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

The water-soluble iron-carbonyl complex Fe(CO)(3)(TPPTS)(2) (2) (TPPTS = tr iphenylphosphine trisulfonate, sodium salt) was prepared and its molecular structure was determined by X-ray crystallography to be distorted bipyramid al. The oxidation chemistry of 2 to the 17-electron organometallic radical 2(+) was studied. Thus, complex 2 was oxidized chemically with Ce(IV) in H2 O, resulting in rapid disproportion of the intermediate 2(+) to 2 and Fe(II )(aq), with concomitant loss of both the CO and the TPPTS ligands. The oxid ative disproportionation of 2 with AgNO3 proceeded through formation of a l inear [{(TPPTS)(2)(CO)(3)Fe}(2)Ag](+) intermediate. Electrochemically, comp lex 2 was oxidized irreversibly at E-p = 466 mV (vs. Ag / AgCl, 100 mV s(-1 )) in H2O. (C) 2001 Elsevier Science B.V. All rights reserved.