Formation of N-Methylated Cyclic Ligand Systems from Unusual Reactions between Trimethylamine <i>N</i>-Oxide and Acetylenes on Fe₃Te₂(CO)₉ and Contrast with Reactions on Fe₃E₂(CO)₉(E = S, Se)

Activation of C−H bonds of N-methyl groups has been achieved on cluster support. Use of a noncoordinating solvent in the reaction of Me3NO·2H2O, acetylenes, and Fe3Te2(CO)9 leads to activation of N-methyl groups of Me3NO and formation of N,N-dimethyldihydropyrrole (1) and N,N′-dimethylhexahydropyrimidine (2) ring systems. The NMe3 ligand, resulting from TMNO, is retained on the metal cluster due to the absence of a coordinating solvent and reacts with incoming acetylenes. In contrast, activation of the N-methyl groups of Me3NO is not observed in the reaction using Fe3S2(CO)9, which yields complexes with vinylferrocene (3) and 1,4-diferrocenylbuta-1,3-diene-2,3-dithio (4) units attached to Fe2S2(CO)6. All new compounds have been structurally characterized by single-crystal X-ray diffraction studies.