SYNTHESIS, STRUCTURE, AND REACTIVITY OF CHIRAL RHENIUM AMIDO COMPLEXES OF THE FORMULA (ETA-5-C5H5)RE(NO)(PPH3)(NRR')

Reactions of primary and secondary amine complexes [(eta(5)-C5H5)Re(NO)(PPh3)(NHRR')]+ TfO- [2; R/R' = H/H (a), H/CH3 (b), H/C6H5 (d), CH3/CH3 (f), CH2CH2CH2CH2 (h)] with nBuLi give amido complexes (eta(5)-C5H5)Re(NO)(PPh3)(NRR') (1) in quantitative NMR yields. Although 1d can be isolated in pure form, 1f is converted upon workup into a dimeric bridging bis(amido) complex, cis-[(eta(5)-C5H5)Re(NO){mu-N(CH3)2}]2. The crystal structure of 1d exhibits a pyramidal amido nitrogen atom. The diastereotopic methyl groups in 1f readily exchange, as assayed by variable-temperature NMR. Complexes 1a,f react with TfOH to regenerate 2a,f, and with TfOR" to give the corresponding alkylated amine complexes. The basicities and nucleophilicities of the amido nitrogen atoms are shown to be greater than those of organic amines.