Generation of 17-electron organometallic radicals in aqueous solution; chemical and electrochemical oxidation of Fe(CO) 3(TPPTS) 2

Abstract

The water-soluble iron–carbonyl complex Fe(CO) 3(TPPTS) 2 ( 2) (TPPTS=triphenylphosphine trisulfonate, sodium salt) was prepared and its molecular structure was determined by X-ray crystallography to be distorted bipyramidal. The oxidation chemistry of 2 to the 17-electron organometallic radical 2 + was studied. Thus, complex 2 was oxidized chemically with Ce(IV) in H 2O, resulting in rapid disproportionation of the intermediate 2 + to 2 and Fe(II) aq, with concomitant loss of both the CO and the TPPTS ligands. The oxidative disproportionation of 2 with AgNO 3 proceeded through formation of a linear [{(TPPTS) 2(CO) 3Fe} 2Ag] + intermediate. Electrochemically, complex 2 was oxidized irreversibly at E p=466 mV (vs. Ag ∣ AgCl, 100 mV s −1) in H 2O.