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Two alternative approaches to access mixed hydride-amido zinc complexes: synthetic, structural and solution
Andrew J Roberts1, William Clegg, Alan R Kennedy
1WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, UK. eva.hevia@strath.ac.uk stuart.d.robertson@strath.ac.uk.
Dalton Transactions (Cambridge, England : 2003)
|April 8, 2015
Summary
This study synthesizes novel N-heterocyclic carbene stabilized zinc complexes using bis(amide) zinc and two hydride sources. Different hydride sources yield distinct zinc hydride complexes, showcasing unique stabilization and solution behaviors.
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Synthetic Chemistry
Background:
- Bis(amide) zinc complexes serve as versatile precursors in organometallic synthesis.
- N-heterocyclic carbenes (NHCs) are crucial ligands for stabilizing reactive metal species.
- Understanding the reactivity of zinc hydride complexes is key to developing new catalytic systems.
Purpose of the Study:
- To explore the synthesis of NHC-stabilized mixed amido-hydride zinc complexes.
- To investigate the influence of different hydride sources (dimethylamine borane and phenylsilane) on the resulting zinc complexes.
- To characterize the structure and solution behavior of these novel zinc complexes.
Main Methods:
- Synthesis of zinc complexes using bis(amide) zinc precursor, dimethylamine borane (DMAB), phenylsilane (PhSiH3), and N-heterocyclic carbenes (IPr, IXy).
- Characterization using Nuclear Magnetic Resonance (NMR) spectroscopy, including Diffusion Ordered Spectroscopy (DOSY) experiments.
- Isolation and structural elucidation of key intermediates and products.
Main Results:
- Reaction with DMAB yielded a hydride-rich zinc cluster, Zn4(HMDS)2H6·2IPr, stabilized by the bulky IPr carbene.
- Reaction with phenylsilane afforded a monomeric heteroleptic hydride, (HMDS)ZnH·IPr.
- NMR studies revealed distinct solution behaviors for the complexes, with one exhibiting complex equilibria in lower polarity solvents.
Conclusions:
- The choice of hydride source significantly impacts the structure and stability of NHC-stabilized zinc complexes.
- Bulky NHCs play a critical role in stabilizing hydride-rich zinc clusters.
- The characterized zinc complexes offer insights into the coordination chemistry and reactivity of zinc hydrides.
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