Insertions of Isocyanides in Diamidoamine Rhenium(III) Complexes

Rhenium(III) complexes of the form (CO)Re(DAAm) (R) 1, (DAAm = N1-mesityl-N2-(2-(mesitylamino)-ethyl)-N2-methylethane-1,2-diamine) (R = benzyl, 1a; methyl, 1b; 4-OMe-benzyl, 1c) react with isocyanides R′NC, (R′ = 2,6-dimethylphenyl, tert-butyl) to give η1 and η2 iminoacyl complexes. When 2,6-dimethylphenylisocyanide reacts with 1a, the resulting iminoacyl complex was η2 while the reaction with 1c leads to an η1 iminoacyl complex. However, the less bulky isocyanide tert-butyl isocyanide produced only η2 iminoacyl complexes with 1b and 1c. Carbene complexes were obtained by the reaction with methyl triflate. The mechanism for the formation of the iminoacyl complexes in this study was also investigated by DFT (APFD).