Copper-Catalyzed Phosphinidene Transfer to Ethylene, Acetylene, and Carbon Monoxide: A Computational Study

A DFT study of phosphinidene transfer by copper model catalysts is reported. PR-transfer pathways are highly exergonic with respect to catalyst and phosphinidene transfer reagent. Calculated free energy barriers by which (dhpe)Cu(PMe) active species yields functionalized products are reasonable for modeled substrates ethylene, acetylene, and carbon monoxide. Calculations suggest a (dhpe)Cu-I(-PMe center dot-) formulation as more appropriate than (dhpe)Cu-II(=PMe2-). The preferred pathway for production of phosphirane (phosphirene) is via direct [1 + 2] addition of ethylene (acetylene) to the PMe group of (dhpe)Cu(PMe), which contrasts the [2 + 2] mechanism for the reaction of ethylene with Ni-0-phosphinidenes. In light of simulations for neutral and cationic models, it is concluded that the extra electron in copper destabilizes [2 + 2] pathways. Calculated energetics for (dhpe)Cu(PMe) versus (en)Cu(PMe), dhpe = 1,2-bis(dihydrophosphino)ethane, en = ethylenediamine, indicate that the former is a more potent for PR-transfer. Thus, it is inferred that modifications that result in a more electron deficient metal center will yield better group transfer catalysts. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 110: 1702-1711, 2010