Chromous siloxides of variable nuclearity and magnetism
Simon P O Trzmiel1, Jan Langmann2, Cäcilia Maichle-Mössmer1
1Institute of Inorganic Chemistry, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, D-72076 Tübingen, Germany. reiner.anwander@uni-tuebingen.de.
Dalton Transactions (Cambridge, England : 2003)
|March 9, 2022
Summary
This study synthesizes novel chromium(II) siloxide complexes, detailing their structural transformations and magnetic properties. The research highlights the influence of ligands on chromium coordination and magnetic behavior in these organometallic compounds.
Area of Science:
- Organometallic Chemistry
- Inorganic Synthesis
- Coordination Chemistry
Background:
- Chromium complexes with siloxide ligands are of interest due to their unique structural and magnetic properties.
- Understanding the reactivity of low-valent chromium precursors is crucial for developing new synthetic methodologies.
Purpose of the Study:
- To synthesize and characterize novel chromium(II) siloxide complexes.
- To investigate the structural diversity and magnetic properties of these complexes.
- To explore the influence of different ligands (THF, TMEDA) on chromium coordination and reactivity.
Main Methods:
- Synthesis of chromium(II) siloxide complexes via reaction of Cr[N(SiMe3)2]2(thf)2 with HOSiR3.
- Structural characterization through solvent removal and ligand exchange.
- Magnetic measurements (Evans and SQUID) to determine magnetic moments and interactions.
Main Results:
- Formation of bridged Cr(II) siloxide complexes (e.g., Cr3(OSiEt3)2(μ-OSiEt3)4(thf)2) and homoleptic derivatives (e.g., Cr4(μ-OSiEt3)8).
- Synthesis of a monomeric cis-coordinated siloxide, Cr(OSiiPr3)2(tmeda), using N,N,N',N'-tetramethylethane-1,2-diamine (TMEDA).
- Oxidation reactions yielding Cr(III) and asymmetrically coordinated Cr(II) complexes.
- Magnetic studies revealing antiferromagnetic interactions in Cr(II) centers and higher effective magnetic moments in cis-coordinated complexes.
Conclusions:
- The study successfully synthesized a range of chromium siloxide complexes with diverse structures.
- Ligand choice significantly impacts the coordination geometry and magnetic properties of chromium centers.
- The tetranuclear complex Cr4(μ-OSiEt3)8 exhibits notable magnetic behavior.
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