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Spontaneous dehydrocoupling in peri-substituted phosphine-borane adducts.
Laurence J Taylor1, Brian A Surgenor, Piotr Wawrzyniak
1School of Chemistry, EastCHEM, University of St Andrews, St Andrews, Fife, KY16 9ST, UK. pk7@st-andrews.ac.uk.
New bis(borane) adducts were synthesized and found to undergo spontaneous dehydrocoupling at room temperature, yielding novel bridged species. These reactions offer a catalyst-free pathway for generating unique chemical structures.
Area of Science:
- Organometallic Chemistry
- Boron Chemistry
- Coordination Chemistry
Background:
- Phosphine-borane adducts are versatile reagents in synthesis.
- Dehydrocoupling reactions offer pathways to new materials.
- Acenaphthene-based ligands provide unique structural scaffolds.
Purpose of the Study:
- To synthesize novel bis(borane) adducts based on acenaphthene.
- To investigate the dehydrocoupling behavior of these adducts.
- To characterize the resulting bridged species.
Main Methods:
- Synthesis of bis(borane) adducts via reaction with excess borane-dimethyl sulfide.
- Room temperature dehydrocoupling of bis(borane) adducts.
- Thermolysis of resulting bridged species.
- Single crystal X-ray diffraction for structural analysis.
Main Results:
- Successful synthesis of bis(borane) adducts Acenap(PiPr2·BH3)(PRH·BH3) (4a-c).
- Spontaneous, catalyst-free dihydrogen elimination at room temperature yielding BH2-bridged species (5a-c).
- Thermolysis of 5c leads to loss of a borane moiety, forming Acenap(PiPr2)(μ-BH2)(PH) (14).
- X-ray structures of key intermediates and products were determined.
Conclusions:
- Bis(borane) adducts of acenaphthene undergo facile dehydrocoupling.
- Catalyst-free formation of BH2-bridged species is achievable.
- The reported compounds offer new structural motifs in organoboron chemistry.
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