Stable Salts of Heteroleptic Iron Carbonyl/Nitrosyl Cations.

The oxidation of Fe(CO)5 with the [NO]+ salt of the weakly coordinating perfluoroalkoxyaluminate anion [F-{Al(ORF )3 }2 ]- (RF =C(CF3 )3 ) leads to stable salts of the 18 valence electron (VE) species [Fe(CO)4 (NO)]+ and [Fe(CO)(NO)3 ]+ with the Enemark-Feltham numbers of {FeNO}8 and {FeNO}10 . This finally concludes the triad of heteroleptic iron carbonyl/nitrosyl complexes, since the first discovery of the anionic ([Fe(CO)3 (NO)]- ) and neutral ([Fe(CO)2 (NO)2 ]) species over 80 years ago. Both complexes were fully characterized (IR, Raman, NMR, UV/Vis, scXRD, pXRD) and are stable at room temperature under inert conditions over months and may serve as useful starting materials for further investigations.