A Rearrangement of Azobenzene upon Interaction with an Aluminum( I ) Monomer LAl {L = HC[(CMe)(NAr)] 2 , Ar = 2,6‐ i Pr 2 C 6 H 3 }

Reaction of LAl ( 1 ) or [LAl{η 2 ‐C 2 (SiMe 3 ) 2 }] ( 2 ) {L = HC[(CMe)(NAr)] 2 , Ar = 2,6‐ i Pr 2 C 6 H 3 } with azobenzene affords a five‐membered ring compound [LAl{N(H)‐ o ‐C 6 H 4 N(Ph)}] ( 3 ). In the formation of 3 a three‐membered intermediate [LAl(η 2 ‐N 2 Ph 2 )] ( A ) is suggested by a [1 + 2] cycloaddition reaction; A is not stable and further rearranges to 3 . DFT calculations on similar compounds with modified L' {L' = HC[(CMe)(NPh)] 2 } show that the complexation energy of the reaction of L'Al with azobenzene to form [L'Al(η 2 ‐N 2 Ph 2 )] is about–39 kcal mol –1 , and the best estimate of the energy difference between [L'Al(η 2 ‐N 2 Ph 2 )] and [L'Al{N(H)‐ o ‐C 6 H 4 N(Ph)}] is–76 kcal mol –1 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)