Pulse radiolysis of iron pentacarbonyl solutions: the role of the

J . Phys. Chem. 1985,89,4578-4580

4578

Pulse Radiolysis of Iron Pentacarbonyl Solutions: The Role of the Tetracarbonyl Radical Anion Donald T. Reed, Wilma K. Meckstroth, Department of Chemistry, The Ohio State University, Columbus, Ohio 43210

and Douglas P. Ridge* Department of Chemistry, University of Delaware, Newark, Delaware 19716 (Received: September 10, 1984; In Final Form: April 22, 1985)

Pulse radiolysis of dilute THF solutions of Fe(CO)5 produce a species which absorbs at 310 nm. The absorption shifts in ionic solution suggesting that the absorbing is ionic. The rate of disappearance of the absorbing species gives a rate constant of 3.1 X lo8 M-' s-' for its reaction with Fe(CO)5. Comparison with the gas-phase photodissociation spectrum of Fe(CO), and the kinetics of the gas-phase reaction between Fe(C0)4- and Fe(CO), suggests that the absorbing species is Fe(CO),-.

Introduction The intermediacy of 17 electron-transition-metal complexes is important in a variety of synthetic and catalytic processes.' Radical metal carbonyls whose reactivities have been studied include v ( c o ) 6 , zMn(C0)5,3Re(C0)5," Cr(C0)6+,5 Cr(CO)5-,6 C O ( C O ) ~as , ~well as Fe(C0)4-.8 These species tend to be so reactive that they are difficult to observe directly. This in turn complicates the study of their reactivity. It is thus of interest that Fe(CO)< can be observed directly in both gas and condensed phase under circumstances where its reactivity can be examined. Recently a series of radical-metal carbonyl clusters have been reported to be the result of reducing iron pentacarbonyl with Na in tetrahydrofuran at -80 0C.8 The species identified were Fe2(CO)8-, Fe3(C0)"-, Fe3(CO)'1, and Fe4(CO)l