Aachen, Germany.
Summary
Researchers synthesized green crystals of a novel chromium(III) complex, [CrBr2(NH3)4][CrBr4(NH3)2]. This study marks the first instance of mixed ammine-bromide chromium(III) ions in both cation and anion forms.
Area of Science:
- Inorganic Chemistry
- Crystallography
- Coordination Chemistry
Background:
- Chromium(III) complexes are widely studied for their diverse coordination environments and applications.
- Mixed ammine-bromide ligands offer unique structural and electronic properties in coordination compounds.
- Previous research has explored various chromium(III) complexes, but dual mixed-ligand ions in a single structure are less common.
Purpose of the Study:
- To synthesize and characterize the novel mixed ammine-bromide chromium(III) complex, [CrBr2(NH3)4][CrBr4(NH3)2].
- To elucidate the crystal structure and coordination geometry of the synthesized compound.
- To investigate the intermolecular interactions within the crystal lattice.
Main Methods:
- Single crystal X-ray diffraction was employed to determine the precise atomic arrangement.
- Spectroscopic techniques may have been used for preliminary characterization (though not explicitly stated in the abstract).
- Analysis of coordination numbers and symmetry elements within the crystal structure.
Main Results:
- Green single crystals of trans-tetraamminedibromidochromium(III) trans-diamminetetrabromidochromate(III), [CrBr2(NH3)4][CrBr4(NH3)2], were successfully obtained.
- The structure features two symmetry-independent sixfold coordinated Cr(III) cations located on inversion centers.
- The crystal lattice is a distorted CsCl-type structure, with octahedral [CrBr2(NH3)4]+ cations and [CrBr4(NH3)2]- anions linked by N-H...Br hydrogen bonds.
Conclusions:
- This work represents the first reported synthesis and structural characterization of a chromium(III) complex containing both mixed ammine-bromide cations and anions.
- The distorted CsCl-type structure highlights the specific packing arrangements influenced by the mixed-ligand ions.
- The N-H...Br interactions play a crucial role in stabilizing the overall crystal structure.
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