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Ligand exchanges and selective catalytic hydrogenation in molecular single crystals
Zheng Huang1, Peter S White, Maurice Brookhart
1Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
Nature
|June 4, 2010
Summary
Single crystals undergo rare transformations, but this study shows intact iridium complex crystals exchanging ligands. This enables selective catalysis within the solid state, like hydrogenation.
Area of Science:
- Solid-state chemistry
- Organometallic chemistry
- Catalysis
Background:
- Single crystal to single crystal (SC-SC) transformations are uncommon due to difficulty retaining crystallinity after atomic rearrangement.
- Existing SC-SC transformations are mainly in porous materials or photo-induced reactions in organic crystals.
- SC-SC transformations in nonporous molecular inorganic or organometallic crystals involving metal-ligand bond changes are rare.
Purpose of the Study:
- To report a series of SC-SC transformations in molecular single crystals of a pincer iridium(I) complex.
- To demonstrate ligand interchange reactions at an iridium center within intact single crystals.
- To reveal selective catalysis within a nonporous molecular crystal.
Main Methods:
- Investigated SC-SC transformations involving the exchange of small gaseous ligands (N(2), CO, NH(3), C(2)H(4), H(2), O(2)) at an iridium center.
- Utilized pincer iridium(I) complex single crystals.
- Observed catalytic hydrogenation of ethylene relative to propylene within the crystal.
Main Results:
- A series of SC-SC transformations were achieved, with the single crystal remaining intact.
- Multiple small gaseous ligands were successfully interchanged at the iridium center without prior ligand extrusion.
- Selective hydrogenation of ethylene over propylene (25:1) was observed in pincer iridium single crystals passivated by CO.
Conclusions:
- Demonstrated the feasibility of SC-SC transformations involving gaseous ligand exchange in nonporous molecular crystals.
- Showcased selective catalysis occurring within a single crystal environment.
- Opened new avenues for solid-state reactions and catalysis in molecular crystals.
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