Reduction of carbodiimides by a dialumane through insertion and cycloaddition

The dialumane [(L2-AlII)-(AlL2-)-L-II] (L = [(2,6-iPr(2)C(6)H(3))NC(Me)](2); 1) reacts with carbodiimides, RN & xe001;C & xe001;NR (R = Cy, iPr), through insertion, [2+4] cycloaddition, and a hydrogen transfer process. However, with the bulkier carbodiimides (R = dipp = 2,6-iPr(2)C(6)H(3),tBu), the reactions are sterically controlled and lead to the formamidinate products.