HIGH OXIDATION-STATE RHENIUM CP-STAR COMPLEXES CONTAINING HYDRAZINE, HYDRAZIDO, AMMONIA, AND AMIDO LIGANDS

Paramagnetic ReCp*Me4 reacts with triflic acid to give ReCp*Me3(OTf) (1) in 90% yield. Hydrazine reacts with 1 to give diamagnetic [ReCp*Me3(NH2NH2)]+OTf- (2), which is deprotonated to give ReCp*Me3(NHNH2) (3) in good yield. 1 also reacts with ammonia to give [ReCp*Me3(NH3)2]+OTf- (4), which is deprotonated to give ammonia and ReCp*Me3(NH2) (5). Addition of triflic acid to 5 yields [ReCp*Me3(NH3)]+OTf- (6). Reduction of 2 in the presence of 2,6-lutidine hydrochloride in THF yields 1.20 equiv of ammonia, using zinc amalgam, and 1.46 equiv of ammonia, using 0.5% sodium amalgam. In the absence of protons, reduction of 2 by zinc amalgam gives 1.00 equiv of ammonia.