Electrochemical Behaviour of the Fe(CO)₃NO^⊖ Ion

Abstract

The Polarographie behaviour of [ (C2H5)4N] ® [Fe(CO)3NO] e has been investigated at the mercury dropping electrode and platinum stationary electrode.It was found that the complex displays two anodic and one cathodic waves. On the basis of the results obtained a mechanism is proposed and discussed.Polarographic studies have been carried out recently on several carbonyl 1 and carhonyl-nitrosyl 2 complexes with the aim of obtaining information on the electronic structure of the M -CO and M -NO bonds.In the reduction of carbonyl complexes the electronic change is localized on a prevailing central metal orbital. In the nitrosyl complexes, however, it is the JTNO 2 orbital which is involved in the reduction process, apart from some cases in which the presence of cr-allylic ligands completely modifies the reduction mechanism giving rise to the cleavage of the M-allyl 'bond 3 . This paper reports results on the Fe(CO)3NO e ion, with the aim of comparing its polarographic behaviour with that of the isoelectronic Co(CO)4 e ion 4 and to find out if in this ionic nitrosyl carbonyl complex it is still the orbital which is involved in reduction. Experimental[Et4N][Fe(CO)3NO] and Hg[Fe(CO)3NO]2 were prepared and purified as in the literature 5 . Since compounds were very sensitive to oxygen, they were handled in an argon atmosphere.Electrochemical measurements were carried out in acetonitrile, purified as in 1. c. 6 . Other experimental details have been reported previously 3 . Results and DiscussionThe complex [Et4N] ® [Fe(CO) 3NO] e shows two anodic waves and one cathodic wave at the dropping mercury electrode (Fig. 1).The two anodic waves, at -0.067 and + 0.63 V (for a depolarizer concentration of 2-10 _3 m) have Request for reprints should be sent to Dr. S. M. MURGIA,

The Reincarnation of the Hieber Anion [Fe(CO)3(NO)]– – a New Venue in Nucleophilic Metal Catalysis

“…Similar detailed structural analyses for complexes of the general type M[Fe(CO) 3 (NO)] have been carried out 27. IR spectroscopic investigations indicated a similar solvent‐dependent behaviour of these complexes as described above for the carbonylferrate 5 28.…”