Generation of 17-electron organometallic radicals in aqueous solution; chemical and electrochemical oxidation of Fe(CO)_3(TPPTS)_2

摘要

The water-soluble iron-carobnyl 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 oranometallic radical 2~+ was studied. Thus, complex 2 was oxidized chemically with Ce(IV) in H_2O, resulting in rapid disproportionation of the intermedaite 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 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.