X-ray structure and dynamic behaviour in solution of N-methylthio-N'- -(2,6-dimethylphenyl)-2,6-dimethyl-1,4-quinonediimine formed by the alcoholysis of [Me2Al{2,6-Me2C6H3NS(Me) NC6H3Me2-2,6}]2

Abstract

Reaction of [Me{2}Al{RNS(Me)NR}]{2} (R = 2, 6-Me{2}C{6}H{3}) with t-BuOH affords N-methylthio-N-(2,6-dimethylphenyl)-2,6-dimethyl-1,4-quinonediimine in 67% yield. The X-ray structure of this compound shows that two conformational isomers are present in the solid. Temperature dependent }1{}3{C and }1{H NMR measurements show that in solution these conformers exchange at a rate which is fast on the NMR time scale at + 60}o{C and slow at -{6}{0}}o{C. From the coalescence point of two of the }1{}3{C resonances, the free energy of activation is estimated to be 13.7 + 1.0 kcalmol at 10}o{C. Possible processes for the exchange are discussed, and also a reaction scheme for the formation of the title compound is discussed.