Dehydrogenation of formic acid by Ir-bisMETAMORPhos complexes: experimental and computational insight into the role of a cooperative ligand

被引：72

作者：

Oldenhof, Sander ^{[1
]}

Lutz, Martin ^{[2
]}

de Bruin, Bas ^{[1
]}

van der Vlugt, Jarl Ivar ^{[1
]}

Reek, Joost N. H. ^{[1
]}

机构：

[1] Univ Amsterdam, van t Hoff Inst Mol Sci, NL-1098 XH Amsterdam, Netherlands

[2] Univ Utrecht, Bijvoet Ctr Biomol Res, NL-3584 CH Utrecht, Netherlands

来源：

CHEMICAL SCIENCE | 2015年 / 6卷 / 02期

关键词：

CATALYZED HYDROGENATION; CARBON-DIOXIDE; REGIOSELECTIVE HYDROFORMYLATION; REVERSIBLE HYDROGENATION; SUPRAMOLECULAR CATALYST; WATER; ACTIVATION; IRIDIUM; CO2; MECHANISM;

D O I：

10.1039/c4sc02555e

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

The synthesis and tautomeric nature of three xanthene-based bisMETAMORPhos ligands (La-Lc) is reported. Coordination of these bis(sulfonamidophosphines) to Ir(acac)(cod) initially leads to the formation of Ir-I(L-H) species (1a), which convert via formal oxidative addition of the ligand to Ir-III(L) monohydride complexes 2a-c. The rate for this step strongly depends on the ligand employed. Ir-III complexes 2a-c were applied in the base-free dehydrogenation of formic acid, reaching turnover frequencies of 3090, 877 and 1791 h(-1), respectively. The dual role of the ligand in the mechanism of the dehydrogenation reaction was studied by H-1 and P-31 NMR spectroscopy and DFT calculations. Besides functioning as an internal base, bisMETAMORPhos also assists in the pre-assembly of formic acid within the Ir-coordination sphere and aids in stabilizing the rate-determining transition state through hydrogenbonding.

引用

页码：1027 / 1034

页数：8