10.1021/om101114c.s001 Samuel S. Karpiniec Samuel S. Karpiniec David S. McGuinness David S. McGuinness Michael G. Gardiner Michael G. Gardiner Brian F. Yates Brian F. Yates Jim Patel Jim Patel Revisiting the Aufbau Reaction with Acetylene: Further Insights from Experiment and Theory American Chemical Society 2011 2C binding mode increases chain growth Aufbau reaction acetylene chain growth insertion proceeds dimer formation chain termination Al Aufbau Reaction 2011-03-28 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Revisiting_the_Aufbau_Reaction_with_Acetylene_Further_Insights_from_Experiment_and_Theory/2676919 The first steps of acetylene chain growth at AlEt<sub>3</sub>, via migratory insertion, have been investigated both experimentally and theoretically. The first insertion into the Al−Et bond occurs readily, leading to the stable alkenyl-bridged dimer [{Et<sub>2</sub>Al(μ-CHCHEt)}<sub>2</sub>] (<b>1</b>). The alkenyl bridging mode has been observed through isolation and structural analysis of Al<sub>2</sub>Et<sub>2</sub>(OC<sub>6</sub>H<sub>3</sub>Ph<sub>2</sub>)<sub>2</sub>(μ-CHCHEt)(μ-OC<sub>6</sub>H<sub>3</sub>Ph<sub>2</sub>) (<b>2</b>), synthesized by way of controlled reaction of <b>1</b> with 2,6-Ph<sub>2</sub>C<sub>6</sub>H<sub>3</sub>OH. This stable binding mode increases the barrier to a second insertion of acetylene, as insertion proceeds through monomeric Al-acetylene adducts. The energetics of further chain growth, dimer formation, and chain termination via hydrogenolysis were investigated theoretically. The results provide further insight and explanation for previous experimental findings in relation to the Aufbau reaction with acetylene.