A Series of Pincer-Ligated Rhodium Complexes as Catalysts for the Dimerization of Terminal Alkynes

作者：Pell Christopher J; Ozerov Oleg V^*

来源：ACS Catalysis, 2014, 4(10): 3470-3480.

DOI：10.1021/cs5009317

• pincer
• alkyne dimerization
• rhodium
• catalysis
• phosphine
• enyne

A series of pincer complexes of Rh has been prepared and tested as catalysts for the dimerization of terminal alkynes. The pincers included aryl/bis(phosphinite) POCOP, aryl/bis(phosphine) PCP, and diarylamido/bis-(phosphine) PNP ligands. Rh-I complexes of the general form (pincer)Rh((SPr2)-Pr-i) or (pincer)Th(H-2) were used as catalysts. In addition, the apparent donating ability of the pincer ligands was gauged through the carbonyl stretching frequencies in (pincer)Rh(CO) complexes by IR spectroscopy. All surveyed Rh complexes acted as catalysts for dimerization of 4-ethynyholuene, 1-hexyne, or trimethysilylacetylene. The products were a mixture of E- and gem-enyne isomers, with small amounts of oligomers in some cases. The Z-enyne isomers were not observed except in two reactions. None of the catalysts showed useful selectivity for either the E- or the gem-enyne product. However, the POCOP-based catalysts bearing (PPr2)-Pr-i donor arms performed faster and possessed apparently greater longevity (up to 20 000 TON) than the previously reported pincer Rh catalysts.

• 出版日期2014-10