The pyrrolyl-N complex (eta5-C5H5)Re(NO)-(PPh3)(NC4H4) and TfOH or HBF4.OEt2 react to give 2H-pyrrole complexes [(eta5-C5H5)Re(NO)(PPh3)-(N=CHCH=CHCH2)]+X-. These rearrange to the carbon-ligated species [(eta5-C5H5)Re(NO)(PPh3)-(C=NHCH2CH=CH)]+X-, which is characterized crystallographically and treated with KH to give the pyrrolyl-C complex (eta5-C5H5)Re(NO)(PPh3)(C=CH-CH=CHNH).