Diazabutadienes as ligands.I. Compounds of aluminium: coordination of diazabutadienes to Al(CH3)3 and subsequent intramolecular insertion and rearrangement reactions leading to [(CH3)2Al(RNCH(CH3)C(R')=NR)] (R' = H, CH3) and (CH3)2AlRNCH2C(CH3) =NR

Abstract

Reaction of R-N=CH-CH=N-R with [(CH{3}){3}Al]{2} affords the coordination product (CH{3}){3}AlRN=CH-CH=NR (A) for R = 2, 6-(CH{3}){2}C{6}H{3} and 2,4,6(CH{3}){3}C{6}H{2}. For R = 4 ClC{6}H{4}, 4-CH{3}C{6}H{4} and 4-CH{3}OC{6}H{4}, insertion takes place, giving the complexes (CH{3}){2}AlRN-CH(CH{3})-CH=N-R (B), in which Al is part of a five-membered chelate ring. Depending on the temperature both the addition and insertion products rearrange intramolecularly to the complexes (CH{3}){2}-AlR-N-CH{2}-C(CH{3})=N-R (C), in which Al is also part of a five-membered chelate ring. Reactions of the asymmetric (CH{3}){2}HC-N=CH-C(CH{3})=N-CH-(CH{3}){2} with [Al(CH{3}){3}]{2} also leads to an insertion product, (CH{3}){2}AlRN--CH(CH{3})-C(CH{3})=N-R (B') (R = (CH{3}){2}CH), but there is no subsequent rearrangement in this case.A mechanism involving hydrogen migration is tentatively proposed to account for the observed isomerization, which increases in rate in the order:R = (CH{3}){3}C>2,4,6-(CH{3}){3}C{6}H{2}> 2,6-(CH{3})2C{6}H{3} (A -> C)andR = 4-CH{3}OC{6}H{4}>4-CH{3}C{6}H{4}>4-ClC{6}H{4} (B -> C)Hydrolysis of isomer C gives the unknown imino amines R-NH-CH{2}-C(CH{3})=N-R in quantitative yield.