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Coordination versatility of p-hydroquinone-functionalized dibenzobarrelene-based PC(sp3)P pincer ligandsElectronic supplementary information (ESI) available: Full spectroscopic data and experimental details have been deposited. CCDC 1411539, 1411549, 1411551-1411553 and 1495177. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6dt02201d
The manuscript describes the synthesis and coordination chemistry of a novel diphosphine pincer ligand based on a p -hydroquinone-functionalized dibenzobarrelene scaffold. The p -hydroquinone fragment of the ligand is oxidatively and coordinatively non-innocent and may render new reactivity to the m...
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Main Authors: | , , , , , |
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Format: | Article |
Language: | English |
Online Access: | Get full text |
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Summary: | The manuscript describes the synthesis and coordination chemistry of a novel diphosphine pincer ligand based on a
p
-hydroquinone-functionalized dibenzobarrelene scaffold. The
p
-hydroquinone fragment of the ligand is oxidatively and coordinatively non-innocent and may render new reactivity to the metal center due to implied reversible redox behavior, tautomeric interconversion and metal-hydroxyl/alkoxide coordination switch of the pendant hydroxyl side-arm. Palladium, platinum and iridium complexes were prepared and characterized. Investigation of their coordination chemistry revealed that while tautomeric equilibrium exists in free ligands and in the chelate non-metalated complexes, it is essentially blocked in the corresponding C(sp
3
)-pincer compounds due to stabilizing hemilabile coordination of the hydroxyl group. However, its presence in close proximity to the metal center is essential for catalyzing acceptorless dehydrogenation of alcohols by the iridium complexes
via
the outer-sphere hydrogen transfer mechanism. Remarkably, we found a similar activity for the analogous palladium complexes, which is not characteristic of this metal. This unprecedented reactivity of palladium stresses the fact that besides the choice of an active metal, transformation-oriented design of the ligand is crucial for catalysis.
Bifunctional hydroquinone-based PC(sp
3
)P pincer complexes. |
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ISSN: | 1477-9226 1477-9234 |
DOI: | 10.1039/c6dt02201d |