Abstract
The electrochemical oxidation of a series of tricarbonyl hormonal steroid complexes, M(CO)3(steroid), (M = Cr, Mo, W; steroid = estrone 3-methyl ether, estrone, estradiol), has been examined in the nonco-ordinating solvent, dichloromethane. Three oxidation processes are observed at fast scan rates.[formula omitted] from a chemically reversible one-electron oxidation process into a chemically irreversible two-electron step.The rate of rearrangement of [M(CO)3(steroid)]+ is markedly dependent on the nature of the steroid. Thestability order for [M(CO)3(steroid)]+ shows a well-defined trend: [Cr(CO)3(steroid)]+ >> [Mo(CO)3(steroid)]+> [W(CO)3(steroid)]+. Controlled potential electrolysis experiments at potentials more positive than eitherprocess 1 or process 2 are consistent with a two-electron transfer. The uncomplexed steroid is recoveredquantitatively in these experiments, without any evidence for rearrangement, and the overall oxidation process on the synthetic time scale is therefore M(CO)3(steroid) →* M(II) + 3CO↑ + steroid + 2e-. Chemical oxidation with NOPF6 is also consistent with an oxidative elimination reaction generating free steroid. The mechanism proposed to account for the data is compared with those previously reported for arene complexes in coordinating solvents.
Original language | English |
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Pages (from-to) | 385-391 |
Number of pages | 7 |
Journal | Organometallics |
Volume | 6 |
Issue number | 2 |
DOIs | |
Publication status | Published - 1 Feb 1987 |
Externally published | Yes |