Titanium-Mediated Rearrangement of Bis(alkynyl)boranes: B─C Activation versus C─H Activation
Chenchang Ma1, Alexander Matler1, Shuai Zhu2
1Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, 97074, Würzburg, Germany.
Titanocene complexes react with bis(alkynyl)boranes to form novel titanium-boron ring structures. This work expands synthetic possibilities beyond amino-substituted boron compounds, revealing new metallocene architectures.
Area of Science:
- Organometallic Chemistry
- Main Group Chemistry
- Synthetic Inorganic Chemistry
Background:
- Titanocene complexes are versatile reagents in organometallic chemistry.
- Bis(alkynyl)boranes offer unique reactivity due to their unsaturated boron centers.
- Previous syntheses of titanium-boron heterocycles were limited by specific boron substituents.
Purpose of the Study:
- To investigate the reactions of titanocene synthons with diverse bis(alkynyl)boranes.
- To synthesize novel titanium-fused boracyclobutenes and tethered metallocene complexes.
- To explore new synthetic routes for organoboron compounds and understand reaction mechanisms.
Main Methods:
- Reaction of decamethyltitanocene (Cp*2Ti) synthon with various bis(alkynyl)boranes.
- Characterization of products using NMR spectroscopy and X-ray diffraction analysis.
- Computational studies to elucidate reaction mechanisms.
Main Results:
- Formation of titanium-fused boracyclobutenes from reactions with (Me3Si)2NB(CCR)2 and PhB(CCPh)2.
- Synthesis of novel tethered metallocene complexes via reactions with (Me3Si)PhNB(CCPh)2 and (Mes2B)PhNB(CCPh)2.
- Identification of an η2-coordinated bis(alkynyl)borane intermediate, leading to B-C or C-H activation pathways.
Conclusions:
- The study demonstrates a new method for synthesizing titanium-boron heterocycles, overcoming previous substituent limitations.
- Novel tethered metallocene complexes with unique bridging ligands were successfully prepared.
- An unprecedented reaction mechanism involving intermediate formation and subsequent activation pathways was elucidated.
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