The Amide Route in Imine Metathesis with Imidomolybdenum Catalysts: A   Model DFT Study

Abstract

Gradient-corrected density-functional computations (BP86/ECP1 level) confirm the viability of the recently proposed reaction pathway for imine metathesis with imidomolybdenum(VI) species [Mo(NR)₂L_x] (e.g., L_x = Cl₂, DME; R = tBu). In addition to a Chauvin-type [2+2] addition-elimination mechanism, model calculations for the [MoCl₂(NH)₂] + NH₃ + CH₂NH system corroborate the suspected involvement of amido intermediates such as [MoCl₂(NH)(NH₂)₂] and . Several catalytic cycles are characterised that differ in the stereochemistry of the ligands about Mo. The lowest computed rate-determining barriers are only a few kcal mol^-1 higher than that obtained for the Chauvin-type mechanism in the [MoCl₂(NH)₂] + CH₂NH system via , provided the necessary H-atom transfers are catalysed efficiently by traces of base.