Reaction of [TpRh(C2H4)2] with Dimethyl Acetylenedicarboxylate: Identification of Intermediates of the [2+2+2] Alkyne and Alkyne–Ethylene Cyclo(co)trimerizations

Authors:
Publisher website
Google Scholar
Abstract
The reaction between the bis(ethylene) complex [TpRh(C2H4)2], 1, (Tp=hydrotris(pyrazolyl)borate), and dimethyl acetylenedicarboxylate (DMAD) has been studied under different experimental conditions. A mixture of products was formed, in which TpRhI species were prevalent, whereas the presence of trapping agents, like water or acetonitrile, allowed for the stabilization and isolation of octahedral TpRhIII compounds. An excess of DMAD gave rise to a small amount of the [2+2+2] cyclotrimerization product hexamethyl mellitate (6). Although no catalytic application of 1 was achieved, mechanistic insights shed light on the formation of stable rhodium species representing the resting state of the catalytic cycle of rhodium‐mediated [2+2+2] cyclo(co)trimerization reactions. Metallacyclopentene intermediate species, generated from the activation of one alkyne and one ethylene molecule from 1, and metallacyclopentadiene species, formed by oxidative coupling of two alkynes to the rhodium centre, are crucial steps in the pathways leading to the final organometallic and organic products.
Funding Information
  • FEDER
  • Spanish Ministerio de Economia y Competitividad (CSD2007-0006, CTQ2014-51912-REDC)
  • Junta de Andalucía (FQM-119)

This publication has 78 references indexed in Scilit: