Atropisomeric properties of 5N-benzoyl-1,5-benzodiazepin-2-one with two Ar−N(CO) axes moving like gears were investigated. The rotationalbarrier (ΔG≠) of the axes was strongly influenced by the electronic effect of the p-substituent on benzoyl, and the electron-withdrawing group (EWG) increased the stability of the axes. The ΔG≠ values were linearly correlated with the electronic effect (the Hammett