Activation of alkynes by an α-diimine-stabilized Al-Al-bonded compound: insertion into the Al-Al bond or cycloaddition to AlN2C2 rings.

The reaction of dialumane, [L(2-)(THF)Al(II)-Al(II)(THF)L(2-)] (1, L = [(2,6-iPr2C6H3)NC(Me)]2), with the less reactive diphenylacetylene affords a new insertion product [L(2-)(THF)Al(III)(PhC=CPh)(2-)Al(III)(THF)L(2-)] (2). Reaction of 1 with phenylacetylene (or 4-ethynyltoluene), however, proceeds through cycloaddition of alkynes to the AlN2C2 rings to produce bis(bicyclic) products (3a and 3b).